So, you've found your sea legs as a fishkeeper by setting up and maintaining a coldwater tank. Are you ready to take your hobby to the next step? As an "advanced beginner," you're suitably prepared for the challenge of tropical species.
There are hundreds, if not thousands, of warmwater tropical fish sold as aquarium pets. Most require a constant temperature in the tank of about 78 degrees Fahrenheit, but depending on the kind of fish you choose, the optimum environment may range somewhere between 70 and 84 degrees. You'll need a a good-quality, thermostatically-controlled heater of the correct wattage to maintain water temperature.
As a tropical fishkeeper, you will have a large selection of species to pick from. Among the most popular are members of the tetra family, from the bright red and electric blue neon tetra to the silvery-yellow lemon tetra. Ranging from about one to three inches, tetras are quick movers and like to form schools, so it's a good idea to get four to eight of the same type. These peaceful swimmers are relatively easy to care for and can live up to 10 years.
If housed in a large enough tank, elegant angelfish will grow up to six inches or larger. Members of this species are easily identified by their long, flowing fins and flat, triangle-shaped bodies. Although their original coloring is silver with black stripes, other varieties, including marbled, all-black and pink, are available. If you plan to keep some, please pay attention to size--larger angels have been known to eat their smaller tankmates.
Hardy platys are also good additions to a warmwater community. And if you like dramatic-looking fish, consider the swordtail--but do make sure your aquarium has a secure cover or these champion jumpers may leap out. Note that only the males have long, swordlike tails.
Tropical catfish are good choices, too--and there's lots of variety, from small one-inch species to the larger six-inch kinds. Those from the Corydoras group make a great clean-up crew, as they're bottom feeders that will gobble up any food that ends up on the floor of the tank.
There are many different kinds of barbs--and in general, these fish are best kept in small schools of three or four. Among the most popular are the shy, delicate-looking cherry barb and the black and orange tiger barb. Note that the larger, two- to four-inch varieties may nip at the fins of any slower, long-tailed residents of the tank.
Fast-moving danios are also popular and easy-to-care-for tropical species. Consider the blue and silver zebra danio, who can live up to 5 years, and the four-inch giant danio, who'll appreciate lots of room for swimming.
When selecting fish for your warmwater aquarium, the old rule of thumb of one inch of fish per gallon is a good guide to follow. In a 10-gallon tank, for example, you could keep 10 one-inch fish or 5 two-inch fish. And remember, one of the hardest, most important parts of tropical fishkeeping is selecting species that will do well in the same type of water conditions and will get along with each other. Be sure to ask at your aquarium store and determine your fishes' needs before you buy.