Mosquitofish Stats
Minimum Tank Size: 10 Gallons
Care Level: Easy
Water Conditions: 6.0-8.0 and Medium to Hard
Temperature: 10-29 °C (50-84 °F)
Maximum Size: 2 inches (5 cm)
The mosquitofish (Gambusia affinis) is small live-bearer fish that is only rarely seen in the aquarium hobby. There are actually two species of mosquitofish, with the western mosquitofish more commonly available for sale, and the eastern mosquitofish (G. Holbooki) almost never being found in fish stores.
The mosquitofish is one of the few commercially available fish that are native to North America and they were originally found in the Mississippi River and in the streams and rivers of Illinois and Indiana. They have now spread throughout the globe, largely due to their near legendary hardiness. They are now considered a major invasive threat in several countries, and have severely impacted the ecosystems of Australia.
The mosquitofish remains small in the home aquarium, with the females reaching about 3 inches in length and the male 1.5 inches. The males and females are easy to differentiate, with the males developing a bright red tail upon sexual maturity and the females developing a gravid spot (a dark spot near the rear of their abdomen.)
Housing
The mosquitofish is incredibly easy to care for, and can survive extremes in temperature and salinity. It will also thrive in low oxygen environments with poor water quality, making this fish difficult to kill even by novice fish keepers.
While most mosquitofish are kept in ponds to control – you guessed it, mosquitos, they will also do well in small aquariums. They can be housed quite easily in a 10 gallon aquarium and will thrive if you provide them with anything larger.
Something important to remember, is that mosquitofish are known as fin nippers and can be aggressive at times. While most small minnows will be perfectly compatible with mosquitofish, you should stay away from any long finned fish, or any slow moving, docile fish like fancy goldfish.
When choosing a filter, you should remember that these are live bearing fish, and a hang-on-back filter is a death sentence to any fry if you don’t cover the intake. The best choice for any liver-bearer tank is a sponge filter, but a hang-on-back filter does provide better filtration if you are able to remove the fry from the tank, or as previously stated, cover the filter intake to prevent the fry being sucked up to rather unpleasant deaths.
I would strongly recommend choosing an Aquaclear Power Filter
Feeding
In the wild, mosquitofish primarily eat small insects, larvae and small amounts of plant material and algae. They will also consume massive amounts of mosquito larvae, and the females have been known to consume more than their body weight in a single day.
In the home aquarium they should be fed a high quality flake food, along with live or frozen foods. I personally use Hikari Micro Wafers
Their preferred live food is obviously mosquito larvae, but that can be hard to come by and there can be certain legal ramifications relating to breeding mosquitos. Most areas prohibit the breeding of mosquitos, and you should check with your local authorities before attempting to breed them. If you are able to breed mosquito larvae, then be sure to harvest it completely so that no larvae are able to mature into adult mosquitos.
Breeding
Mosquitofish are actually one of the more difficult to breed live-bearer fish. Once you have sexed the fish, it’s always best to have a ratio of about one male for every three females. This ensures that the males won’t harass one female all the time, which can result in illness or even death from the stress.
The problem with the breeding of mosquitofish arises after the female has been impregnated. They are able to delay delivering the fry if there are threats nearby, and they consider male mosquito fish to be threats. If you want the female to deliver her fry, then you either need to relocate her to another tank once she’s showing as pregnant, or place her in a breeder box in the tank, so that she’s separated from the males.
Once she has been separated, she will normally give birth to numerous fry in a short period of time. To prevent any unpleasant cannibalism, the mother should be removed as soon as possible, though most females tend to ignore their young.
The newborn fry can be feed baby brine shrimp, mircoworms or finely ground up flake food. They can also be fed any of the now numerous fry foods commercially available.
Hi there. I’m wondering at what age can you put fry back into the community tank. Can’t find the answer anywhere.
Thanks!
It’s not scientific but I always make sure that the babies are larger than the mouths of the largest fish I’m the aquarium. If you feel uncomfortable with that, then you can make sure that they’re at least the width of a dime. That way they’re large enough to compete for food and won’t be eaten.
I would never go with the age of the fish, since their growth can be vastly different bases on food, temperature and available space.
that’s what i’ve been hearing, robert. thanks for the help. i really can’t tell if they are big enough to fit in the adult fishes’ mouths. there are just two adult female and one adult male mosquito fish in the tank. the fry are about a centimeter long and about 2-3 weeks old. i did put two in a breeder box in the tank and the females were very aggressive toward them.
That’s strange that the females were aggressive. I find that it’s mostly my males mosquitofish that are the aggressive fish. And about a centimeter long is usually good enough. Is the tank planted? If it is, that will help the juvenile fish to avoid any aggressive adults easily.
I have two pregnant females in a tank with one other male mosquito fish, 3 male guppies, and one male beta. Can I move them to a 2 Gallon holding tank to give birth? I have not been using the tank and it is not cycled. I have had other fish in there at times and they did fine. Will the females eat their fry, and how many do you think there will b?
I wouldn’t move them into an unfiltered tank when they’re pregnant. Things could go very bad for the pregnant females in an uncycled tank, and the babies would never survive in there. If anything, I would use a tank divider instead, if you have access to one.
The school gave my son a fish. brought it home put in the bowl,with in 15min the fish dies.what happend?
It was probably shock from not being acclimatized to the new conditions. They need to be slowly introduced the new water type – especially if there are great differences in pH and temperature. The easiest way to do this is the float method. Place them in a leak proof plastic bag floating in their new aquarium. Let the temperature equalize for about 15 minutes, and then open the bag to add a cup of aquarium water to it. Repeat this every 5-10 minutes until the bag is full. Discard half the bag, and the refill it continuing about a cup every 5-10 minutes. Once it is full again, they should be used to the water. Net the fish out (being careful not to add any of the water in the bag), and place them carefully in the aquarium. That should prevent the death you experienced in the future.
Bet they used Tap Water, will kill any fish, you have to de-chlorinate
My thought exactly..lol. especially if they died that fast..
