When setting up an aquarium the most important factor in determining which fish you can keep is the size of the tank. This list will help in choosing the best fish for a small tank. This discussion will concentrate on tanks up to 10 gallons in size. There are many different types of tanks that are 10 gallons or smaller and many fish that you can keep in these small aquariums.
As a general rule freshwater tropical fish require between 12-20 square inches of surface area to thrive. This can be augmented to a degree by adding air stones and filters to increase surface turbulence and increase the oxygen exchange between air and water. One of the worst things that an aquarist can do to negatively impact the health of their aquarium is to overstock. This will in all likelihood lead to a deteriorating environment that stresses and eventually kills some of your fish. There is a link to a fish stock calculator at the bottom of this page.
With these facts in mind here is my list of some of the best fish to keep in a small aquarium.
1. Small Tetras
Tetras are available in many varieties that are suitable for a small aquarium. They are best kept in schools of varying size based on the capacity of your aquarium rather than keeping single individuals. Tetras are generally peaceful fish and will benefit from a well planted tank as they like hiding places. Some nice choices of tetras for a small tank include the Neon tetra, Cardinal tetra, Lemon tetra, Ruby tetra and the Black tetra. A small school of these fish make for great aquarium viewing and are relatively easy to maintain. Shown below is the Ruby tetra.
2. Small Live Bearers
Small live bearers are another fine choice for a small aquarium. These fish tend to generate more waste than egg laying fish such as tetras, so you should slightly reduce the number of fish that you calculate your aquarium can handle. You may also find that you soon have some baby fish to care for and this will further reduce the capacity of your tank. Having a pair of small live bearing fish and then watching their babies grow is one of the most rewarding aspects of the aquarium hobby, so leave some room for your fish’s offspring. Live bearers that will do well in small tanks are the guppies and platies. Varying colors and varieties are available and you can surely find some that you would like to own. Here are some guppies.
3. Betta Fish
The betta is one of the most popular fish kept in small aquariums. There are many different types of small tanks that are sold specifically to house these beautiful fish. Long flowing fins of the males and the intense colors brought about by selective breeding make these fish a striking example of the beauty of the aquatic world. They are fairly tolerant of changing water conditions and are easy to feed. Keep only one male per tank as two males will fight. It is fine to keep a male and female betta together and they will do well with some small tetras or Cory cats.
4. Cory Catfish
Cory catfish are a wonderful addition to any size tank. The small size of most adults make them especially suitable for small aquariums. They are fun watch as they scour the tank’s substrate while they perform the important task of keeping it clean by searching for food particles that have reached the bottom. They are best kept in groups of at least three and should not be kept singly as they will not thrive alone. Corys are peaceful fish that can get along with all other tank mates. The combination of personality and utility makes these an indispensable choice for your small aquarium and I would strongly suggest that you consider adding them to your tank. Some species that are particularly good for a small tank are the Peppered Cory and the Banded Cory. Some Banded Cory cats are shown here.
5. White Cloud Mountain Minnow
These small, hardy fish are a good choice for a small aquarium. They do well in small schools and are extremely tolerant of varying water conditions and temperatures. White clouds are peaceful and will do well with other small fish such as tetras.
6. Dwarf Gouramis
These peaceful, shy fish reach a maximum size of two inches and are suitable for a 10 gallon aquarium. They are very colorful and pairs will swim together throughout the tank. Dwarf Gouramis require very clean water so be prepared to do regular water changes to maintain these fish. They also will do much better in a tank with live plants including some that float on the surface.
7. Small Barbs
Small barbs are another option for your small aquarium. WhIle some barb species can get quite large, others reach a maximum length less than two inches. Prime examples are the Cherry Barb and the Checkerboard Barb. They are schooling fish that will do better in groups of 5 or more. Keeping a smaller number of individuals may lead to aggressiveness between the barbs. In general they are peaceful and are good tank mates for other small fish. Here is the Checkerboard Barb.
Best Fish For A Small Tank
I hope that this list helps you choose the correct fish for your small aquarium. Take care to follow the stocking guidelines to avoid overcrowding. Many people start with small aquariums and then move on to much larger ones while in some cases space considerations will dictate that a small aquarium is right for you. Please leave any comments regarding this list and share it with your fish keeping friends. Good luck with your small aquarium!