Gammarus pulex or scud as they also known, is a native freshwater crustacean. Despite its common name, the freshwater shrimp it's actually a species of amphipod. They are found in rivers, lakes, small streams and ponds. They are detritus feeders and eat dead plants, dead insects, dead fish, algae and other organic matter. They can also be fed fishfood, algae wafers or sinking pellets. They can be kept in both coldwater and tropical aquariums as well as ponds and make an excellent addition to a wildlife pond They are a great natural food source for fish and are also a great source of calcium for amphibians. They're excellent at eating all types of algae especially hair algae they love the stuff!