I was wondering my fish are upside down I don’t know if there sleeping or if there dead
Are they moving at all? If they’re not moving their gills at least, they’re most likely dead. If they’re still moving, it could illness or a swimbladder problem. Do they appear bloated?
My fish have been living in storage tubs with tap/well water for a while so it really depends on how hard the water is cuz they legit get hose water
does the tank have to be 10 gallons
You might be able to get away with a 5 gallon, but I wouldn’t try it. Mosquitofish tend to be aggressive, and you would probably have some pretty serious aggression issues with anything smaller than a 10 gallon tank. Also since they tend to produce a fair amount of waste, so it would be a struggle to keep the water quality up in a 5 gallon tank – even if you kept their numbers down to a handful.
I caught one of these fish as a very small baby and I’ve been caring for it by giving it egg yolk.
I’m happy to say she’s grown up enough for me to identify her as a female mosquito fish (at least I’m fairly sure that’s what she is)
She now eats tropical flake food comfortably and lives in a 1 gallon fish bowl from the dollar store and she’s over a cm in length
But I’m worried about how much space she’ll need and I’m not sure how sensitive she’ll be to water temperature
I’m also worried that not having other fish might affect her health/happiness since we originally had two but the other one wasn’t eating the yolk like she did.
Your fish would be quite happy in 5 gallon aquarium, unless you want to add a few more fish to the tank, then I’d go for a 10 gallon aquarium at the minimum. As for the temperature, mosquitofish are adaptable to a wide range of temperatures and don’t require a heater (unless the room gets very cold in winter).
Hopefully your fish will enjoy the new aquarium you get for her.
I’m not a breeder, but my mosquito fish had babies.How can I make sure my female fish are done having babies?
Also, does there have to be pebbles in the tank?
When a live bearer gives birth, it will always give birth to all of its babies. Of course most of them will immediately become pregnant again, so you can expect this to repeat itself every few months.
As for pebbles, I would recommend having substrate in your tank, though sand or gravel would work just find. However, you should include hiding places for the fry, or they will be eaten by the parents. Good hiding places are dense plants like Java moss, or floating plants that allow them to hide in the roots.
Ok. Thanks. Also, do they have to be around males for each batch of babies? I have 2 female fish and no male fish. I got them for free and they became pregnant before I got them. Will they keep having babies?
The females can store sperm for several months, so they will most likely continue to have batches of fry long after they have been removed from the company of any males.
Ok. Looks like I’m going to have a lot of fish!
Do you know of any places I can give my mosquitofish?
A lot of fish stores will take them off you hands, but they’ll probably end up as feeder fish. I’ve also known garden centers to take them sometimes, since they are popular in ponds – at least in my area (northern Canada). If that fails, you can always try local fish forums, or even Craiglist or its equivalent in your area. People always want free fish.
I would love some mosquito fish
You can usually find them very cheap at garden centers at this time of year. A lot of people buy them to put them in their ponds. Otherwise, they can be pretty hard to find, but definitely worth it if you can find them.
After reading every word of this entire thread, (the most informative and helpful text I found anywhere) I bought a few mosquito fish and a couple of goldfish! Unfortunately, the customer service rep where I purchased them told me that I could not be selective regarding the sex of the fish, or how many of each sex were purchased. Basically, “You get what you get.” 1 of them is obviously a pregnant female. She is in her own tank, separate from the males and away from predators, with plenty of hiding places for herself and her young. I’m eagerly anticipating the arrival of her fry. Sorry, I’m rambling. What I wanted to tell you, or ask you, rather is this… Since I moved her into the tank she seems to have lost her pigment. She’s white now. Is this something I should be alarmed about!? I’ve been unable to find any information regarding a change in pigment anywhere, so I’m concerned. Any info you may have would be appreciated.
A fish turning white is often a sign of stress. While she may be stressed from her new environment, a fish turning white is usually a sign that something is off with the water. Was the aquarium cycled before you put her in the tank? I’d get the water tested as soon as you can and try to do a few small water changes (10-15%) of the water. Also, make sure not to overfeed, as the water may be slightly off already. If your water is fine, then it may be a bacterial infection, but I’d proceed on the assumption that it’s a water problem personally.
If you have a mosquito and vector control county organization in your county you can often get them free. We had large pools of water we didn’t want to empty due to having fish in them. They gave us about a hundred of them for free to help control the mosquitos…
I got free mosquito fish from our county and district distribution day. They do in the Summer, started with about 15 fish, a couple were dead when my husband opened the container with a lid ( I assume lack of oxygen) ? Anyways got them in a non working 3 Level garden fountain and put about 13 in the fountain. Next day another died but for the most part I think we have survivors and hide very well in debri and in fountain crevice, We already see a fry and I took about four of the fry and separate but more are to come because I see about five pregnant females. If I feed them will they leave the fry alone. We’ve had them for 3 weeks now. One just died this week by turning white, started at the tail, bright white and scales fraying. Eventually died but was like that for a week. Are fish infection contagious to other fish?
Fish infections are often contagious and I would recommend doing small water changes over the next few days to try to clean up the water. If it starts to spread, you can pick up medicine at most fish stores.
As for the fry, well-fed parents do sometimes ignore the fry, but the surest way to keep the fry alive is to add live plants – especially floating plants. The fry will hide from the parents and should reach adulthood.
I am an owner of 4 mosquito fish. 1 was already a pet, the others were from the lake. This was very helpful, thank you.
I’m glad I could help. This is a really underrated fish, and it makes a great pet.
My mosquito fish just gave birth and some of the fry look very pale and still have yolks sacs and dont seem to be moving will they live
It sounds like they were dropped early, in an underdeveloped condition. In those circumstances, only a few will generally survive. Hopefully at least some of them are doing well.
