Catfishes: Siluriformes

Physical characteristics: Candirus are 1 inch (2.5 centimeters) long. The body is naked and eel-like. There are spines on the gill covers, the mouth is suckerlike, and the lower jaw is toothless. Candirus are yellowish or almost clear.

Geographic range: Candirus live in South America.

Habitat: Candirus live in freshwater. They burrow in sandy bottoms.

When a fish opens its gill cover to expel water, the candiru enters, lodges itself using its spines, bites off the tips of the host's gill filaments, gorges itself with flowing blood, and then drops off of the fish. The entire process takes 30 to 145 seconds. (Illustration by Bruce Worden. Reproduced by permission.)

Diet: Candirus eat the blood of other fishes.

Behavior and reproduction: When a fish opens its gill cover to expel water, the candiru enters, lodges itself using its spines, bites off the tips of the host's gill filaments, gorges itself with flowing blood, and drops off to the bottom. The entire process takes 30 to 145 seconds. Scientists are not sure how candirus reproduce.

Candirus and people: Candirus can swim up the urinary tracts of people.

Conservation status: Candirus are not threatened or endangered. ∎