ANÁLISE DO DESENVOLVIMENTO GONADAL DE MATRINXÃ, Brycon amazonicus (GUNTHER, 1869) EM DOIS AMBIENTES DE CULTIVO.

With the stabilization of mining and fishing, fish farming stands as an alternative to contribute to the fish supply. So every year, the production of fish from fish farming has increased considerably. In Amazonas, the matrinxã, Brycon amazonicus, has been widely used for fish farming due to its favorable characteristics for cultivation. However, captivity breeding still has some problems that hinder the constant supply and in sufficient quantities to meet the demand of fish farmers. Among the reasons that may contribute to the failure of the spread of this species is referred to the lack of knowledge about their reproductive biology and including the understanding of the maturity of gonads process. The objective of this study was to characterize the gonads of the matrinxã farmed in two different systems in their morphological and histological aspects in order to establish equivalence between the macroscopic and microscopic characteristics and relate them to the size and / or age. Fish were sampled from two farming systems (earthen ponds and dam). Samples were collected monthly between June and November 2014, the gonads were classified through a macroscopic scale and histological slides were prepared and stained with hematoxylin eosin. The fish raised in the earthen ponds were significantly smaller in length and weight when compared to the dam. For the analysis of the gonadosomatic index (GSI), it was observed that the ovaries were more developed in the months of October and November and testicles in October in farmed fish. GSI of females kept in the dam was higher in November indicating greater development in fish with 12 months of age. The macroscopic characteristics of the fish ovaries collected both in the earthen ponds and in the dam were classified as immature and maturing, but when observed oocyte development were all early maturing. In males we observed three maturation stages in fish from the pond, immature, early maturing and intermediate maturity, while in the dam, just immature individuals were found.Keywords: fish farming, Brycon amazonicus, gonadal development, gonadosomatic index.