I have a male who’s been alive for 4 years now. He lives in a large glass bowl that is filtered and water changed with hard water every two weeks. He started with 6 friends and they all jumped out of the fountain so he’s been solo. I got him one new friend so he wouldn’t be alone. She delivered fry and died. I don’t want to do that again so he will continue to live a solitary life. I enjoy him and feed him flakes morning and night. Thanks for your info, it’s the most complete online. The grandkids named him Skeeter. I am proud of how well I have taken care of the little guy, just hope the aggressive guy isn’t lonely. The other fish he ate their fins.
i want to start a farm for the fish LOL but i will only have like a few will they still need a big tank because in my science class we got 2 fish in like a half gallon tank and i got a water snail and also my fish breeded in 1 week so they r not 2 hard to breed but this web is very helpful 😀 thx
These are a really great fish, and if I had the money I’d probably start a farm too. lol
You mentioned that the pregnant fish can delay birthing the babies if she feels threatened. I have a female that I thought was pregnant because of her enormously distended abdomen, but after placing her in a breeder box for a month she never had babies. Do you have any idea how long delivery can be delayed? Maybe my fish isn’t actually pregnant, just really fat? Any info would be appreciated. I’ve looked all over but can’t find much about mosquito fish…
Does the female had a gravid spot? It’s a very dark spot near the anal fin, which is caused by the scales thinning, and all of the babies eyes becoming visible through the scales. If there is no gravid spot, it’s possible that your fish has bloat. Do you have any pictures?
As for how long they can delay, I’ve never come across a hard number. In everything study or article I’ve read, they state they can delay giving birth for weeks, though no one has ever put an outer limit on how long they can go. I know some of mine have gone at least a month without giving birth while being heavily pregnant.And I’ve found breeder boxes won’t give them the privacy they need. If you want babies quickly, your best best is to set up a separate 5 or 10 gallon tank, where the female can be alone.
Do u know if mosquitofish eat duckweed if so Where do u find duckweed please reply
Sorry for the delay in getting back to you, but I haven’t been able to tend to my website for a while now. But most pets stores carry it, and it’s so invasive I’ve known many to give it away for free. And mosquitofish will eat it, but I’ve only seen them do that when they’re very hungry. They greatly prefer insects and prepared foods.
My mosquito fish eat duckweed and they love it
So do mine!! They also like elodea.
Can you put more then one pregnant mosquito fish together to give birth?
Yes, in the wild the females will often live together and they should give birth in close proximity to others. However, it’s important to provide a secluded location in the tank where the female can go when the time comes.
I just received a mosquito fish as a gift. She’s very tiny. For this tiny fish, do I really need a 10 gallon tank?
You could probably get away with a five gallon tank, but the difficulty with anything smaller is that the water becomes very unstable. It’s very easy to make a mistake with the water and accidentally kill your fish. The larger the tank, the more stable the water conditions, and the healthier most fish will be. When the tank is small, the pH can swing wildly, and any delay in water changes can cause ammonia and nitrites spikes.
I love my mosquito fish. There easy to care for. But mine constantly breed. My oldest female (2 years old) has never delayed birth, And she has never been in a box. I also have three plants in there tank. Along with a fake enemy. They usually survive. (I again, Never use the box. So they swim whenever and wherever). Some of my fry become mishapped, There’s sometimes ben in half. Other times they have cut up fins from being attacked. I can usually help find, But other I just let swim and eventually flush them.
That’s one of the few downsides of the mosquitofish – they can be extremely aggressive at times.
Being bent is usually caused by one of two things. Either it is scoliosis caused by a lack of Vitamin C in their diet at an early age, or the worst case scenario is that they have fish tuberculosis which in freshwater fish, such as mosquitofish, is caused a bacteria called Mycobacterium fortuitum. There is no cure for fish tuberculosis and there is no evidence that it can be transferred to humans. But since they are fry its probably just scoliosis.
How long do they live? I’ve had mine for about 2 years now, I keep her in a 1.2 gallon tank, and I have a BUNCH of babie snails and I’m sure that she has eaten them, because there used to be 30 of them, now there is one, so I’m wondering how long he will be with us(I found her in the wild)
Most females only live for about 1.5-2 years, and the males usually live less than that. If you take extraordinary care of them, I’ve seen them live for up to three years, but that’s pretty well the maximum.
I have a male that is over 3 years 2 months old now. He has a hunch back now ( bump on back)and his organs appear to be enlarged. Basically he looks much different now then he did a year ago .. he still attacks and chases the minnows in his tank. They die from stress and i have to go replace them because he will become bored and appear depressed if he does not have a minnow to harrass. . Sounds silly but im going to be so sad when he passes. So much personality for such a small guy.
It’s always sad when a favorite fish starts to get older. But a bit of a hunched back is normal in an aging fish. But just watch out for lesions on the fish, as a humped back may mean something else then.
i got 4 fish from my canal and put them in my pond and now i have around 40. i put some on a small fish tank 6 males and 1 female i cant scoop them out so i’m just going to let them figure it out c:
That poor female. lol. Hopefully she does alright with that many females, but your pond definitely sounds interesting. Not enough people give mosquitofish a shot in ponds.
How long after the black spots show up on the mosquito fish is pouch can you tell me how long it takes before they give
It should be around 16-28 days after mating, but they have the ability to delay giving birth if they feel it’s not safe for their fry. So in some cases, it may take longer than 28 days.
I’m thinking about getting these to control mosquitos around our yard. What kind of outdoor thing can you suggest? I guess a birdbath is too small? Or just a 10 gallon bucket? Do I need to feed them? thanks!
Unfortunately, they only eat mosquito larvae, and not adult, flying mosquitos. So they’re only handy in controlling mosquitos if you already have a standing body of water where they’re breeding.
But you would need something relatively large, and if you tried to go with something as small as a 10 gallon bucket, you’d need to do regular water changes and have a filter for it. I have heard of some people having success with a rain barrel, but those are usually around 190 litres (50 gallons). Also, they still may need regular water changes, and should be in a somewhat shaded location.
I hope this helps.
My female mosquito fish will eat any mosquitoes that land on the water
Do you keep them outside in a pond or a barrel? And I really enjoy watching fish do stuff like that. There’s nothing more peaceful than watching your fish in a natural setting.
