Caniru or candirú (also canero, toothpick fish, or willy fish, penis fish) refers to parasitic freshwater catfish of a number of genera in the family Trichomycteridae. They are found in the Amazon River and have a reputation among the natives as the most feared fish in its waters, even over the piranha. They are eel-shaped and translucent, making them almost impossible to see in the water. Some species have been known to grow to a size of 6 inches (~15 cm) in length.