Proximate analyses of broodstock and grow-out feeds for gamitana (Colossoma macropomum) and paco (Piaractus brachypomus) and their constituent feedstuffs were conducted. Literature values for specific nutrients known to affect fish reproduction were calculated from published sources for the broodstock diet. Broodstock eggs have not yet been obtained for proximate analysis. However, similar anal...

Measurement of blood parameters has been used for many years as a tool for monitoring the health of fish. The present study investigated the effects of a natural infestation of Dolops carvalhoi Lemos de Castro, 1949, on red blood cells, thrombocytes and white blood cell counts, as well as plasma glucose and serum electrolyte levels in hybrid tambacu (Piaractus mesopotamicus x Colossoma macropom...

We investigated the occurrence and ultrastructurally characterized electrondense nuclear material (nuage) released from the nucleus during oogenesis and early spermatogenesis of Piaractus mesopotamicus, a fish from Pantanal Matogrossense (Brazil) having a seasonal reproductive cycle. The female germ cells presented two instances of nuclear material extrusion: in the oogonia and in the oocyte in...

This paper describes various aspects of oogenesis in Piaractus mesopotamicus (pacu), particularly the changes in nuclear morphology and the nuclear-cytoplasmic interactions during the early developmental stages of oocytes. Material produced in the nucleus and passed to the cytoplasm, known as “nuage”, was observed in oogonia and in oocytes. In the oocyte cytoplasm, this material gives rise to g...

Flavobacterium columnare is the causative agent of columnaris disease in freshwater fish, implicated in skin and gill disease, often causing high mortality. The aim of this study was the isolation and characterization of Flavobacterium columnare in tropical fish in Brazil. Piracanjuba (Brycon orbignyanus), pacu (Piaractus mesopotamicus), tambaqui (Colossoma macropomum) and cascudo (Hypostomus p...