Hi I have 3 pregnant females that are all three very pregnant I removed all three of them from my larger tank and put them in a small 5-gallon take to give birth is it okay to put all three females in the same 5 gallon tank for birthing
It should be fine as long as the tank is cycled. If it’s not cycled, you’ll probably have a huge ammonia surge, which could injure, or kill them all. Especially in a tank that small.
I do have 2 small sponge filters and an underground filter as I grow and clone plants for my 60 gallon tank because I have an electric blue crawdad who loves to eat them also have lots of Life plant in the 5 gallon.. I got the mosquitofish my brother brought them to me as feeder fish but they were way too big at that point for my fish to eat and have been doing very well and keeping the nat and nat eggs away from my tank as we live in California and I have a huge problem with nat and laying their eggs in my big 60 gallon tank with my Jack Dempsey’s and blue and yellow gouramis I have five females and two males mosquitofish and after reading your page and figuring out that how they breed and noticing I had three very pregnant females I decided to remove them so I can grow my own feeder fish to the perfect size unfortunately yes most of the fry will be used as feeder fish but like I said I would love to let some of them mature too to keep them nats and their eggs away so I guess I should have rephrase my question a little bit more are the Fry safe in the tank with all three females until all three give birth I will remove females as I noticed then giving birth or fry or they’re not having black spots or big bellies anymore
My son got two from school. I’ve finally moved the poor things to a tank and it looks like one has ick. I’m totally guessing from when I was younger, but do you know if they are susceptible to it and if so would standard ick medicine be ok for them? (It has white spots on it’s rear fin.)
On a side note, they came with snails and one has survived. Can I move it to the regular tank? The tank has a regular filter and I was concerned the snail might end up in it.
Thanks for the site! It took me a minute to even find info on the fish because I know them better as irrigation fish. Apparently they’re better known as mosquitofish lol
I just recently did an article on ick, so you can find all of the information here. http://aquariumtidings.com/freshwater-ich-treatment-fish/ But if you have any questions about the specific treatment you choose, please let me know.
As for the snail, it will be fine. Most snails seem capable of avoiding filters, and even if they do wander into there, they often survive (depending on the species).
Let me know how it goes for you.
Maybe be careful with the medication and the snail. Some medications are harmful to invertebrates.
Excellent point. I totally forgot about that. Thanks for mentioning it.
i have a minnow fish that is pregnant and is a male/female. is it possible?
What makes you think it’s hermaphrodite? As far as I know, most hermaphrodites don’t have functioning reproductive organs. Though I haven’t heard of that happening with livebearers.
Im doing some research and was looking into getting an ecosystem started in my backyard, I have a 1/4 acre property and we have a 24 ft round pool that we did use for swimming but there is a few tiny holes in the bottom now, My husband and i are were thinking of putting the mosquito fish in the pool, and getting american lotus plants to use as a food source for us, and also use for the mosquito fish to use. Do you recommend anything or think that this is a bad idea? We are not experienced in fish keeping or lotus plant growing. We were thinking that it would be smart to get the plant to grow as a food source for our family and use our pool to do this, the lotus grows in zone 4 and is an aquatic plant we are in zone 5b so i know it will thrive. Along with using the pool for the lotus plant we hate mosquitoes and thought to use the pool as a way to start this ecosystem using the pool for both sources to aid in food supply and rid unwanted pests (mosquito larvae), It would also provide a way to let the bees nest on the leaves to drink the water instead of trying to land on the water and end up dead. As i read this read i soon realized that i would become over populated with this amazing fish, so i would most likely need to get another fish in the pool to control the population, do you have any suggestions? Also my husband i were thinking algae eaters as well to control the waste in the pool and yes in the pool it has a filter but it is the mid-upper portion of the pool and i worry about the holes draining the pool it would be a cycle of constant refilling. And what about the winter time? Do they need a water heater in the pool so it will not kill them or would i have to move them indoors?
We are open to any suggestions. Love this thread please keep us informed! Ty so much!
The pool should be fine for keeping them, but you want to position it away from any trees (to avoid falling leaves), but also to give it at least 5 hours of direct sunlight for the plants. However, you don’t want too much sunlight to keep the temperature regulated – especially since it won’t be in the ground.
As for the rest of it, you’re overthinking it. You really only need the one fish in your pond, and you don’t need to worry about waste or fish to control the population. You’ll likely encounter predators during the year, and it’s not unusual to lose fish to birds, raccoons, etc. Although, depending on the pool depth, you may be mostly safe from birds as it would be too deep for them to stand in it. Also, algae eaters don’t control waste, but if you’re worried about it, you could get snails. But be warned – many snails eat plants, though Japanese trapdoor snails may be your best bet.
They would definitely need either a heater, or to be brought inside during the winter. Decent heaters cost a fortune, and if you’re pond isn’t going to be inground, then you’re best to bring the fish indoors. You can keep them in tubs in the basement with sponge filters relatively cheaply. It’s what I normally do with my pond fish.
As for the holes, why can’t they be patched? That would be the easiest solution in my mind.
Finally, when it comes to stocking, I would start relatively small. Maybe a few dozen in the pool, until you’re sure everything is going well. You’d be shocked how fast they procreate during the summer, and before you know it, you could have hundreds of fish. I’ve seen people keep them in rain barrels, and at the start of the season they just have three or four, and by the end they can have almost one hundred.
Plus, if anything goes wrong, you haven’t bought lots of fish that are just going to die.
I hope this helps.
Also how many fish do you recommend we start with in a pool of 24 ft round pool?
I recently got some mosquito fish 1 month ago like 15 and having trouble with them not reproducing there in a small kiddie pool pond?
The females can delay birth, if they can’t get away from the males. If you add plants, or decorations to the tank where they can find shelter form the males, you should start to see some reproduction. Also, they may be breeding, but just eating all of the young.
