5 Fish for 2 & 2.5-Gallon Tanks (With Pictures)

For fish enthusiasts and amateur aquarists, fish and fish tanks are a bit like potato chips – you can never have just one! Fishkeeping can be an enjoyable yet addictive pastime, with so many different shapes, sizes, and interesting species, all with their own specific quirks and needs. A common misconception is that fish are low-maintenance pets that require little in the way of care and interaction, but this simply isn’t the case. Filling a bowl with water and chucking in a couple of goldfish is easy enough to do, but it would be the aquarium equivalent of keeping your canine chained up in a shed and considering yourself a dog owner. You might feed it and keep it alive, but you’re not providing it with a good quality of life.

Although fish aren’t as demanding as cats or dogs when it comes to daily interaction, feeding, exercising, and picking up poop, they still require our attention, with tank cleaning, landscaping, water quality checks, and water changes just part of their regular upkeep. And just like a prospective dog owner needs to assess the size of their property, lifestyle, and other pets before getting a new dog, it is vital to familiarize yourself with the habits, preferences, and environmental needs of any fish species before bringing them home.

Some fish are better kept on their own, while others do better in larger groups. Many fish prefer water that is constantly moving, while some can become exhausted to the point of death if the current is too strong. One aspect of fishkeeping that is important for all fish species is that size does matter. Most fish need more space than you might think, even if they aren’t the most active swimmers. The volume of water needs to be enough to keep waste products, chemicals, and oxygen levels in balance; some fish need a deeper tank to mimic their natural habitat, while others need extra length to allow them to swim longer distances.

With all that in mind, you are likely wondering what type of fish are suitable for 2- and 2.5-gallon tanks? Well, the answer is: not many. These small tanks, sometimes called ‘nano’ or ‘pico’ tanks, are popular because they fit easily into smaller spaces, look great on desks or sturdy bookshelves, and are cheaper to stock and maintain than larger aquariums. However, containing only 7.5 to 10 liters of water also means they are not suitable for keeping many fish for long periods.

So if you’ve got yourself one of these tiny tanks, what should you keep in it? Let’s take a look:

Things to Consider for Small Tanks

You might think that it’s just about size – small tank = small fish, and that’s partly true. However, you also need to consider the natural habitat and behavior of the fish you’re looking to keep. Are they fast swimmers? Schooling fish? Bottom-dwellers or top swimmers? Do they need good water flow or minimal water movement?

The fish on our rather short list tend to be peaceful floaters rather than active swimmers, and either don’t require or prefer to avoid fast-flowing water.

Top 5 Fish for 2 and 2.5-Gallon Tanks

1. Betta Fish

Sometimes referred to as “Siamese fighting fish”, these diminutive but decorative fish are relatively easy to keep, but have some very specific requirements. You can keep a few female Betta fish together, but males must always be kept on their own and out of sight of other males – they’re called fighting fish for a reason! Although Betta fish can be kept in larger tanks, they can become fatigued easily and fins can be damaged in high flow water, so they often do better in smaller tanks.

2. Tiny Tetras

Small tetra species like the Ember tetra, Green neon tetra, or Ruby tetra don’t grow much larger than one inch, so they don’t need a whole lot of space, but do like to have some plants to hide in. Tetras are schooling fish, so they are more content when kept in groups of at least six. They are peaceful and are popular additions to a community tank setup.

3. Pygmy Puffers

Pygmy pufferfish, also known as the Malabar pufferfish, dwarf pufferfish, or pea pufferfish, are real characters. You’ll love watching them zoom around your tank, but they’re likely to nip at other fish species, so they're best kept in small groups in your nano tank, or in a much larger aquarium where there is no shortage of space and resources. Pygmy puffers usually max out at 0.8 inches, and aren’t a low maintenance as some of the others on our list, so be sure to do plenty of research.

4. Dwarf Corydoras

As their name suggests, these diminutive fish are much smaller than some of the more recognizable cory species, rarely exceeding 1.2 inches in length. Dwarf or pygmy Corydoras aren’t really suited to particularly large community tanks as they are often intimidated or preyed upon by larger fish. A small shoal of 6 should do well in a nano tank, and being bottom swimmers, may even be joined by a few small top-swimming fish like tetras.

5. Ornamental Shrimp

Okay, technically not a fish, but these brightly-colored crustaceans make for some interesting viewing in a tiny tank. Provided they are kept with small, peaceful fish, they can add a pop of color to a small set-up, whilst providing some cleaning services too.

Final Thoughts

When setting up a 2 to 2.5-gallon tank, it’s important to remember that this is a tiny habitat, suitable for only a few fish species as a long-term home – some of which can even be housed together. These small tanks can make great temporary nursery or hospital tanks for larger fish species, and can also be perfect for tiny shrimp and other aquatic invertebrates.

Featured Image Credit: Thanes Pruttivanichakul, Shutterstock