Histological changes of gonads in the white spotted rabbit fish (Siganus sutor) under photoperiod fluctuations

Authors

1 Department of Fisheries, Faculty of Agriculture and Natural Resources, Science and Research Branch, Islamic Azad University, P.O.Box:775-14515, Tehran, Iran

2 Iranian Fisheries Research Organization (IFRO), P.O.Box: 14155-6116, Tehran, Iran

Abstract

In this study, the effects of photoperiod alternation on the maturational progress of the white spotted rabbit fish (Siganus sutor) were investigated. A hundred adult fish (total length: 306.4 ± 2.12 mm; body weight 401.5 ± 8.45 g) were caught from Lavan Island. They were divided in 300 l tanks (n = 5) and exposed to tree different day length including 8, 12 and 16 h combined with constant 2000 lux light intensity with three replicates during prespawning season. After 60 days, the GSI mean values were 2.03± 0.34%, 5.83± 0% and 10.39± 0.80%, respectively, for females and 8.15± 0.43%, 13.91± 1.52% and 14.56± 0.41%, respectively, for males according to photoperiods. These results showed significant differences between fishes were reared under 8 h and 16 h photoperiods (P<0/05). In the case of gonad histology, the maturity stages of ovaries along with photoperiod increasing were 3, 4 and 5; whereas testes of males reared in all treatments reached to stage 5. These results clear that increasing of light duration from 8 h to 16 h in combination with 2000 lux light intensity have positive relation with the gonadal progress of  white spotted rabbit fish in both sexes. Thus, rearing of fish fewer than 16 h day length obtains the highest level of sexual maturity.   

Keywords

Journal of Animal Environment
Volume 6, Issue 4 - Serial Number 4
March 2015
Pages 231-240

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