Development of fingerlings of Piracanjuba (Brycon orbignyannus), Vallencienes (1849) (Teleostei: characidae) in tanks fertilized with organic manures

Abstract

The objective of this paper was to study the development of Piracanjuba (Brycon orbignyanus) in tanks  under differents organic fertilizers. The experiment, entirely randomized, was accomplished in 16 tanks of 1000 liters, fertilized with manures of bovine (BOV), pigs (SUI), chickens (FRG) and others without fertilizer (SAO), using 15 fish/m3 with an initial average weight and length of 10,87+0,31 g e 9,78+0,07 cm. After 30 days, the experiment showed a uniform development of the fish and high survival rate in the studied density. The treatments presented significant statistical differences (P < 0,05) for weight gain and daily growth, except for the treatments BOV and SUI when compared to each other. The temperature and the dissolved oxygen were the abiotic factors that exerced a larger influence on the aquatic biota, affecting the development of the fish. Among the phytoplankton there was a larger presence of nanoplanktonic organisms favoring the development of the zooplankton, mainly the Clorophyta, with the Scenedesmus species, and the Cianophyta, with the Microcystis species, and among the zooplankton, the largest presence was of the rotifera from the species Brachionus and Keratella, followed by the copepods. The treatment fertilized with manure of chickens made possible a larger development of the plankton community, and better results of the development of the fish, demonstrating the importance of natural food in its diet.