Seasonal changes in hepatosomatic index, gonadosomatic index and plasma estradiol‐17β level in captively reared female rabbit fish ( Siganus guttatus )

Abstract

The seasonal changes in hepatosomatic index (HSI), gonadosomatic index (GSI) and plasma estradiol‐17β (E2) level in female rabbit fish (Siganus guttatus) were investigated. The relationship between plasma E2 levels with these indices and ovarian growth was also evaluated. Each month, at least 10 female broodfish were sacrificed to collect liver, ovary and blood for HSI, GSI and plasma E2, respectively. GSI and HSI were calculated as percentage (%) of relative weight of gonad and liver to total body weight, respectively. Plasma E2 level was measured using enzyme‐linked immunosorbent assay method (ELISA). Ovaries were cut and stained for histological observation. The results included seasonal changes in plasma E2 levels, stages of ovarian development, GSI and HSI. The highest level of E2 was observed in June (1,445.62 pg/ml) and during vitellogenesis (2,305 pg/ml). GSI and HSI values significant fluctuated monthly. The highest HSI and GSI were 1.72% in May and 3.58% in June, respectively. The pattern of plasma E2 levels showed a relationship with GSI and different stages of ovarian development. HSI was associated with ovarian stages. During vitellogenesis, the highest value (1.9%) of HSI was observed. Histological sections showed that rabbit fish is a multiple spawner. These results contribute to further understanding of female rabbit fish reproductive biology in captivity. Important reproductive parameters such as HSI, GSI and E2 can be used to indicate maturation status of this fish species.

Feminization of Maroon Clownfish (<I>Amphiprion biaculeatus<I/>, Bloch 1790) with 17β-Estradiol Hormonal Induction

“…This is in line with the research by Harlıoğlu et al (2018) which stated that compared to controls, the GSI and HSI values in female crayfish injected with E2 had increased. According to Nunes et al (2011), Pham and Nguyen (2019), and Kumar et al (2022), the highest HSI values in Sardina pilchardus, Siganus guttatus, and Planiliza parsia were found in the vitellogenesis phase. Thus, the fish in this study were in the vitellogenesis process after hormonal injection.…”

“…Both are regulated by the hormone estradiol. According to Pham et al (2012) and Pham and Nguyen. (2019), estradiol levels in plasma correlate with GSI, HIS, and ovary development in the fish.…”

Seasonal changes of plasma sex steroids in captive longtooth grouper Epinephelus bruneus (Bloch) in subtropical regions

“…In this study, the seasonal changes of sex steroid levels (E2 in female and 11-KT in male) in LG were examined in a subtropical region (Figure 1). It is well known that the plasma levels of sex steroids (E2 and/or 11-KT) annually fluctuate with maturity in many species, such as the rabbit fish Siganus guttatus (Pham & Nguyen, 2019), rainbow trout Oncorhynchus mykiss (Espinosa et al, 2013), red-spotted grouper E. akaara (Li et al, 2007), chub Leuciscus cephalus L. (Guerriero, 2007), tench Tinca tinca (Pinillos et al, 2003), Arctic charr Salvelinus alpinus (Tveiten et al, 1998), red grouper E. morio (Johnson et al, 1998), and bambooleaf Psudolabrus japonicus (Morita et al, 1997).…”

New insights into the recent collapse of Eastern Baltic cod from historical data on stock health

“…HSI in fish exhibits an annual cycle associated with reproduction [ 44 ]. For EBC, this cycle cannot easily be accounted for by incorporating quarter effects on HSI, as the timing of peak spawning has changed over the years [ 45 ].…”