Algae-eating animals help to keep the algae in a garden pond under control without the aid of chemicals. Animals whose diet consist partly or predominately of algae include a variety of fish species, amphibian larvae and numerous invertebrates. Some of these animals will arrive in a pond by themselves, especially in wildlife ponds, but gardeners can speed the process up by adding others.
Common algae eaters for a pond include catfish such as the common pleco and various species of minnows. Before purchasing algae-eating fish, check their requirements, including temperature. Fish sold as algae eaters for aquariums often need specific conditions not provided in a garden pond. Fish species native to your area are the best choice, because they are adapted to the climate, but check that they are suited to small, still bodies of water. The fry -- babies -- of many fish also eat algae.
Some species of pond snail guzzle algae. The species is important when introducing snails, because certain types of snail decimate aquatic plants and multiply rapidly if there are no predators. Species suitable for algae control in garden ponds in the United States include some members of the family Ampullariidae or apple snails. Snails will arrive in a pond naturally, and letting this happen may be the safest course. Suppliers sometimes don't know exactly which species they are selling or their diets.
Frog, toad and newt tadpoles consume algae when they are small. The best way to add tadpoles to a pond is to collect some frog spawn from another pond and let it hatch. The tadpoles may well return to the pond to breed once they have changed into frogs. Adding tadpoles would have the same effect. In this case however, the tadpoles may not deal with the algae problem that year because, after they reach a certain size, they become carnivores. Gardeners should not buy tadpoles, or frog spawn, from a supplier unless the supplier it is certain the tadpoles belong to a native species. Introducing exotic amphibians into the ecosystem can cause serious problems for local wildlife.
Various other small invertebrates, including shrimp larvae, daphnia or water fleas and copepods, consume algae. Most of these arrive in a pond naturally, provided it doesn't contain too many chemicals. Some of these creatures are carried on the feet of water birds; others are the larvae of terrestrial insects such as mosquitoes. To get a natural balance quickly, a gardener can add a bucket of water from an established pond.