Pantanal parasitic catfish (Paravandellia oxyptera)

Biology

Found to exhibit parasitic traits. Inhabits rivers with sandy to muddy bottom. Forages both during the day and at night seeks the gill chambers of larger fishes, especially catfishes. Enters and leaves the gill chamber during the host's ventilating movements: feeds on blood drawn from the gill filaments and may stay in the gill chamber for 1-3 min; when gorged with blood, moves to the bottom and buries itself in the sand. A single large catfish tethered on the river bank may feed thousand of these parasitic catfish over a period of up to 6 hours. Two females, 1.8 cm TL, caught in January (wet season) had about 150 mature oocytes each, and one male 2.0 cm TL had well-developed testes. Large numbers of this fish may kill fishes tethered by fishermen.

Source: FishBase, licensed CC BY-NC 4.0.