Best Fish for Small Tanks

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Very small fish tanks have opened up the fish keeping hobby for many people that lack the space for a larger community aquarium. Aquariums that are 2 to 5 gallons give people many options for where to keep their tank.  Whether you are looking for a small tank to go in your office or maybe a tank to go on your kitchen counter top, small tanks open up these options.

There are some challenges associated with looking for the best fish for a small tank as it’s extremely easy to overpopulate the tank.  Overpopulation leads to poor water parameters and ultimately, it adversely impacts the overall health of your fish.

We’ve put together a list of fish that can not only survive, but thrive, in a small tank.

Best Fish for Small Tanks

Betta

Pharaoh Hound [CC BY-SA 3.0]
Pharaoh Hound [CC BY-SA 3.0]
Minimum Tank Size: 2.5 Gallons

Betta fish are the perfect fish for small tanks.  They come in many different colors and varieties which provides many options to find the perfect color and look.

They require at least a 2.5 gallon aquarium.  Their smaller size and small bioload are a perfect fit for these small tanks.  Both males or females will do well.  Males have the large luxurious fins, while females have the smaller fins.

Ember Tetra

By Mbdtsmo [CC BY-SA 4.0]
By Mbdtsmo [CC BY-SA 4.0]
Minimum Tank Size: 5 Gallons

Ember tetras are tiny little fish.  They wont’ grow larger than 1 inch long.  The best part about ember tetras is that they are so small that you can put several fish in a 5 gallon tank.  In fact, they should be kept in a group of 3-4 fish per 5 gallon aquarium as they are schooling fish.

Endler’s Livebearer

By Karen Koomans [CC BY 2.5]
By Karen Koomans [CC BY 2.5]

Minimum Tank Size: 10 Gallons

Endler’s livebearers are another small fish that should be kept in a group.  Live bearers have a higher bioload that other similar sized fish, so these guys will need at least 10 gallons for 3-4 fish.

Guppies

Rchampagne [Public Domain]
Rchampagne [Public Domain]
Minimum Tank Size: 10 Gallons

Much like the Endler’s above, guppies are livebearers which have a high bioload per length. They also need to be kept in groups of 3 or 4 fish as a minimum.

Dwarf Corydoras

AquariaNR [CC BY-SA 3.0]
AquariaNR [CC BY-SA 3.0]
Minimum Tank Size: 10 Gallons

Dwarf cory catfish are the only bottom dweller that have made the list. Dwarf cories should be kept in a group of 3 or 4 in a 10 gallon aquarium.  They will spend nearly all of their time on the bottom of the tank near the gravel so the area of the tank is more important than the volume of the tank.

Dwarf Gouramis

Quatermass [Public Domain]
Quatermass [Public Domain]
Minimum Tank Size: 15 Gallons

Dwarf grouamis are a brilliant orange and blue coloration that often serve as a centerpiece fish in tanks between 20 and 30 gallons.  In smaller tanks, they can live as the lone fish.  The minimum tank size should be 15 gallons as gouramis can reach 3 to 4 inches long.

Best Invertebrates for Small Tanks

Shrimp

TheJammingYam [CC BY-SA 3.0]
TheJammingYam [CC BY-SA 3.0]
There are several different species of shrimp that are appropriate for small tanks including ghost shrimp, amano shrimp, and cherry shrimp.  None of them grow larger than about 1 and ½ inches long.  Shrimp also have a very small bioload considering their size and have the added benefit of eating algae.

Snails

By Oregon Department of Fish & Wildlife [CC BY-SA 2.0]
By Oregon Department of Fish & Wildlife [CC BY-SA 2.0]
Snails are very small invertebrates that do well in smaller tanks. There are several varieties including the mystery snail and the nerite snail.  They are scavengers that will eat any leftover food scraps and algae.

5 Gallon Stocking Ideas

  • (1) betta
  • (1) betta
  • (2-3) snails
  • (1) betta
  • (3-4) shrimp
  • (1) goldfish

2.5 Gallon Stocking Ideas

  • (1) betta
  • (1) betta
  • (1) snail
  • (5) shrimp