In the natural environment all waste in the form of organic compounds will eventually be broken down into gases and elements.

The organisms most suited to the existing conditions break down waste and still maintain a healthy aquarium.

Algae are photosynthetic plants which convert energy from sunlight and use inorganic compounds to grow new cells ( single and multi cell forms ) and in turn become a food supply for protozoa, rotifers and crustaceans.

Bacteria and Algae are the prime food source for Protozoa, Protozoa are single celled animals and can easily be observed under a magnification of 100x

Rotifers are multi-cellular animals with flexible bodies and cillia near their mouth.

Small fish feed on protozoa, rotifers, crustaceans, and larger bacteria and algae.
Bigger fish feed on the smaller fish and they in turn are caught and eaten by man.
Man and animals discharge wastes back into the stream where bacteria metabolise the organic matter and the cycle starts over again.