Introducing Marine Aquarium Fish
Initially, fish are introduced exactly as with freshwater fish. In an established tank, newcomers will probably be attacked, so feed your old fish well and shift some of the coral around. The previous occupants will be so busy squabbling with each other over establishing new territories that they will ignore the newcomers.
Seawater has much less capacity to hold dissolved oxygen than does freshwater, so proportionately fewer fish can be kept in given size of tank. Just how many fish can be kept in one aquarium? The traditional formulas — so many centimeters of aquarium liter of water do not work, because individual fish have different tolerances for crowding. On average, each medium-sized fish needs probably 5 to 6 liters (1.1-1.3gal) of water in a properly kept aquarium. This will not allow much scope for survival if any-
Thing goes wrong, however. In addition, you must consider the lifestyle of the fish. Generally, small territorial fish like Dascyllus can tolerate some overcrowding, as can inactive fish like Groupers. Fast-swimming fish, however, need more space, as do nervous, highly strung fish like Butterfly fish and Surgeonfish. It is only common sense to study each fish carefully in the dealer’s tank, and to find out as much as possible about it before committing yourself to buying it. Always get the dealer to demonstrate that the fish is feeding properly before you purchase, especially with tempera-mental fish like Butterfly fish.