Living systems of aquatic plants and animals for exhibition, scientific analysis or decoration, aquariums are balanced when aquatic plants and animals exist in respiratory cooperation. Fish exhale carbon dioxide and eliminate wastes which the plants absorb as fertilizer. Plants use the carbon dioxide and emit oxygen during photosynthesis which the fish inhale. Cooperation exists in this sense. Sufficient daylight, uniform water temperature and prepared fish foods are all that are needed to support most freshwater fish. A large variety of aquatic plants is good for aquariums.

Fish convert approximately 85 percent of what they eat into protein food as contrasted with approximately 10 percent converted by beef cattle.

There are two types of pond construction the dug pond formed by digging a sunken shape out of the earth, and the levee pond made by natural levees or by mechanically digging out a level pond bottom. Levee ponds allow for drainage naturally since they are higher than ground level.

When the pond is fully constructed and the clear water allowed to stand for a week or two, it is time for fish body weight per day; with kitchen wastes, percent of body weight. This formula is designed to produce a 3 percent weight gain per day.