Instructions
Research fish compatibility issues thoroughly before you visit the pet store. You should put tropical fish in a heated tank, and tank mates must have similar environmental requirements. Never choose fish simply because you like the look of them. Some of the most attractive fish are also the most aggressive, and if you house them in an inappropriate tank, they may eat or bully other fish.
Search the Internet for a virtual community tank builder. An interactive tank creator allows you to input the size of your aquarium and pick fish from a database. If you overstock the tank or put unsuitable fish together, the program tells you what is wrong. If you are not familiar with species compatibility, this is a useful learning tool, and you can be sure that when you purchase real fish, your community will get along.
Decide what type of aquarium setup you would like. A community tank is a mix of several species that are considered non-aggressive and can co-exist with other fish. A species tank has only one type of fish, sometimes in different color variations. Different species of tropical fish prefer to swim at a particular level in the aquarium. For example, catfish and loaches are bottom feeders; tetras, guppies and platies stay at mid level, and killifish, hatchet fish and gouramis swim near to the surface. Pick fish that live at different levels so that your aquarium always looks interesting and busy.
Look carefully at the quality of pet store fish before you make a purchase, and never buy a fish that looks unwell or lethargic. White spots, torn fins and fluffy deposits are signs of disease, and if one fish in the pet store looks sick, it is likely that its tank mates are infected as well.
How to Pick Fish for Heated Tanks
Compatibility is the most important factor to consider when choosing fish for a heated tank. A new aquarium setup must be completely cycled before adding fish so that ammonia, nitrite and nitrate levels are within acceptable ranges to sustain a fish community. The term "cycled" is used to describe the nitrogen cycle, and new tanks take up to three months to become completely stable. During this time, do not add more than one or two new fish each week. Gradual fish introduction allows beneficial filter bacteria to grow and neutralize excess fish waste efficiently without producing harmful toxins.