Influência de diferentes formatos de tanques na larvicultura de Piracanjuba Brycon orbignyanus

Abstract

Piracanjuba (Brycon orbignyanus) is a native species that has great potential for breeding in captivity. One of the biggest obstacles in the larviculture of this species are the high mortality rates, which makes a low percentage of larvae reach the juvenile and adult stages. Therefore, effective management strategies to assist in the formation of specific protocols that meet the needs of each species are extremely important to seek economic and productive efficiency. The size of the tank in which fish are cultivated in indoors systems can influence cannibalism by favoring or reducing the number of encounters, which is related to agonistic behavior. In addition, it also alters the energy expenditure to stay at different points in the water. This work aims to evaluate the effects of different tank formats on the performance, behavior and survival of piracanjuba larvae. The experiment was conducted at Central Biottery of the Federal University of Lavras. Fifteen aquariums with a density of 25 larvae per liter were used, in a DIC, with 3 treatments and 5 repetitions, started right after hatching. The fish were kept under 12 hours of light and 12 hours of dark photoperiod and were fed with newly hatched brine shrimp nauplii (Bio Artemia), in an average daily amount of 530 nauplii per larva divided into six meals. Three types of maintenance aquariums were used with the same volume of water and the same color, but with different shapes (cylindrical, rectangular and square). The experiment lasted 16 days and was carried out in a static system, with constant aeration and partial water change of 40% of the total volume daily, with aquarium cleaning twice a day, together with temperature measurement. At the end of the experimental period, the parameters of zootechnical performance, survival, cannibalism and behavior were evaluated. The experimental variables (weight, standard length, total length, survival, light-dark anxiety test and aggressiveness test) were subjected to analysis of variance, significant differences were compared by Tukey test (5% probability). All statistical analyzes were performed using Minitab® version 18.1 software. In this study, the different tank formats did not influence the performance and growth of piracanjuba larvae. The square-shaped aquarium showed a higher numerical survival compared to the other treatments, moreover, in the light-dark test it was the treatment in which the fish spent more time on the light side (p=0.019) indicating a lower state of anxiety. Furthermore, a significantly higher mortality was observed at night, indicating that the presence of light or food frequency that occurred during the day may have inhibited cannibalistic behavior in all treatments. Given the above, for this species, the square shape was found interceding the extremes and favored survival, being the most suitable for the cultivation of larvae. However, studies should be continued to identify the influence of this hydrodynamics on a greater number of parameters for fish larviculture in indoor systems.