Fright reaction in Gymnocharacinus bergi (Pisces, Characidae), a relic fish from Patagonia

LOZADA, M.; S. ORTUBAY; V. CUSSAC

ENVIRONMENTAL BIOLOGY OF FISHES

Springer

Año: 2000 vol. 58 p. 227 - 232

0378-1909

Fright reaction, mediated by pheromones, is an antipredatory mechanism in the scale-less ‘mojarra’ Gymnocharacinus bergi (Pisces, Characidae). The aim of this study was to characterise and quantify the fright reaction of this species and to analyse the alarm response to different doses of alarm substance. The alarm response consisted in a general decrease in the swimming speed and a tendency to remain at the bottom of the test aquarium. A threshold effect was induced by a very low dose of alarm substance, and the intensity of the fright reaction was positively correlated to the dose concentration. The main characteristics of the alarm response appear to be consistent with G. bergi’s environmental conditions such as: a higher predation risk in the upper stratum, the abundant pond-weeds of the stream and the great flow and fast speed of the clear waters.(Pisces, Characidae). The aim of this study was to characterise and quantify the fright reaction of this species and to analyse the alarm response to different doses of alarm substance. The alarm response consisted in a general decrease in the swimming speed and a tendency to remain at the bottom of the test aquarium. A threshold effect was induced by a very low dose of alarm substance, and the intensity of the fright reaction was positively correlated to the dose concentration. The main characteristics of the alarm response appear to be consistent with G. bergi’s environmental conditions such as: a higher predation risk in the upper stratum, the abundant pond-weeds of the stream and the great flow and fast speed of the clear waters.G. bergi’s environmental conditions such as: a higher predation risk in the upper stratum, the abundant pond-weeds of the stream and the great flow and fast speed of the clear waters.