Plants decompose, fish create liquid and solid waste and uneaten food will eventually rot. Fish waste comes in the form of ammonia, which, oddly, kills fish. In the wild, natural elements like rain, wind and a steady natural water flow remove these elements from the water. But in an aquarium, changing the water and filtration should work to remove most aquarium waste.
Replacement removes some waste and dilutes the rest.
Automatic water changers can be purchased to complete this task, although hand-changing the water can easily suffice. Fish will enjoy replacement water if it's a little cooler, though extreme temperature changes are harmful. Filtration Install a filter before putting anything else in the aquarium. Here are a few common types of filters. Mechanical filters Mechanical filters are cylindrical-shaped, and can be either internal or external.