Hello,
I am a student looking to do some research using Mosquitofish. I was wondering how many mosquitofish can fit in a 10 gallon tank and how much (in terms of grams) each fish should be fed and how many times a day. Any information regarding these topics would be very helpful. Thank you
A good rule of thumb is to keep one inch of fish for each gallon of water. And since they grow to close to two inches, I think between 4-5 should be alright. But you’ll need to keep on top of water changers, and will also need a plan in place to deal with the inevitable fish fry.
As for the feeding, unfortunately I don’t have it down to an exact science. If you can handle some folksy advice, feed them only as much as they can each in 2-3 minutes. Anything more, and you’re overfeeding them. And you probably won’t find much better advice than this. From what I’ve read, each fish manuals used in scientific experiments just state not to feed them more than they can consume in a short period of time.
Thank you so much for the information. One final question. For the tank cleaning, do you think changing 50% of the water a week would suffice?
In the lab I work in we do it once a month and we have a filtration system. What kind of research are you doing? That will have an impact the frequency of water changes.
50% would be far too much, and you should stick to around 15-20% percent if you’re doing it weekly. Otherwise, you may shock your fish with the sudden change in water; Plus, it’s hard to keep the temperature stable with a change that large.
can mosquito fish be kept in an aquarium with self cloning marbled crayfish?
These crayfish are a bit of an odd-ball when it comes to crayfish, and they really prefer to eat plants and not fish – unlike virtually all over crayfish. Still, you may lose some fish with them, as there are some reports of them eating fish. But aside from the dwarf crayfish, they are probably the best choice for a community tank.
I recently got 4 fish from my school and they are living perfectly fine in a 1 gallon container. Do you think my fish will die soon? Also, I have 2 males and 2 females. The females have been a little bit inactive.
It will definitely be hard to keep the tank clean for them, though mosquitofish can endure some pretty awful conditions. You should definitely add a small sponge filter, or at least a bubbler, and change the water every few days. That way, they’ll at least have a chance.
Please tell me all the information to know because I am a zero-experience fishkeeper.
There’s not much more to say than what’s in the article and what I said. Make sure you change about 20% of the water every few days, and the water should be treated with conditioner to remove any chlorine. Make sure not to overfeed, as overfeeding will be deadly in such a small tank; Only feed them as much as they can eat in around two minutes. Also, you should at least pick up an airstone and an airpump, to help aerate the tank.
That’s about all you can do with a tank that size.
I recently got two mosquito fish, a male and a female. One appears to be pregnant, if she is not, how long should it take? Also, how long can they live on their own for, I am going away for a bit and want to make sure they don’t die. Do I need someone to feed them? I have elodea, duckweed, pebbles, and algae. They have been fine for about 3 weeks. Thanks! Reply before tomorrow!
How long are you going for? You may want to buy one of the vacation feeder blocks if you’re going to be gone for more than a few days. They can go a few days, but anything more than that, and you could start losing fish – which unfortunately would fix the food problem.
Does the female have a dark spot near the anal fin? That’s called a gravid spot and it means she’s pregnant. If she doesn’t have it, then she’s not pregnant.
Thanks, but sadly I must report that the female was pregnant, but I put a third one in there and it’s water must have been contaminated because within three days, they all died. I am getting Betta fish, though!
I’m sorry to hear that. It always sucks to lose a fish – never mind a pregnant one.
Hi I caught a mosquitofish at a pond nearby and I have it in a cup with the same water from the pond I want to know what they mostly eat.BUT IM ONLY 12 and my parents don’t really want the fish in the house so I don’t know what to feed it.I also don’t think the will buy food for the fish.can you please help me.can they eat bread?
First of all, they will need something bigger than a cup to survive in. Do you have a plastic shoebox or anything? They need a lot more water than cup. Also, the water will have to be treated and changed regularly and should be filter.
But if you’re not open to returning it back home, then you can feed them tiny slices of vegetables like zucchini and cucumbers, and also tiny pieces of raw fish (make sure it’s not freshwater fish so you don’t spread disease). Both of those foods are easily found, and I often make my own food out of those along with some other ingredients.
I hope this helps.
i have givin it to my friends mom and she has an aquarium i gave it to her the next day after i cought the fish thanks for the advice i will tell her she can make that for the fish thanks.
I want to own a female fish, but I don’t want it to give berth. What do I do??
There’s not much you can do for livebearers. Even when you buy them, odds are they’re already pregnant. The only true way to do it is to only keep males (which is problematic for aggression), or females (which will usually give birth to males and mate with them). I wish I could help more than that.
I also own a male fish too.
Hi. I love your site. It is very easy to understand your info. I have a question I haven’t found any info on yet. When the females have the black spot on their rearend, it means they are pregnant. But does the black spot disappear after giving birth? One of my females have had 3 pregnancys before I got her separated from the males. It has been awhile now, at least 6 mos. But she still has the black spot. Is it supposed to disappear or am I to worry about her having more babies? Thanks.
There will always be a slight dark colouring on livebearer females, and it will grow and become darker when the female is pregnant. And you should be safe from seeing any more babies – as long as there are no other males or even young males in the tank.
P.S: I’m glad you’re enjoying the site. 🙂
I have a 50 gallon rain barrel that has a shallow basin (about 3″ deep) on the top that I poked holes in and rigged with a fountain to re-circulate water from inside the barrel. I filled the basin with some river rocks and was hoping to add a couple of fish to help keep mosquitos from breeding. The water level stay pretty constant around 3″, is this deep enough for mosquito fish?
I would put a thermometer in there for a few days to keep track of the heat. With water that shallow outside, heat could become a real problem. Beyond that, the water should technically be deep enough for the fish, but I could foresee a lot of potential problems.
Hay i just got a few of thees little guys and thay gave birth but i got one that was pregnant but not given birth yet, and one thet had just given birth mixed up in the tank of males. is there a way to tell witch one has given birth alredy and witch one has not
It should be easy enough to tell — the female will have a swollen belly, with a black area by the anal fin.
