Mating behavior of aquarium-held freshwater catfish Pseudobagrus nudiceps (Bagridae), was observed. Some 22-23 h following human chorionic gonadotropin injection, males patrolled the nest area, while females maintained a stationary midwater position (pre-mating behavior). Mating began with a female visiting a male's nest, successive stages including male 'embracing' of the female, female stirring of eggs and female departure. Duration of the 'embrace' was 24.4-26.0 s, mating behavior sequences being repeated 10-18 times with intervals. Spawning was performed in the male's nest. The number of eggs, measuring 1.4-2.2 mm in diameter, laid by a single female was estimated at more than 1000. At 22.5°C, the eggs started to hatch 65.0-69.5 h after fertilization. After spawning, the male stayed near the eggs.
The paper is entirely in Japanese (except for the English abstract), but a picture is worth a thousand words, so:
