Fishkeeping can be a difficult hobby to master. Not only do you have to learn about the wildly different needs of fish species, but you also have to manage a carefully balanced, miniature eco-system.
And just when you think you have it all figured out, you learn something you’ve been doing dutifully for weeks – or even months – has been harming your prized fish. Needless to say, this can be disheartening, and to help you avoid this, I’ve compiled a list of the most common mistakes people new to the hobby make when caring for their fish.
1. Feeding Your Fish too Much
Let’s face it, fish aren’t nearly as interactive as a cat or dog, so it’s only natural to look forward to feeding time – one of the only times you truly get to interact with your fish. After all, who can resist a fish begging for food along the front of an aquarium And what’s the worst that can happen?
Unfortunately, overfeeding fish doesn’t just lead to obesity – it often leads to illness and death. When you provide a fish with more food than they can eat, the food sinks to the bottom, where it starts to decompose. And when it decomposes, it releases harmful chemicals into the water.
Usually, if you only overfeed a little bit, the beneficial bacteria can handle the additional load (if you want to learn more about beneficial bacteria, read The Complete Guide to Cycling). But when you consistently overfeed fish, ammonia and nitrites start to build up unchecked, and you quickly end up with a real problem on your hands.
So no matter how much your fish beg, you need to limit the amount of food you provide to your fish. A good rule of thumb is to feed them as much as they can consume in three minutes. Any more than that, and you’re probably feeding them too much. If you want to learn more about feeding your fish, read How Much and What to Feed Aquarium Fish.
2. Not Using a Filter
While the idea of not using a filter would seem ludicrous to a more experienced aquarist, it’s actually fairly common for someone new to the hobby to be unaware they need one. Underpaid, under-experienced pet store staff don’t do a great job of making sure you’re prepared for when you take your first fish home, and unless you know where to look online, you may not even realize how integral a filter is to a fish’s health.
While there are a few setups that will work without a filter, most notably a Walstad Planted Tank, most of the time, if you don’t have a filter, at best you’re condemning your fish to a shortened life. At worst, you’ll be forced to watch as fish after fish goes belly up.
What is difficult to see in an aquarium without a filter, is the slow build-up of toxins that will first injure and then sicken fish, before finally killing them.
A filter allows a limited nitrogen cycle to occur, and beneficial bacteria growing on the filter converts harmful chemicals like ammonia and nitrites, into less harmful nitrates. Nitrates which can then be removed during water changes.
If you don’t already have a filter, then it’s something you need to get right away. I’d personally recommend an Aquaclear Power Filter, but no matter which filter you choose, it’s one of the most important components in a healthy fish tank.
3. Not Treating Tap Water
This is something that comes up quite regularly when talking to people new to the hobby – they don’t realize they need to treat their tap water. Now, not everyone needs to treat their tap water. Most wells don’t have chlorinated water, and in rare instances, certain water supplies use ozone, not chlorine to treat their water. If you have either of these water sources, you probably don’t need to treat your water (though with well water, you should test it for harmful metals).
But if you do have chlorine in your tap water, or chloramine, then you absolutely must treat it before adding it to an aquarium. Not only can it injure your fish, but it will also kill off the majority of the beneficial bacteria in the tank. The loss of bacteria will cause a spike in ammonia and nitrites, and it’s doubtful already weakened fish can survive a mini-cycle.
To treat your tap water, all you have to do is add water conditioner. A good choice is Tetra AquaSafe Plus Water Treament, which not only neutralizes chlorine, cloramines, but also heavy metals that can be harmful to fish.
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4. Incompatible Tankmates
Introducing incompatible tankmates is one of the greatest problems aquarists encounter at all levels of experience. Even when you think you have fish that should get along, a normally docile fish will start to act aggressively, or a species of fish that usually rules over a tank, is attacked and bullied into submission.
But when you’re still relatively new especially, it can be hard to figure out what fish go well together, and while pet stores have been improving in recent years, they often recommend fish that have no business being together.
If you have one fish that is constantly attacking others in the tank, then you could be harming your fish by keeping them together. Overtime, attacks can lead to heightened stress, which often leads to illness. And that’s assuming there’s no real damage from the attacks, including torn fins, or lost scales – both of which can become infected.
It’s important to keep an eye on an aquarium after adding new fish, and to have a backup plan in place in case things aren’t going well. And before adding any new fish, do your best to find out if they can co-exist peacefully together.
5. Not Changing Aquarium Water
I was recently exchanging e-mails with someone, who complained his fish were constantly flashing (high-speed rubbing) on the gravel and ornaments in his tank. After he sent me some pictures of the fish, and I was able to rule out the most common culprits like ick, I asked him how often he changed the water.
What I received back was the e-mail equivalent of a blank stare, and all it stated was, “change the water?” And surprisingly, this isn’t an unusual response. Many people, both new and experienced, don’t realize they need to change a portion of their tank water every week.
When you don’t change the water, nitrates continue to build up in the fish tank. While nitrates aren’t harmful to your fish at lower concentrations, they can start to irritate fish as their levels rise, and can cause increased stress and illness.
A good rule of thumb is to change 15% of a tank’s water every week, though you can safely go up to about 30% a week without encountering any problems. And always make sure to treat any new water being added to the aquarium.
6. Putting Unsafe Objects in the Aquarium
There is a simple rule experienced aquarists live by: don’t put anything in your tank that you don’t know where it came from. Whether it’s live foods, or rocks, if you don’t know the history of the object, don’t let it touch your aquarium’s water.
Of course, this isn’t something most fish keepers know, and I constantly hear from people who’ve added something new to their tank, only to experience a disaster of biblical proportions. From toxic rocks, to live foods contaminated by pesticides, the list is endless and heartbreaking, as people see their years of hard work wiped out almost overnight.
Always stick to objects you personally collect, or purchase from a reputable pet supplier. Anything else is just too risky to add to your fish tank.
7. Adding too Many Fish at Once
If you’re familiar with the cycling process, then you already know it’s a bad idea to add too many fish at once (read more about cycling here). But many people new to the hobby only vaguely know about cycling, and they often make the mistake of dumping new fish in, all at once.
Unless you have a reason for adding all of the fish at once – like you’re trying to setup a tank with highly aggressive, territorial fish – then you should only add a handful of fish at once. With smaller fish, a good rule of thumb is to add no more than three at once, and with larger fish, only one at a time.
This gives the biological filtration in the tank time to adjust, and prevents a mini-cycle from occurring – something no fish keeper wants happening. When you add too many fish at the same time, it overwhelms the biological filtration, and you’ll have a spike of ammonia and nitrites.
These are a few mistakes people commonly make without realizing it, but thankfully, all are pretty easy to remedy. Like any other hobby, in fishkeeping, you learn from your mistakes. And you hope you don’t hurt any of your fish in the process.
Let me know in the comments some of the mistakes you’ve made without realizing it in the past.