Today, an estimated 1 in 7 Americans keeps some form of exotic fish in his glass tanks, and breeders are struggling to keep up with the constant demand for new and different aquarium species.
Freshwater tropical fish are generally hardy, and will live for several years if you take a few precautions. Professional fish farmers and breeders have found that the healthiest habitat for their livestock is not a sterile environment, but one in which a correct biological system is set up to maintain life. In a home aquarium, that means:
* Allow some zooplankton (algae) and oxygen-using bacteria to accumulate to avoid the toxic ammonia buildup that eventually comes with the production of unfiltered fish wastes. The bacteria convert the waste to nitrogen compounds and the algae use the nitrogen for plant growth. Hobbyists who constantly change the aquarium water to eliminate the ammonia compounds end up stressing their fish by changing their environment. Keep at least one glass panel for algae buildup, or allow it to accumulate on rocks, wood, or other habitat.
* Give your aquarium a good three to four weeks to start functioning as a miniature ecosystem before you load it to capacity with fish - although you will want to begin with a few fish to get the cycle started.
* Don't overload with inhabitants. A good rule of thumb is one inch of fish for each gallon of water. Overloading causes stress.
* Select compatible fish, not just those that catch your fancy. A good retail aquarium store employee, or a resource guide, should be able to tell you which species are good ''community'' fish and which aren't. Some species are predacious; others are timid.
* If there's any question about how much your fish have been fed, then feed them less. Overfeeding allows uneaten food to deteriorate, creating unnecessary wastes and unwanted bacteria. If any food is still at the surface after 15 minutes, remove it and feed less the next time. (If you are leaving the house for several days, you should even go without feeding rather than trying to overfeed all at once.)
* If you suspect you have a diseased fish for any reason - unusual behavior or blemishes on its body - then remove it to an ''isolation tank.''
* Provide a light to simulate a photo-period if your tank is in a dark area of a room.