Temporal variations of length, weight and condition of the Asian stinging catfish Heteropneustes fossilis (Bloch, 1794) in the Ganges river (NW Bangladesh)

The present study revealed on temporal variations of length, weight and condition of Heteropneustes fossilis (Bloch, 1794) in the Ganges River, Northwestern Bangladesh. Total 1161 individuals of H. fossilis were caught by various habitual fishing gears such as seine net, cast net and gill net during January to December 2019. For every specimen, body weight (BW) was taken by digital balance to the accuracy of 0.01 g and total length (TL) was taken using a measuring board. Relative condition factor (KR) was assessed by KR = W/(a×Lb), where W is the BW in g, L is the TL in cm and a and b are length-weight relationships parameters. The value of KR ~ 1 specifies good health, >1 specifies over bodyweight as compared to length, whereas <1 suggests a fish in poor condition. The TL varied from 8.5-28.7 cm whereas the BW was 37.17–2250 g. The overall KR for H. fossilis was 0.99-1.06 in the Ganges River. The highest KR was observed in May while the lowest was in January. The KR was significantly correlated with BW in the Ganges River. The outcomes of the study will be helpful for future management of this fish in the Ganges river ecosystem as well as adjacent water bodies. Res. Agric., Livest. Fish.8(2): 259-266, August 2021

​Early Weaning of Asian Stinging Catfish, Heteropneustes fossilis (Bloch) Larvae

Background: Heteropneustes fossilis commonly known as stinging catfish is a popular indigenous fish of the Indian sub-continent. The species has a high consumer demand because of its tender flesh, low fat and high iron content, and is recommended for anaemic patients. Although the species has high consumer preference and potential for commercial aquaculture but, high mortality of larvae and difficulties in accepting compound diet during larviculture are some of the major bottlenecks. Keeping this in mind, the present study was designed to determine the earliest age at which stinging catfish can be weaned to an artificial diet. The information generated from the present study would be very helpful in improving survival during larval rearing. Methods: The larvae were randomly distributed @ 60 larvae/ tank in 21 circular FRP tanks containing 30 L water each and the feeding experiment started at 2 dph. Seven different feeding strategies depending on the type of food (zooplankton, Artemia nauplii, or microdiet) and the age at which those food items were provided to larvae, were evaluated. Result: The results indicated that larvae survival in the groups weaned after 5 days post hatch (dph) was similar to that of those fed solely with Artemia nauplii and zooplankton, although growth of larvae in the weaned groups was less. As larval growth can be compensated at later stages of the rearing process, therefore, larval survival is considered as one of the most important parameters for evaluating the weaning success. Based on the present findings, it is suggested to rear stinging catfish larvae with zooplankton without dependence upon costly Artemia nauplii, and larvae may be weaned to artificial diet after 5 dph. The findings would be very helpful for improving larval rearing of this indigenous catfish species in Indian rural areas.