Introduction to Tropical Fish
Tropical Fish, any small fish that can be kept successfully in a warm-water aquarium. Most such fish are native to tropical regions. However, some fish that can be found in cooler water in the wild state have been developed by selective breeding into domestic varieties that thrive best in warm-water aquariums. In aquariums, tropical fish live an average of two to three years. A few survive for 10 years or more.
Tropical fish are valued for their delicate or brilliant colors, attractive or unusual shapes, lively and graceful movement, and interesting habits. Most tropical fish range in length from one to five inches (2.5 to 12.5 cm). In the United States, keeping and breeding tropical fish in home aquariums began in the late 1920's and became a popular hobby after World War II. In many countries, including the United States, there are organizations and publications devoted exclusively to the hobby.
Most aquarists (keepers of aquariums) prefer freshwater fish, because it is more difficult to provide saltwater varieties with a suitable environment. Also, saltwater fish are more expensive, because it is harder to collect and ship them. More than 1,500 varieties of freshwater tropical fish have been successfully kept in home aquariums; of these, about 500 varieties are usually available commercially. Goldfish are the most popular aquarium fish, but some experts do not consider them to be tropical because they do not need particularly warm water.
Keeping Freshwater Tropical Fish
The AquariumOne of the most important requirements for keeping fish healthy and attractive is clean water in sufficient quantities to provide them with adequate amounts of oxygen and freedom of movement. An aquarium should be rectangular in shape. A goldfish bowl does not allow for enough water surface for adequate absorption of oxygen and release of carbon dioxide and other gases poisonous to fish.
Oxygen consumption varies greatly according to the age, size, and species of fish. However, a good general rule for an aquarium not equipped with an aerator is that there should be one gallon of water and 24 square inches of water surface for each inch of fish exclusive of tail. (In metric units, this is 1.5 liters of water and 60 cm2 of water surface for each centimeter of fish.) When an aerator is used, about half as much water volume and surface is needed. If the aquarium is properly cared for, the water need never be changed.
The aquarium should be placed out of direct sunlight during most of the day to prevent the growth of algae, which are harmful to freshwater tropical fish. It should not stand in a draft or near a room heater. Suitable water temperatures for most tropical fish range from 70° F. to 80° F. (21° to 27° C.). The fish should never be subjected to sudden changes of temperature.
Aquarists who breed fish usually have a second tank for spawning and keeping the young, because adult fish often eat the young, even their own. Peaceable fish of the same approximate size can be grouped together. Aggressive kinds must be kept alone or with their own species.
FeedingA variety of feed can be bought in pet shops. Dry prepared feed consisting of a combination of fish and shellfish meal, beef meal, and plant material is excellent. In addition, fish should be given such live feed as daphnia, brine shrimp, white worms, tubifex worms, and certain water protozoans. Animal and vegetable material prepared by freeze-drying (drying frozen material in a vacuum) may sometimes be substituted for live food. Chopped fish, liver, and earthworms are good fish feed. Fish do not overeat, but they should not be given more feed than they can eat in 15 or 20 minutes, because uneaten particles decay and stimulate the growth of harmful bacteria.
Preventing and Curing DiseaseFungus diseases and white spot (or ich), caused by protozoans, are the most common diseases affecting tropical fish. Treatment usually consists of adding chemicals to the aquarium water. Afflicted freshwater fish often benefit from being placed in a weak saltwater solution for several hours. Diseases can often be prevented if newly acquired fish are placed in a tank filled with a solution of potassium permanganate for a few hours before being put in with the other fish.
Kinds of Freshwater Tropical Fish
LivebearersFavorites with aquarists who breed fish are the livebearers, whose eggs are hatched in the female's body. Guppies, perhaps the best-known, are noted for their brilliant colors. Mollies, platys, and swordtails are also popular.
Egg-layersAmong the many egg-laying families of fish with members suitable to home aquariums are cyprinids (or cyprins), characins, labyrinth fish, and cichlids. Especially popular cyprinids include barbs, danios, and rasboras. Characins include tetras, pencilfish, and piranhas. .)
Labyrinth fish and cichlids are especially popular with aquarists because of their interesting habits and their beauty. Labyrinth fish get oxygen from the air as well as from the water, and drown if held under water too long. Most species make nests of bubbles on the water. As the female spawns, the male takes the eggs in his mouth, places one in each bubble, and guards them until they hatch. Popular labyrinth fish are gouramis, Siamese fighting fish, paradise fish, and climbing perch.
Cichlids include several species known as mouthbreeders. After the eggs are spawned, one of the parents (usually the female) takes them into its mouth and holds them, not eating anything until they hatch some two weeks later. The jewel fish and the butterfly cichlid are especially beautiful cichlids.
Marine Tropical Fish
A difficulty in keeping marine fish is providing them with seawater. Some aquarists have had success using preparations that are added to soft tap water or to distilled water to make synthetic seawater. Marine tropical fish need more water and water surface than do freshwater tropical fish. Marine aquariums are constructed in much the same way as freshwater aquariums. However, because seawater reacts with the chemicals contained in metals, paints, and cements, only all-glass tanks or tanks with frames made of stainless steel of a certain kind can be safely used. Any other materials that may come in contact with the water must be covered with water proof epoxy paints or with plastics.
Marine tropical fish can be fed approximately the same kind of feed suitable to freshwater varieties, except that they need larger proportions of live or freeze-dried animal feed, such as brine shrimp. Little is known about diseases of marine fish, but the preventive measures used with freshwater tropical fish have proved successful. Some diseases of marine tropical fish have responded to combinations of antibiotics.
Among marine fish suitable for home aquariums are angelfish, butterfly fish, dam-selfish, parrot fish, triggerfish, and sea horses.
Livebearers make up the family Poeciliidae. The guppy is Poecilia reticulata. Mollies are of the genus Mollienesia; platys and swordtails, of the genus Xiphophorus.
Cyprinids make up the family Cyprinidae. Genera of barbs include Puntius, Capoeta, and Barbodes; of danios, Danio and Brachydanio. Rasboras make up the genus Rasbora.
Characins make up the family Characidae. Genera of tetras include Hyphessobrycon, Hemigrammus, and Cheirodon; of pencilfish, Nannostomus and Poecilobrycon; of piranhas, Pygocentrus.
Labyrinth fish make up many different families. Genera of gouramis include Helostoma of the family Helostomatidae, and Colisa and Trichogaster of the family Belontiidae. The Siamese fighting fish is Betta splendens of the family Anabantidae; the paradisefish is Macropodus opercularis of the family Belontiidae; the climbing fish is Anabas testudineus of the family Anabantidae.
Cichlids make up the family Cichlidae. The jewel fish is Hemichromis bimaculatus; the butterfly cichlid, Apistogramma ramirezi.
Angelfish are of the families Pomacanthidae and Cichlidae; butterfly fish, Chaetodontidae; damselfish, Pomacentridae; parrot fish, Scaridae; trigger-fish, Balistidae; sea horses, Syngnathidae.