Q. I have bought many freshwater angelfish, and every last one of them has died. I have checked the water and everything else I can think of and I still do not know what to do. What do these fish need in order to live?
A. You ask a complicated question, which, if answered completely, would be large enough to fill a book. In fact, through the years there have been several books written on this very subject, and you may wish to check with your local pet dealer or library to see if one is available.
Angelfish, Pterophyllum scalare, are medium-sized cichlids from the tropical forests of the upper Amazon region in South America. They live in weedy, brushy backwaters with little flow or current. Although most fish in the hobby are tank bred and have been acclimated to a wide variety of water conditions, the wild species come from soft acid water. It is my opinion that tank-bred fish do better under these conditions as well.
Hard, alkaline water seems to stress angelfish and make them easy victims to many diseases. Good, clean water that is efficiently filtered by a power filter, but without turbulent outflow, is the best environment. Angels seem sensitive to a build-up of nitrogenous waste materials and to heavy metals or medications. Frequent, partial water changes, especially those done with the use of a "gravel vacuum," help immensely in preventing these problems.
If the angelfish are to be kept in a community aquarium, it should be at least 30 gallons in capacity, although a larger tank is even better. Angelfish prefer a planted tank with peaceful, slow-moving species for tankmates. Good examples of peaceful tankmates would be pencilfish, large neon tetras, harlequin rasboras, hatchetfish, dwarf gouramis, Corydoras catfish and Otocinclus catfish. This selection would give color and motion in all sections of a tank but not bother the angelfish. Stay away from barbs, aggressive tetras, such as the silver-tip tetra or the black-line tetra, and the various forms of plecostomus. They will harass the angels to a point where they will probably die.
If the angels are to be kept in a single-species tank (or a breeding tank), nothing smaller than a 20-gallon show tank should be used. The unusually deep body proportions of angelfish require sufficient tank depth if the fish is to be at its best. I normally keep young angels in a community setup to grow them to full size and then switch them to a single-species tank for breeding. Temperatures in my community tanks usually range from 72 to 76 degrees Fahrenheit, but these are raised to 80 degrees Fahrenheit in the breeding tank.
Angels are easy to feed and will accept most foods offered, including commercially prepared dry foods. A varied diet is the only real secret to keeping angels healthy and happy. Too much of any one food and the fish may decide that this is the only one they want to eat. If this happens, and it frequently does, the fish do not get all of the required nutrients and they tend to sicken and die.
Angelfish can be a pleasing focal point for any aquarium and are well worth keeping. They just require a little attention to detail and good aquarium techniques.