Eliciting Natural Behavior in the Aquarium
Once a fish's behavior is studied and understood, you can set about creating a habitat that will allow the fish to thrive and, perhaps, to exhibit a range of its behaviors. An aquarium of appropriate size and furnished in a close approximation of the natural habitat of the fish is the first prerequisite.
The proper temperature, light cycle, pH level, and careful attention to all other environmental parameters are all essential if your fish are to feel at home. For many species, normal behavior will be exhibited only when day length and temperature are alternated in an approximation of a natural cycle. Your fish must also be given the opportunity to engage in their normal behaviors. For example, sticklebacks must be provided upright twigs and properly sized bits of grass and other materials if they are to construct their incredible little nests.
Contrary to popular belief, providing numerous hiding places to shy aquarium fish will not result in their remaining hidden from view. Rather, such will provide a sense of security and they may become quite visible. You will then be able to view a number of interesting behaviors that would not be exhibited were the animals kept in unnatural conditions.
An interesting and easily manipulated facet of fish behavior is the obtaining of food. Providing natural foods whenever possible will result not only in healthier animals but also in your ability to see a number of fascinating activities. Allow your pets to forage whenever possible. This is most easily accomplished with predatory species by introducing food items that will live in the aquarium. In freshwater aquariums, for example, black worms might be allowed to burrow into the substrate, while small hardy food fish such as mummichogs might be introduced into marine aquariums. It is important to allow the food animals to adjust to the aquarium water, just as you would were you introducing a new pet fish, so that they themselves will thrive. This type of feeding technique might best be used as an adjunct to your normal feeding schedule, as it may be difficult to ascertain if your animals are getting enough to eat when live prey is the main source of food.
Putting whole greens into the tanks of herbivorous species or encouraging the growth of algae in such tanks are excellent ways to observe a number of unique feeding behaviors. Another interesting option is to crack a whole clam or mussel and drop it into a community aquarium. You will be quite surprised and amused at the lengths that various fish will go to to obtain this welcome treat.