Desempenho de alevinos masculinizados de tilápia do nilo (oreochromis niloticus) produzidos em duas estações do ano em tanques de diferentes cores

Abstract

The constructive aspects, especially the colors, can be put to better use in tilapia culture, when there is knowledge on the thermal comfort provided to the bodies. The aim of this study was to evaluate the thermal effect of color in concrete tanks on the performance of Nile tilapia fingerlings in two seasons: rainy and dry. The study was conducted at the Research Center for Aquaculture Rodolpho von lhering, located in the city of Pentecoste, Ceará. The specimens were stocked at 2.4 post- larvae L-1 in 18 concrete tanks of 500L for 28 days during the rainy and dry seasons. The design was completely randomized with six treatments (control, white, black, blue, yellow, green) and three replications. Temperature, dissolved oxygen, pH, total ammonia and nitrite were monitored and conducted quantitative and qualitative phytoplankton analysis. Two mini-stations and meteorological data loggers were used to record the data of temperature and relative humidity. Survival was determined, the final biometrics (final weight and mean length) body gain in weight and length. The final values for weight and length, respectively, were between 0.493 to 0.710 g and 3.047 to 3.633 cm in dry and 0.947 to 1.573 g and 3.273 to 4.533 cm in the rainy season. In dry season, the black color had higher survival (90.6 %) compared with the blue color (75.2 %), which resulted in a lower percentage. In rainy season, survival was less than dry season for all treatments, with the highest percentage in yellow (67.9%), compared with blue color (43.1%), which coincides with the season , had the lowest value. There was no significant difference in weight gain and length between treatments in the rainy season and during the dry (p>0.05), while between seasons significant difference (p<0.05), however the bland and yellow colors in the rainy season showed better results. It is suggested to avoid the use of blue color, to promote survival in the two lower stations. The use of color in concrete tanks proved to be important for optimizing management techniques, despite no significant difference in the mean water temperature in the schedules series of reviews and the presence of potentially toxic phytoplankton blooms.