Instructions
Check the size of your aquarium. A good rule of thumb is stock your tank with no more than one inch of fish per gallon of water. So, if you have a 20 gallon tank, the combined length of the fish you buy should be no more than 20 inches.
Ask the staff at the pet store to recommend fish suitable to your level of experience. If you are a beginner, the pet store owner might point you to hardy species like zebra danios, gouramis and bettas. If you have more experience, more delicate species like discus, puffer fish and angelfish might be your choice.
Check the descriptions accompanying each species of fish in the pet store. Many pet stores label the tanks with a description of the fish, including its adult size and its temperament. If you are building a community tank, look for fish that are labeled as peaceful. These fish generally can be combined in the same tank with no problems.
Consider stocking your aquarium with schooling fish. Schooling fish like danios, guppies and tetras are fascinating to watch as they move through the aquarium together. These schooling fish also give the tank a more natural look and feel.
How to Choose Tropical Freshwater Fish
Keeping tropical fish can be a fascinating and very rewarding hobby, and it is important to choose the right fish. Choosing tropical fish species that get along well with each other is the best assurance that the tank you create will be a peaceful and relaxing one. It is also important to choose fish that are suitable for your level of aquarium experience--some species of fish are notoriously difficult to keep in captivity, while others are suitable for beginning hobbyists.