OBSERVATIONS ON THE BIOLOGY OF LABEO GONIUS (HAMILTON)

Abstract

Observations on the biology of Labeo gonius (Hamilton) in confined waters
have been made and the data on the different aspects have been analyzed and
discussed.
The length - weight relationship of the species can be expressed by the
equation US'=0.000007153 L 3.0865. The monthly fluctuation in the condition
factor of the adult fish was found to be related to the maturity cycle.
L. gonius matures within a year. The ratio between males and females
was found to be 1:1.052. Macroscopic and microscopic examination of the
gonads, ova diameter measurements and gonadosomatic index indicated that
mature fish become available from March to August, th© peak being in May.
The size frequency of ova in ovaries in different stages of maturity suggested
that the species breeds only ones in a year. The statistical relationships between
fecundity in relation to total length, total weight and ovary weight and ovary
weight in relation to total length have been established.
From an exclusively plankton-feeding habit in the post-larval stage, the
species changes over to a column and bottom-feeding habit in the juvenile stage,
subsisting on vegetable matter, phyto and zooplankton organisms, mud and sand.
The adult fish is predominantly a bottom feeder, the diet consisting of fresh and
decaying plant matter, mud and sand, phytoplankton and filamentous algae.
Preliminary experiments indicated that the growth rate of L. gonius is
poor in comparison to major carps.