The overriding influence on the behavior of any creature (with people as notable but not complete exceptions) is the need to survive. Biologists are examining the phenomenon of play — that is, behaviors engaged in seemingly for enjoyment alone, among birds and mammals, but our fish and invertebrate friends seem to have a definite reason for everything that they do.

These reasons, or motivations, for behavior, generally exist to assist the animal in finding a suitable environment, obtaining food, avoiding predators, and reproducing. Armed with this knowledge, the wise aquarium keeper will analyze what is observed in the aquarium and will use what is learned to better care for his or her pets. Of course, many fish, will, of necessity, modify their behaviors in captivity. In some cases, the adjustments will be so drastic that the actual purpose or function of what the fish are doing will be lost on us. However, as you gain experience, you will generally be able to see the relation that the captive behavior has to its natural counterpart.

It is, as always, very important that we know as much as we can about the natural histories of the fish that we keep in captivity. Knowing, for example, whether a particular species is an active hunter or a sessile ambush predator will enable us not only to provide adequate care but also to recognize problems when they arise.