Determining the appropriate time and hormone administration for induced spawning and egg production of the shoemaker spinefoot rabbitfish, Siganus sutor (Valenciennes, 1835) during the reproductive season

Abstract

This study was conducted to determine the appropriate time and hormone administration protocol for induced spawning of the shoemaker spinefoot rabbitfish, Siganus sutor. Four different hormone administration treatments including LHRHa2 hormone at dosages of 10 and 20 μg/kg body weight (BW) (treatments L1 and L2), HCG hormone alone at a dosage of 2000 IU/kg BW (treatment H) and combined with 5 mg metoclopramide/kg BW (treatment HM) plus the control, 1 ml 0.9% saline water (treatment C) were administered on eight dates in mid-2016 (April 12, May 1, 8, 15 and 22 and June 1, 8 and 15). Females (470.14 ± 8.56 g BW) received the hormone injection twice over a 24-h interval and all males received HCG hormone at a dosage of 2000 IU/kg BW; hence, each fish was used just once for the injection of hormone. A significantly greater number of spawned fish (70.8 ± 16%) was observed in treatment L2 compared with the other treatments (L1: 16.7 ± 10.8%; H: 45.8 ± 14%; HM: 45.8 ± 14%; and C: 4.2 ± 0.2%). Significantly greater numbers of eggs per female (469,083 ± 70,453 eggs) were obtained in treatment L2 compared with the other treatments (L1: 103375 ± 48,872 eggs; H: 294500 ± 74,348 eggs; HM: 287458 ± 72,856 eggs; and C: 18542 ± 18,000 eggs). Cluster analysis showed that the best time for induced spawning of S. sutor was 15 to 22 May and the best hormone for induced spawning was LHRHa2 at a dosage of 20 μg/kg BW of females. Such information can be helpful in the management of breeding programs for this important fish species.