These small flukes are found in the intestinal tract of numerous mammals. There are large anterior and ventral suckers. The testes are symmetrical, large, and are in the hindbody. The cercarial stage that comes from the snail has a stylet and a short tail. The cercariae penetrate the skin of the fish and the larval stages are found in the tissues of the fish. The final host becomes infected by the ingestion of the fish host.

One member of this family, Nanophyetussalmincola is of additional importance in veterinary medicine because it has been shown to be the vector of the agent causing salmon poisoning in dogs on the west coast of the United States. It does not appear that the cat plays any major role in this story, but it is possible for a cat to develop patent infections if it is fed infected fish. The details of the biology and treatment of this infectious rickettsial agent can be found in many of the textbooks on microbiology and infectious disease, and these details have not been presented here.