An analysis of sex stimuli enhancing ovarian growth in pubertal African catfish, Clarias gariepinus

Abstract

Ovarian growth in pubertal African catfish was followed during a 100-day period. Different combinations of male sensory stimuli resulted in three distinct levels of ovarian development. A basic level (ovarian weight 5.3–7.5 g; GSI 1.9–2.7%) was reached in controls (no contact with males) and in females having visual and auditory contact with males. An intermediate level (ovarian weight 11 g; GSI 4%) was reached if olfactory contact with males was possible. A maximum level (ovarian weight nearly 20 g; GSI 7.3%) resulted from unlimited contact between the two sexes. The question is discussed whether the difference between maximum and intermediate levels of ovarian growth should be ascribed to a better water quality due to experimental conditions rather than to the presence of male tactile stimuli. The possible existence of male primer pheromones responsible for the observed stimulation of ovarian growth in pubertal African catfish by enhancing vitellogenesis is also discussed.