Photo credit: Claudia Turra (Uruguay) –  Description: Claudia Turra and Abdel Rahman El Gamal

In nature, the black catfish, Rhamdia quelen reproduce during most of the year except during the winter months. Being fractional spawners, females release small amounts of eggs several times during the spawning season. The absolute fecundity (number of eggs/female) could range from about 25,000 – 40,000 eggs/female/season of non-sticking demersal eggs of 1.1 – 2.8 mm diameter.

Although the species spawns naturally in ponds, induced spawning has good results. Induced spawning is achieved with the injections of carp pituitary extract or with human chorionic gonadotropin (HCG).

After spawning and fertilization, fertilized eggs are incubated as shown in one of the photos.   A second photo shows the embryonic development during incubation while the yolk sac larvae is shown in the third photo. The incubation period depends on water temperature (48 hours at 22°C ; 27 to 36 hours at 24° C after fertilization).

In three or four days, larval yolk sacs are absorbed and exogenous feeding starts whereas artemia nauplii are often provided for 3-4 days before feeding on artificial feed. The cannibalism during the larval phase is prevented by keeping larvae in the dark for an appropriate period. Ten days after hatching, the larvae weigh about 100 mg.

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