This Trichomycterid catfish, Plectrochilus sanguinus, was observed on the Napo River in Loreto, Peru. This group of catfish is infamous for the alleged habit of swimming up the urethra of humans that are urinating in the rivers of South America. While there is one medically documented case in the Brazilian Amazon, it is unlikely that the phenomenon happens with regularity. Trichomycterid catfishes are parasitic on larger fish. They swim into the gill chambers and chew on the gill tissue, drinking the blood of the larger fish. In fact, candiru are almost exclusively blood feeders (haematophagous).