Correlations of oocyte diameter with some morphometric characters in the nile tilapia, Oreochromis niloticus L.

Abstract

A study was conducted to determine the correlation of oocyte diameter with some morphometric characters in a Philippine strain of Oreochromis niloticus L. One hundred and thirty-five 7- to 9-month old sexually mature female broodstock (body weight: 71±35 g; standard length: 13.1±2.1 cm) were randomly sampled from a pool of broodstock maintained in 4 m2 net enclosures suspended in an earthen pond. The following morphometric characters were determined for each fish: body weight, standard length, genital pore dimension, and genital papilla dimension. Intra-ovarian oocyte samples were obtained by inserting a soft silicon rubber tubing into the ovipore of the fish and aspirating the oocytes by mouth. There were no significant correlations between the average oocyte diameter and any of the morphological characters studied. Results justify the adoption of an ovarian biopsy technique for assessing the stage of gonadal maturity in sexually mature tilapia.