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

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.

Automated summary

The Asian catfish, Clarias magur, is an endangered fish species highly valued for commercial purposes in India and other South-East Asian countries. A study on induced spawning showed that medium-sized female broodstock of 130-180g had significant effects on reproductive performance, egg, and larval quality.