I bought 5 small mosquito fish at the pet store and put them in a curved ceramic bowl, 11 1/2″w and 4″h, overnight as it was too dark to go out to the pond. In the morning I found 3 had jumped out and were already dead on the carpet. I had used the water they came in and added tap water that was filtered. It was sad. Why would they have jumped out as they seemed happy swimming around and resting when I left them for the night. Should I have fed them? I was waiting as there were lots of mosquito larvae in the pond.
Usually when they jump out, it means there is something wrong with the water. The water would go badly very quickly in an aquarium that small. The best thing to do is to transfer them to something larger as soon as possible.
What kind of fish flakes in particular would you recommend?
I personally really like Newlife Spectrum and Hikari fish food. Both of those foods are excellent quality, though it’s often a bit harder to find Newlife food.
I have 1 mosquito fish in a 10 gallon tank and added 5 new ones. All five new fish died within 2 weeks. Original fish still going strong. Afraid to add more if I am doing something wrong. Tank has filter and water is treated. Grateful for any advice.
There are two possibilities: either the fish were already sick, or adding that many fish caused a mini-cycle and killed the fish.
When buying the fish, always try to buy them from the best tank you can find. The tank should be clean, with no dead fish, and no visibly sick fish.
Also, next time you add fish, try to add no more than 2-3 at a time. Adding to many fish at once can overwhelm the beneficial bacteria that break down waste. And if the bacteria can’t break down waste fast enough, there is an ammonia and nitrites spike – both of which are lethal to fish. Store bought fish are usually weaker and more stressed than fish that have been in an aquarium for a while. So it may explain why they died and your other fish didn’t if there was a mini-cycle (ammonia spike).
Hi, I have a small pond with 4 goldfish, and 10 mosquito fish. Within a month, I now have about 40 mosquito fish. The really small babies we being harassed and nipped by the bigger babies. I only have a small (3 Gallon) tank, but I was wondering if I could put the really bullied ones in there and care for them until they get bigger, then put them back in the pond.
You could do that. Just keep an eye on your water quality, and make sure you don’t have too many in there. Too many fish in a tank will require very frequent water changes with a good water conditioner.
Mosquito Control in our area gave us a larger Mosquito fish 1 1/2” who we’ve had for a couple months. After giving birth we removed her from the fry for awhile and then put her back in the 30 gal horse trough with the others. She was ok for awhile but the last 3 days has been sideways (not dead yet) on top of the water. It appears she’s lost her rear fin mobility. When we add fresh water (a gallon or 2) for the livestock, she will dive down to the bottom of the tank and then floats back up to the top. What can we do to help revive her? The fry and one other smaller mosquito fish are also in the tank and seems to be doing fine.
It sounds like a problem with the fish’s swimbladder. I would lightly blanch some peas, shell them, and then feed them to the fish. This often clears up swimbladder problems. Also, if you’re feeding flake food, soak it for a bit beforehand, so the fish doesn’t swallow any more air which can make it worse.
Let me know if this helps.
Thank you, Robert. It’s worth a try. I’ll let you know.
I tried bits of peas in a separate, smaller water bucket where I secluded the mosquito fish from the bigger trough. Trying to get her to eat is challenging and I’m really not sure if I succeeded. But the inside of the peas are in the water and she has no competition for them. She might be too far gone. I’ve been reading up on swim bladder and I am sure that’s the issue. Some of the previous posts mentioned swim bladder but I didn’t know enough to realize what swim bladder was. She does not appear to have any parasites so I’m not sure where she got it from but a couple of months ago we had a couple of mosquito fish die with the same symptoms. Would you recommend occasionally throwing a couple of peas in the trough with the others? Thank you so much for your help!
I like to feed vegetables, like peas, to all but my carnivore fish regularly. The additional fiber really helps to keep the fish healthy.
However, if you’ve had other fish die with the same symptoms, it may be bacterial. What does the fish’s poop look like? It is white and stringy? Are the scales standing up like a pinecone?
The mama Mosquitofish died unfortunately. Others that have died had darkish/black poop. We clean the trough about 1xwk. but leave a little algae in there w/some rocks. After I clean I do supplement w/flakes.i always wait several hours after I clean before putting the fish back in. Once in awhile I’ll clean the trough w/white vinegar but always really thoroughly rinse.
I’m sorry to hear the mosquitofish died. What sort of water are you using in the trough? Are you treating it?
At least from the consistency of the poop, it doesn’t sound like it’s a bacterial infection.
We are using culinary water In the pump for our animals out back. One idea I had was that I use an insecticide in the corral to keep down the flys which is about 3 yards away from the trough but part of the barn is blocking where I spray & the trough. Maybe I have insecticide on my work gloves when I refill the trough or something? How sensitive are fish to insecticide? BTW- I really appreciate you taking the time to help me.
That could be it. Fish are typically very sensitive to chemicals in water. Most insecticides are neurological agents which could possibly explain the erratic swim behavior (loss of nerve control)
There are three possible problems:
1. The insecticide may be poisoning the fish.
2. Culinary water is often chlorinated. I don’t know if you’re treating the water to remove it.
3. The water is probably fouling pretty quickly from fish waste unless the trough is quite large and is being filled regularly. Is it a smaller trough or one of those monster ones?
Thinking back the last couple years, there is a correlation of when I started getting aggressive about combating the flies w/ insecticide and I have not thought about chlorine in our smallish (appr. 30 gal) trough. As a non-fish person, being on this site has given me a whole different perspective. The Mosquito Control Dept’s (who gives me the fish) philosophy is that they are totally utilitarian and at the end of the season, you are supposed to just dump out the fish. When they gave us the bigger mama fish, I stated feeling a lot differently. I don’t want to repeat this problem next year because there are too many factors out of my control but I am considering getting an aquarium in the house where I can provide a proper environment for fish. Thank you So much!
I have a small pond (approximately 250 gals.) and had many (40ish) mosquito fish for many years. Overnight they were all gone except for 2. What could have happened? The day before they didn’t seem to be eating very much. Usually it’s a feeding frenzy. I feed them goldfish flakes. The only thing I can think of that I have been doing differently is using rain water to fill the pond instead of tap water with the stuff to remove the chloramines. They have been reproducing like crazy. Now they are almost all gone.
