When most people first get into the fishkeeping hobby, they often choose a small aquarium to start out with. And it’s easy to see why: small aquariums have attractive designs, fit easily on a desktop or a counter, and will often cost a lot less than the larger alternatives. But choosing a nano aquarium (generally defined as any freshwater aquarium under 10 gallons) greatly limits stocking options, as only a handful of fish will thrive in an aquarium that small.
So what fish will thrive in a 5 gallon aquarium? And it’s important to emphasize the word thrive, rather than just survive. There are numerous fish that will survive in a 5 gallon aquarium, but they’ll often be unhealthy or unhappy for a variety of reasons. Some fish won’t have enough room to swim in a nano tank, while others are only happy when kept in large schools. It’s important to remember just because a fish can survive in an environment, doesn’t mean it should be kept in there.
With that in mind, listed below are some fish – and quite a few invertebrates – that will thrive in a nano tank.
Goldfish aside, bettas are probably one of the most misunderstood fish in the aquarium hobby. While tales of them surviving happily in a puddle are rife on forums and websites, they actually require a fairly large, heated, and well-filtered aquarium. And that makes a 5 gallon aquarium the perfect environment for one.
However, only one betta should be kept in a 5 gallon aquarium – either a male or female – otherwise they will fight to the death in such a confined space. Also, not all 5 gallon aquariums come with a heater, so it’s important to add a heater that’s specifically designed for small aquariums. Bettas are a tropical fish and require tropical temperatures.
Endler’s Livebearers (Male’s Only)
Endler’s Livebearers are a wonderful little fish that will thrive in a 5 gallon aquarium – but only if just males are kept. These fish are a species of guppies, and like guppies, they reproduce at astonishing rates. If both males and females are kept together in a 5 gallon aquarium, the fish tank will quickly be overrun with fry (baby fish).
But a handful of male Endler’s Livebearers will live quite happily in a 5 gallon aquarium. Live plants should be provided to divide the tank into separate areas, as males will occasionally act aggressively towards each other. The plants help to break the male’s line-of-sight and should prevent any significant aggression.
While dwarf puffers can be kept in a 5 gallon aquarium, it should be noted that they are a difficult and demanding fish to keep. They require excellent water quality – something difficult to achieve in a fish tank this small – and they are strictly carnivorous and will often refuse prepared food.
But if someone is willing to take on the challenge of dwarf puffers, then a pair – and no more than a pair – can be kept in a 5 gallon aquarium. Live plants and decorations should be provided to create hiding places for the dwarf puffers, and live plants have the added benefit of helping to maintain the water quality.
The Mexican dwarf crayfish is a bit of anomaly among crayfish – it’s relatively peaceful and doesn’t spend every moment of its existence trying to escape its aquarium. Because of these traits, it makes an excellent choice for a nano aquarium. A single Mexican dwarf crayfish will live quite contentedly in a 5 gallon aquarium.
However, only a single Mexican dwarf crayfish should be kept in a 5 gallon aquarium, as they become virtually defenseless during molting. And in a small aquarium – even with adequate hiding places – they probably won’t be able to avoid the other crayfish when molting and will most likely be eaten.
African Dwarf Frog
African dwarf frogs are among the most popular choices for nano aquariums. Not only are they hardy and easy to care for, but they are fun to watch as well. They often blunder around the aquarium, trying to eat anything that fits into their mouth, while wrestling harmlessly with the other frogs.
Because of their poor eyesight and tendency to try and eat anything, shrimp and small fish should be avoided in aquariums with these frogs for obvious reasons. A handful of these frogs will be quite happy in a 5 gallon aquarium, and they tend to be very forgiving of any mistakes, making them a top choice for anyone new to the hobby.
Shrimp are another top choice for nano aquariums, and most species are incredibly easy to keep in a 5 gallon aquarium. Some species, such as red cherry shrimp, will also breed prolifically and can be easily sold to bring in some extra money.
The best shrimp species to choose for a nano aquarium are red cherry shrimp, ghost shrimp, and red crystal shrimp. All of these are relatively inexpensive to purchase and are fun to watch as they travel around the aquarium, feasting on biofilm and climbing anything they find.
While snails might not be as exciting to watch as some of the other entries on this list, they still do quite well in a nano aquarium. Some of the larger species, such as apple snails should be avoided, as they grow so large, they can quickly foul the water of a 5 gallon aquarium. But many species of snails will thrive in a nano tank, including ramshorn snails, mystery snails, nerite snails, or even some less traditional choices like greater pond snails, Japanese trapdoor snails, or Malaysian trumpet snails.