Aquarium can be broadly grouped into three categories, indigenous, exotic and marine.
Different sets of guidelines are required for each category. Generally, indigenous fishes are the hardiest and so easy to keep. Exotic fish requires a fairly constant temperature between 26-28 Degree C. A submersible heater (thermostat) may be required to maintain the temperature during winter months. But, as such as fish is a poikilothermic animal, which adapts body temperature to the changing environment. But sudden changes in temperature many create a problem and stress related diseases are anticipated. With few exceptions, both indigenous and exotics can be kept in the same community aquarium providing all fishes are selected on the basis of compatible size and behaviour. Finally, marine aquariums, by far offer the greatest diversity and the brightest colors of all three categories. Unfortunately, at least in the initial steps of aquarium preparation, they require the maximum time and effort. The guidelines are not difficult to follow. However, one considering a marine aquarium for the first time should contact an expert in this field.