It sounds like you were hit by a predator. A hungry raccoon or bird can wipe out a pound. What’s the layout of the pond like? Could birds easily stand in the water or could animals reach in from the sides?
What’s the maximum amount of mosquito fish for a 20 g aquarium I have 2 quarter sized red eared slider turtles and they like to chase them around and eat them i was just wondering b/c I basically have unlimited access to them since I livee right by a creek and I breed them in a fairly large plastic bin
The problem with a setup like that is the turtles are already very dirty animals. And if they’re eating the fish, and you’re adding more fish, the water will quickly foul. I wouldn’t add more than a handful, and even then you need to keep on top of water changes and keep a close eye on the water quality. Also, you say it’s a 20 gallon, but I assume it’s not completely filled to give the turtles some access to land?
I now have them in a 175 gal that is huge and filled all the way up. And has quite a bit of land for them to bask in and sleep if they wanted but now I don’t know what kind of fish to put in there I’m thinking one of my red tail catfish or tiger shovel nose but I don’t really knkw. my mosquito fish are in my old
20 gallon and they really like live plants and algae but I no longer use the toat so I’ll take the pregnant ones and put them in a 10 gal then let them give birth then take them out and wait a while be for I put them back in the 20 and just repeat the process and now I’m breeding crayfish and feeding my turtles the babies because there way easier for them to catch and I think I’m gonna get a pleco for the turtle tank also
I’m curious about the breeding of crayfish and what special care that takes as well
hi my sons fish died they came from a class project they live in a 2 liter with plants in water and on top growing in soil.they seemed happy they had babies just now but when we woke the next day adults were dead babies alive what happened and what do we do now?
It’s probably a water issue. The water quality can decline very quickly in a container that size. To keep fish happy in an environment like that, you need to change the water almost daily. If the babies are still alive, you should try to get them into a proper aquarium that’s at least 5 gallons and has proper filtration. If you want to keep them in there, try to change the water at least twice a week (25% at a time) and replace it with treated water (all chlorine removed).
I have had my fish for about a year now and got him from a school project. He has been alone in a one gallon bowl and has thrived in it. I have an algae ball that filters out the waste. I clean the bowl every one an and a half weeks. He is super happy, even though you said I had to clean it more often and give him a more water to live in. He also has no filter. This is not how you described… Do you think this would be consistent if I put another mosquito fish in the same conditions? But not together with each other. It is sort of confusing how he is so resilient.
Also thanks for all of the great tips and info!!!
A second fish would definitely be too much in a bowl like that. If you test the water right now, I’d wager there would be ammonia and nitrites in the water. It’s almost impossible to keep the water properly clean in an aquarium that small. And while it won’t kill your fish, even small amounts of ammonia and nitrites will significantly shorten a fish’s lifespan in the long run, along with a host of other side effects. If you add a second fish, it will only make the situation worse. My recommendation would be wait until you can get something large for your fish.
It will also help your fish if you can start doing water changes twice weekly (I know it’s a lot of work). But that will give it the best chance of a long life in a fish bowl.
So glad I found this site. Like many of the comments, my daughter came home with mosquito fish and snails from a school project, 5 fish, including one expecting female. All but one fish (including the female) literally disappeared, and are not in the filter, my daughter says they were eaten by the snails but….my question is, is the one alone in the tank ok to live alone? He’s the craziest fish I ever seen. The fish we have had thus far, although not many, were aloof, but this fish follows us as we move around the tank and comes quickly when we look in. He swims back and forth like crazy, likes he’s trying to communicate. No I’m not crazy, but it seems he is lonely and looking for attention. Or am I reading too much into it, and mosquito fish are fine to be alone? Thanks for any insight.
Mosquitofish aren’t a shoaling fish, so they generally do alright when kept alone. And your fish doesn’t want attention – he wants food. That’s very common begging behavior in a fish. 🙂
Thank you for your response!!!!
That’s funny he’s not looking for attention because now I talk to him all the time!
I was just online looking for fish toys fearing he (Gilly) is bored! Do you recommend fish toys?
and thanks again. your insight is very helpful and appreciated.
What sort of toys were you thinking of?
It’s a bit icky to some people, but mosquitofish (and many other fish) really enjoy hunting live food. Nothing seems to make them happier than chasing live food around their aquarium. Many stores sell live foods (blackworms and brine shrimp) and there are many you can easily culture on your own. But like I said, it’s not for everyone. My wife hates when I feed blackworms to my fish.
My fish kept swimming to the top of the tank then floating down to the bottom. What is going on?
It sounds like it might be a swim bladder problem. Try lightly boiling some peas, shelling them, and then feeding them to the mosquito fish. If that doesn’t fix it, it might be illness. Are there any other symptoms?
What should I feed my fish. I have elodia as well as duckweed.
Mosquito fish can be fed any of the fish foods in the store. I personally like Newlife and Hikari food. Also they should regularly be fed live or frozen foods and they especially love bloodworms and blackworms. And no surprise here – they love mosquito larvae – assuming it’s legal to culture it in your area.
Hello my son got a mosquito fish from his school. He wanted more fish to go along with his one fish, so I went I got him two fishes which were minnow fishes will I put those fishes in with the mosquito fish and the next day the fishes were dead. I let them adjust to the water and all. I don’t know what happen do you think the mosquito fish did something to them and also I want to get more fishes but I don’t want any female mosquito fishes so will the male mosquito fishes get alone with each other. And how much can I have in a 1 gallon tank .
I doubt the mosquito fish could have killed them. A death that quickly is either a problem with the water or the fish were already sick to begin with. First, check you water. If you take a water sample to a pet store, many of them will test it for free. If the aquarium water is fine, then the fish were likely sick when you bought them. When you buy a fish from a store, always look at the tank first. If there are any sick fish, dead fish, or fish that seem lethargic, don’t buy the fish from the tank.
