Stocking level is based on filtration and water changes. The bigger the filter and the more often the water is changed the more fish you can put per liter. I break my tanks into top level, mid water and bottom feeder. I normally get some top level guys like pancake face, african butterfly fish or in the big tanks Arowana to float at the top. read more
Some fish are capable of withstanding a wide range of temperatures and are usually hardy in just about any region when kept indoors without an aquarium heater. Some, such as the common goldfish, can even be kept outdoors in temperate climates. Non-tropical fish include the clown loach, pufferfish, goldfish, koi and common guppy. read more