Water Quality (more to come later)

The other main water quality issue is the buildup of ammonia and nitrates from fish waste. Ammonia is the end product of the protein you feed your fish. It is very toxic to fish. If you filtration system is working (see Filtration) it should quickly convert ammonia to nitrate via the action of friendly bacteria. Nitrate, not as harmful as ammonia, is still harmful if the level gets high. Guppies can get rotten fins, not grow large, or become susceptible to parasites. Nitrate is a compound plants use to grow so one way to reduce it in your aquarium is to have some aquarium plants. Show guppy breeders commonly use Java Moss since it is easy to manage and grows in even low light levels. Other plants include foxtail (a floating rootless plant) and water sprite (floating with dangling roots).

Using plants alone to remove nitrate is not generally good enough to produce large show guppies. The most common method in addition to plants is to do water changes. This means replacing a fraction of your water on a regular basis. Common routines would be 10-15% twice a week although some breeders have automatic drip systems with slow constant replacement. How you set up water changes depends on you skill with plumbing or your tolerance to do frequent manual changes. Of course, lowering the density of your fish per gallon will also reduce nitrate contamination.