But since it’s only a one gallon tank, it’s likely the water quality is the culprit. It’s very hard to maintain good water quality in an aquarium that small and you should aim to upgrade to a 5 gallon in the future. Mosquito fish are fine on their own and you should consider only keeping the mosquito fish until you are able to upgrade the aquarium. If you add any more fish, the water will likely foul very quickly.
My Daughter was sent home with 2 mosquitofish 1 Male 1 female) from school, they have been fine since October, Now Feb we came home and we found it on the counter, We’ve been trying to figure this out. Can anyone explain.
It’s pretty common for fish to jump out of their aquarium. The best way to combat that is too make sure it’s property covered, with no major gaps for the fish to jump out. Over the years, I’ve lost more than a handful of fish this way, and it seems some fish are just intent on jumping out. However, I would also check the water quality, because sometimes they jump out when the water isn’t perfect.
Why do mosquito fish eat their babies?
Unfortunately, it’s pretty common with most fish. Even well fed will often take the chance to eat their babies. It’s part of the reason the females hate to have their babies around other mosquitofish and try to find seclusion. One way to help babies survive is to provide dense floating plants or thick substrate plants like Java moss.
Hi Robert, I recently caught and have been trying to take care of a bunch, maybe 25 eastern mosquito fish by where I live in NJ, and was wondering if if there was a way I could send you a picture of my setup for tips and recommendations for tank improvements, I also have some questions about breeding, I’m pretty sure I have a bunch of pregnant fish after reading and rereading this article, I even separated three in a breeder box hanging over outside of the side of the tank, so if there is an email address or website I can send pictures to and back and forth with you, please let me know! Thank you for writing this article and I hope to be in touch soon
Sure. You can send them to aquariumtidings@gmail.com
Just wondering if you recieved the emails I sent? They maybe a little dated now because it’s been a few days but I’d still like to ask you a few questions
I have maybe 20 mosquito fish fry from at least 3 different females and was wondering what kind of care/environment would be best for them and I was wondering if you knew anything about the care of (what I think they are) eastern black nose dace, and the Johnny darter, all three kinds of fish were caught in the same stream and or pond, idk if that info helps
My mosquito fish my pond eat anything and have out numbered plenty of bigger fish in the pond and are absolute predators eating things as big as spiders and birds. (Not kidding)
In my pond*
What are some good plants the baby mosquito fish can hide in?
Java moss is by far the best choice in my opinion, as it provides both small amounts of microscopic food and provides dense cover for the fry. Beyond that, I like to use water lettuce, cabomba, anubis, hornwort, and water sprite.
I have a 35 gallon, outdoor, heated pond. Made it for a small betta sorority, and ember tetras, but I also got two mosquito fish when I first added the fish because there was plenty of larvae to go around. I added the mosquitofish and ember tetras first, about two months ago. One mosquito fish is a girl, and one was a boy. After about 2 days, I never saw the boy again. There was some rain and a little overflow, but none of the other fish have ever disappeared over the edge when it has rained.(southern california.) So for the past nearly two months I thought it was just the female mosquitofish, the tetras, and then I added 3 bettas to start my sorority about a month ago. HOWEVER, now over the past 2-3 days I have begun to see around 5-10 (what I believe to be) baby mosquito fish. At first I thought impossible because of the timing, but they are dark, and could not be ember tetra fry. Could she have been waiting for the right conditions for around two months?? Or could the male somehow be hiding in the (less than a foot) depths, and been avoiding my sight during feedings all this time? Been able to consistently account for everyone else though(except for a male african dwarf frog that I didnt mention but havent seen in a month either.) The fry I do see appear to be happy and healthy! Happy only about 5 have gotten through. Thought she had been getting a little fat, but ended up just being a miracle lol
It could be two things – the female could have delayed giving birth until she felt ready, or the male could have been hiding. My money is on the female delaying the pregnancy though, as they’re not noted for their hiding abilities.
I have never seen nor heard of a Gambusia male with a bright red tail! Where do you get that information from?
I have a giant stack of books I’ve built up over the years, but a lot of the information is from personal experience. I love fish native to north America and have kept mosquitofish in aquariums and ponds. It’s pretty common to see the red tail in mature and healthy male mosquitofish.
Hello,
I am a teacher and I got 30 mosquito fish for a school project. I was not comfortable putting them in a coke littler bottle, so I bought them an aquarium and brought them home.
They keep doing their thing and now I have over 20 babies :s (The first 17 were eaten by mom).
How can I get rid of some of them? To be clear I do not want to kill them or do something inhumane.
I already upgraded the aquarium, but I can’t keep buying more stuff.
Thank you in advance for your help.
That’s always one of the biggest problem with the more prolific fish in the aquarium hobby. One good way is to offer them to local pet stores. Sometimes they will take them off your hands for free to sell. Otherwise, try local forums and groups to see if anyone would want them.
You cant throw fish in water. I see people at Petco buying tanks and fish at same time. Google the process
How do I tell when/how the female is pregnant
A dark area called the ‘gravid spot’ will appear just behind its belly, and the belly will become quite distended over time.
I have two pregnant mosquito fish in a tank. Should I seperate them? There are no males in the tank.
It has been great reading the contributions above, Thank You.
The County Mosquito/Vector Control brought some fish to me, [since with equipment failure and WITH the CA drought, it has pushed me into the decision to eventually remove my pool; originally (16K G) now probably 10K with evaporation.]
When the fish were brought to me, chlorine neutralizer was added. Initially 10Ks of larvae in (almost black) Dec in the pool (I was embarrassed).
Until the concrete is removed, no more filtering or chemical expenses for me, I am aerating though. Very successful “breeding”.
It is difficult to see mosquitos, AND no bites. No complaints from neighbors.
I will give back fish to the County (or other neighbors who decide to make the same decision) if they want some.
I’ve got four females in an aquarium with other fish that are pushing three years old. No males have been present for at least a year. None of them have ever borne. Yet I could swear that three of the four are pregnant, and have been for a LONG time. Distended belly, large gravid mark. Is this possible?!? Or do they just look like that when they get really old?