Resumo

PENA-MENDOZA, B; GOMEZ-MARQUEZ, J.L; SALGADO-UGARTE, I.H  e  RAMIREZ-NOGUERA, D. Reproductive biology of Oreochromis niloticus (Perciformes: Cichlidae) at Emiliano Zapata dam, Morelos, Mexico. Rev. biol. trop [online]. 2005, vol.53, n.3-4, pp.515-522. ISSN 0034-7744.

The reproductive season of tilapia was studied by monthly samplings at Emiliano Zapata dam, Morelos State, Mexico. From February 1999 through February 2000 a sample of 50 fish was taken from the commercial catch (castnet, 6.5 cm of mesh size). The observed sex ratio was 1:1.29 (females:males) (²=10.26; p<0.05). The tilapia reached maturity at 151.3 mm (females) and 152.0 mm (males) of total length. Rainy (August) and dry (February) seasons were determined as the breeding period. Fecundity variation was better correlated with length (r=0.7473; p<0.002) than with weight (r=0.7395; p<0.002). The fecundity ranged between 243 and 847 oocytes per fish, with egg diameter from 300 to 3 700 µm. Intensive breeding activity in August and February coincide with phytoplankton biomass increase. Rev. Biol. Trop. 53(3-4): 515-522. Epub 2005 Oct 3.

Palavras-chave : Reproduction; Oreochromis niloticus; gonadosomatic index; hepatosomatic index; fecundity.