EFFECT OF ILLUMINATION ON GROWTH AND BEHAVIOR OF TWO CARP FISH SPECIES (CARASSIUS GIBELIO AND C. CARASSIUS).

Light is one of the most important environmental factors that influence many physiological, biochemical and behavioral reactions of aquatic organisms. In this work, experiments were conducted to study how illumination influences on the growth of juveniles of two carp fish species (Carassius gibelio and Carassius carassius). In this work, experiments. The experiments were carried out in aquariums and trays with a light gradient. Twenty-twenty five fish were placed in each aquarium, three-four individuals were placed in trays. Fish were fed to saturation three times a day. Optimal types of illumination were identified for the growth of both species. 200-930 lx is optimal for juvenile Carassius gibelio. 230-500 lx is optimal for juvenile Carassius carassius. High illumination and total darkness negatively influenced the growth of both species. Very high illumination considerably slowed the growth rate. Survival in all cases was at 100%. Motor activity of juvenile Carassius gibelio in light-gradient conditions was higher than in balancing illumination. The number of vector movements, the average distance of movement and the total path of fish in the light gradient exceed the corresponding values in control in balancing illumination. When there was no food, the elected zones of the juvenile Carassius gibelio were shifted toward higher illumination. When the food was absent for half an hour, the juveniles chose a zone with the illumination of 600 lux (total time of stay was 15.8 minutes for 1 h). When it was absent for two hours, the juveniles chose a zone with the illumination of 1000 lux (17.3 minutes), and when it was absent for 24 hours, juveniles chose a zone with the illumination of 1000-1200 lux (28.5 minutes). The study discusses the effect of light on growth, the behavior of two species of fish. [ABSTRACT FROM AUTHOR]