Maternal size on reproductive performance, egg and larval quality in the endangered Asian catfish, Clarias magur

Abstract

The Asian catfish, Clarias magur, is an endangered fish species, which is immensely important due to its high commercial value in India and other South-East Asian countries.Various anthropogenic activities and natural habitat loss have greatly impacted the biodiversity of C. magur in natural water bodies, leading to the addition of this species to the endangered species list. The development of captive spawning and selection of an ideal broodstock size are critical steps to maximize the efficiency and robustness of conservation efforts for the catfish. An induced spawning experiment was conducted to ascertain the reproductive performance, egg and larval quality of catfish broodstock from fish with varying body weights. Five female C. magur broodfish from each of the following size ranges, F65 (65 ± 5.0); F130 (130 ± 7.9), F180 (180 ± 3.5) and F250 (253 ± 9.7g), were selected along with male broodfish with the same body weight range. The present study's results revealed that the stripping response was higher (F = 2.06; p = 0.15) for medium-sized F180 magur female broodstock; however, no significant differences were observed for this group. Total (F = 20.79; p < 0.001) and relative fecundity (F = 3.09; p = 0.057) were found to be significantly higher for F250 and F65 broodfish respectively. Total fecundity had a strong significant positive correlation (r = 0.99; p = 0.012) and also had significant linear regression relation (R 2 = 0.98; p = 0.012) to maternal size. Hatching rate was observed to be significantly higher (F = 7.82; p = 0.002) for the medium-sized broodfish, F130. The medium-sized broodstock of 130-180 g had strong positive influence on the growth and survival of the progeny, while F250 broodfish produced poor-quality larvae, which resulted in reduced larval growth performance and survival. Specific growth rate (SGR) and thermal growth coefficient (TGC) were also found to be significantly higher for F130 female broodstock. Hence, the selection of medium-sized (130-180) or 1-to 2-year-old female broodstock had a significant effect on the reproductive performance, egg and larval quality of magur in captivity. The results from this study can be utilized as helpful and practical information enhancing selection protocols for the hatchery operators to select ideal broodstock based on size, enabling the production of viable egg and larvae in indoor conditions and a scalable seed production system.

Photoperiod manipulation leads to successful voluntary captive spawning of butter catfish Ompok bimaculatus during the non‐spawning breeding season

“…To estimate the hatching rate, fertilized eggs were scooped out after 24 h of spawning and the number of hatchlings released from the eggs was counted. The data obtained from the samples were analysed for GSI, fecundity, fertilization and hatching rate using the following formulae (Ferosekhan et al, 2019, 2021; Tumpa et al, 2020)…”

“…The individual body weight of larvae was measured by digital electronic balance. The length gain, weight gain, specific growth rate (SGR) and larval survival rate were calculated as described by Ferosekhan et al (2019, 2020, 2021) and Raizada et al (2013).…”

“…To estimate the hatching rate, fertilized eggs were scooped out after 24 h of spawning and the number of hatchlings released from the eggs was counted. The data obtained from the samples were analysed for GSI, fecundity, fertilization and hatching rate using the following formulae (Ferosekhan et al, 2019(Ferosekhan et al, , 2021Tumpa et al, 2020)…”

“…Larval survival was significantly higher in the 12L:12D treatment (80%) group than that in the other groups. In the 9L:15 treatment, higher natural mortality was observed, and the eggs may not supply enough nutrients to produce viable offspring (Ferosekhan et al, 2021), which may negatively impact vitellogenesis. This indicates that sperm quality was superior to egg quality in both long and short photoperiods.…”

“…Catfish is gaining importance as an aquaculture candidate due to its flesh quality, nutritional value, therapeutic value, higher consumer preference and high market value (Debnath, 2011; Ferosekhan et al, 2021; Sahoo et al, 2016). Recently, Indian butter catfish, Ompok bimaculatus (commonly known as “Pabda”), has gained popularity due to its favoured taste, superior nutritional profile, smooth bony structure, rich lipoprotein content and consumer preference (Basavaraja et al, 2013; Biswas et al, 2018; Md.…”