Étude éthologique de la relation mâle-femelle au cours du cycle de reproduction chez Hoplosternum littorale

Résumé En

Hoplosternum littorale, an armoured catfish (Callichthyidae), lives in tropical stagnant waters of French Guiana. Its breeding season begins with the rains, and is characterized by the building of a floating nest. The fishes studied were captured in a marsh (at Kaw) and brought to the laboratory where they were weighted and paired. Each pair was then placed in a tank (100 x 50 x 50 cm) provided with a shelter and aquatic vegetation. Fifty six pairs were observed for fifteen minutes, six times a day, at regular time intervals. Red light was used during the night. The reproductive cycles lasted for 4 to 6 days. Four main stages were distinguished : 1) Pair formation and initiation of nest building. Five activities are characteristic : (a) male and female parallel swim, (b) face to face, (c) male stimulation by the female, (d) vertical swim towards the water surface, and beginning of the surface bubble production. 2) Nest building. Wriggling swim at the bottom of the tank and plant carrying (by male only), circling swim under the nest (by male and female). The female actively stimulates the male during the building of the nest. She displays a typical pseudo-oviposition posture at the bottom of the tank. 3) Egg laying and fertilisation. The following sequence was observed : stimulation of the male by the female ; milt oral collection by the female, followed by immobilisation and dropping towards the bottom of the tank ; vertical swim to the nest and milt transfer to the bubble layer ; egg laying. The sequence is then repeated. Egg laying bouts are interrupted by short rest periods. 4) Care of the eggs. The male becomes aggressive after egg laying and can chase, pursue, and threaten the female. He alone takes care of the nest, keeping it afloat by depositing more air bubbles. When the male is not aggressive towards the female, both assume the maintenance of the nest. In both instances, the male vigorously attacks every object moving towards the nest (by jumping out of the water with fins erected), displaying a patrol type behaviour after these attacks. The behaviour of H. littorale is compared to that of other fishes. Bubble nest building is observed not only among Callichthyids but also among many Anabantids, a family unrelated to armoured catfishes. However, all these fishes live in poorly oxygenated waters.