What Do Freshwater Mussels Eat? Diet and Feeding Methods Explained

The freshwater mussel is a common freshwater mollusk and a typical filter feeder. It has no ability to actively chase prey; instead, it relies mainly on the constant beating of cilia on its gills to keep water flowing into its body, from which it filters out tiny food particles. As a result, its feeding process goes on almost all day long.

In the natural environment, freshwater mussels mainly eat planktonic algae in the water, such as diatoms and green algae, and they also feed on zooplankton, protozoa, bacteria, and organic debris from plants and animals. These food particles are suspended in the water body and are extremely small, which makes them perfectly suited to the mussel's filter feeding. Freshwater mussels mostly inhabit the mud and sand at the bottom of ponds, lakes and rivers; the more fertile the water body, the generally more abundant the natural food available for filtering.

In terms of feeding method, the posterior edge of the freshwater mussel's mantle forms an incurrent siphon and an excurrent siphon. Water carrying food particles enters through the incurrent siphon, passes through the gills for filtering and sorting, and the edible particles are sent toward the mouth, while unusable impurities are expelled with the water flow through the excurrent siphon. The intensity of filter feeding is often related to water temperature and water quality, and feeding is more active within the suitable temperature range.

Under artificial breeding conditions, especially when cultivating pearl mussels, water quality is usually improved through fertilization to promote the reproduction of planktonic algae, providing the mussels with sufficient natural food. Soybean milk, rice bran and other finely crushed foods can also be added as a supplement. It should be noted that water that is too lean will leave the mussels short of food and growing slowly, while water that is too fertile can easily cause oxygen deficiency. Therefore, in breeding, the water should be kept at a moderate fertility with sufficient dissolved oxygen, so that the mussels can grow healthily and the pearl cultivation results are better guaranteed.