The effects of Synthetic gonadotropin releasing hormone analogue (S-GnRHa) on artificial propagation of spotted scat, Scatophagus argus (Linnaeus, 1766)

Abstract

Spotted scat Scatophagus argus is an important brackishwater species predominantly inhabited in south-west coast of Bangladesh. The aim of this study was to develop a hormonal induced reproduction protocol of farm-domesticated S. argus along with larvae rearing techniques. Synthetic gonadotropin releasing hormone analogue (S-GnRHa) was injected at the dose of 60:30 μg/kg BW (Female: Male). In female fish 20% of the total dose was applied as priming dose and 12 hours later 80% as resolving dose. The latency period ranged from 32 to 36 h was determined by observing the time between first injection and ovulation. However, after achieving full oocyte maturation and ovulation, eggs were collected by stripping and fertilization was carried out using pooled sperm from male. The mean ovulation, buoyancy, fertilization and hatching rate were found 70±1.8; 68±7.7; 40±2.3% and 53±5.2% respectively. Over the embryonic development following stages were witnessed in embryos: meroblastic cleavage (2-cell), blastula, gastrula and pharyngula. Maximum embryos hatched within 19 hr post fertilization at 28±2.0°C temperature and 28±2.0 ppt salinity. In this study, we dispense the first information on the reproduction of spotted scat in captive condition using S-GnRHa and the optimal dose limit and larval rearing techniques are established. Further studies are warranted to develop the larvae into juvenile stage under variable environmental conditions to increase the fertilization, hatching rate and survival of embryos.

Optimization of stocking density of Spotted Scat (Scatophagus argus) in brackishwater nursery

“…The effect of stocking density on survival and growth rate of several teleosts juveniles during nursery rearing has been reported in Turbot (Scophthalmus maximus) (Irwin et al 1999), Russian sturgeon (Acipenser gueldenstaedtii) (Celikkale et al 2005), Olive flounder (Paralichthys olivaceus) (Bolasina et al 2006), California flounder (Paralichthys californicus) (Merino et al 2007), Senegalese sole (Solea senegalensi) (Salas-Leiton et al 2008), Dark barbel catfish (Pelteobagrus vachelli) (Zeng et al 2010) and Mahanadi Rita (Rita chrysea) (Ferosekhan et al 2019). Besides natural supply, this species is able to breed in captive conditions (Washim et al 2022). In hatcheries, a high stocking density of larvae can impose stress leading to compromised growth, whereas low stocking density can be uneconomical to produce juveniles.…”

Transcriptomic analysis provides new insights into the secondary follicle growth in spotted scat (Scatophagus argus)

“…It is thus suitable for mixed cultivation with other marine shrimp and fish. Although artificially-induced spawning can be achieved in some laboratories (Cai et al, 2010;Mandal et al, 2021;Washim et al, 2022), the efficiency of artificial propagation is still very low in the actual breeding process, mainly because of the lack of female fish which can produce a large number of healthy and viable eggs. Elucidating the mechanisms underlying oocyte growth may thus help increase the quality and quantity of eggs produced by female S. argus for artificial breeding, thereby promoting its sustainable development in aquaculture.…”