Aquaculture Research

Not AvailableThe 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 (R2 = 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

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Present Status and Future Scope of Freshwater Aquaculture Sector in India

 Aquaculture is being the fastest food production sector in the world with an estimated production of about 179 million tonnes. The fish production from capture fisheries (96 million tonnes) is almost stagnant for many decades but the demand is rising significantly due to the awareness about the health benefits of fish consumption. The additional demand for fish consumption must be achieved only through aquaculture. The current fish production from aquaculture has increased from 44 million tonnes (2005) to 82 million tonnes (2018) and it is sharing almost 45% of total global fish production but this production level is not sufficient to fulfil the demand (FAO, 2020). This article will focus on the present status and future scope of freshwater aquaculture in India to achieve blue revolution in India. </p

Some facts on cannibalism in Wallago attu and its management during captive seed production

 Wallago attu is a bony fish in the Siluridae family and is considered to be a large catfish due to its large size availability in the wild, with fish reaching 45 kg. It is found in tanks, rivers, reservoirs and connected water bodies of the Indian subcontinent, Thailand, Vietnam, Cambodia and Indonesia. It is an excellent food fish due to high nutritional quality and softness of fl esh, and lack of intramuscular spines. The shining silver colour of its body also attracts consumers. This catfi sh is listed as an endangered species, and presently it is only available in the market occasionally, due to the decline of wild populations. Researchers from our institute have attempted captive production but encountered high losses due to cannibalism during its early life, which does not encourage its adoption for aquaculture. Cannibalism due to genetic and behavioural factors may persist throughout or disappear after certain life stage in many fishes, and may be species specific, but W. attu is known to be a highly predatory fi sh. It is necessary to understand the causative factors governing cannibalism in this catfish. However, cannibalism can be initiated by rapid transfer from live to commercial feed, size differences during stocking, seasonal changes, feeding at long intervals, high density rearing, feed distribution, feeding method and size of feed etc. Many of these factors apply to this catfish as causes of cannibalism. Studies revealed that the management of some of these causes can reduce cannibalism during the seed rearing period for this species. Predatory nature of the catfish W. attu is a mid-feeder in the water column. It may also swim on the surface or bottom of the water while feeding to seek an advantageous position for predation. Adults prefer to eat live fish or aquatic organisms. The fry are also predacious, showing cannibalistic tendencies. Certain morphological and anatomical adaptations favour its voracious predatory feeding Wild caught Wallago attu. </p

Recent Advances in Carp Culture in India

 Culture of the three IMC (catla, rohu and mrigal) and three exotic major carps (silver carp, grass carp and common carp) have been the main stay of aquaculture in India contributing a share of more than 70% of the inland production over the years. Although introduction of the exotic carps into the carp polyculture system during early sixties added new dimension due to their high growth rates and compatibility with our major carps, the low consumer preference has been the major bottleneck for their large-scale adoption. Although the standard recommended practice in the country involves polyculture of three Indian major carps or combination of three Indian major carps and three exotic carps, adoption has, with several modifications, largely dependent on prevailing market demand and resource availability in different regions. Though scientific farming on a national basis at farmers’ level has shown production of 3-5 tons/ha/year, carp production levels of 8-10 tons/ha has been a common occurrence in commercial farms. </p

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