Sex Differentiation and Gonadal Development of striped snakehead (<i>Channa striata</i> Bloch, 1793)

Abstract

The striped snakehead Channa striata is a predatory fish whose life cycle still holds many mysteries. One of the obstacles to cultivating this fish is the difficulty of obtaining male broodstock. This study aimed to examine the sexual development of C. striata. Such information will be of benefit not only for the cultivation of C. striata, but also for sustainable management and exploitation of wild populations. Samples were collected from June to September 2017 in the inland waters (rivers and canals) of Barru and Bantaeng Districts, South Sulawesi, Indonesia. Gonads were observed both macroscopically and microscopically including gonad morphology, acetocarmine solution staining, and histology. We found that female C. striata were larger and more numerous compared to males in the same population (2 female:1 male). We identified five different oogenesis phases in C. striata: immature, maturing, mature, spawning (partial spawning), and post-spawning (spent). Some individuals of standard length 81-229 mm had an intersex (ovotestis) type gonad. In fish of standard length 110-241 mm, two types of gonads were found: a pair of ovaries suspected to be undergoing apoptosis, and a pair of developing testes. Two pairs of gonads were also found in an adult of length 381 mm, but both pairs were ovaries, of which one was in mature stage (ripe), the other undergoing apoptosis. This study suggests that Channa striata is at least potentially hermaphroditic, and its gonads can undergo a differentiation phase. We recommend further study on the genetic mechanisms and/or environmental influences which determine gonad development and sex differentiation in C. striata.