Instructions
Change the water in the tank at least once or twice a week. You should replace at least 50 percent of the old water with new, clean water.
Keep the tank temperature more or less constant using a "heater-stat." Heater-stats are inserted into the tank and maintain a specific temperature. Adding new water may briefly alter the overall temperature, but the device will bring it to the static temperature.
Clean the gravel on the bottom of the tank with a gravel vacuum (available at most pet stores and aquarium stores). Clean at least a quarter of the gravel weekly.
Install a filter in your small fish tank if it doesn't already have one. Filters help automatically keep the water clean of waste, toxins and other debris that is harmful to the fish.
Scrub algae growth on the sides of the tank with a stiff aquarium brush.
How to Clean a Small Fish Tank
Fish are relatively easy to maintain and interesting to observe. You can keep goldfish in a simple bowl or build an underwater world with fake rocks, plants and a variety of tropical fish. Regardless of the fish you keep, you need to clean the tank regularly to keep the fish healthy and alive.