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The near-threatened Ailia coila, commonly referred to as Gangetic ailia, is a catfish species in the Ailiidae family that is indigenous to Bangladesh, Pakistan, Nepal, and India. This study describes the comprehensive explanation of life-history traits of Ailia coila, including length-frequency distribution (LFD), growth pattern (length-weight relationships, LWRs and length-length relationship, LLR), form factor (a3.0), condition factors (allometric, KA; Fulton’s, KF; relative, KR and relative weight, WR), size at first sexual maturity (Lm), optimum catchable length (Lopt) and natural mortality (Mw) from the Tetulia River in southern Bangladesh. Additionally, Lα, a3.0, Lm, Mw and Lopt from various water bodies worldwide using the existing literature were calculated in this study. A total of 316 samples were randomly collected occasionally using traditional gear for a year from July 2021 to June 2022. With an accuracy of 0.01 cm and 0.01 g, each fish’s total length (TL), standard length (SL), and body weight (BW) were measured. The group from 10.00 to 10.99 cm TL was numerically leading and the b values of LWRs indicate positive allometric growth. The a3.0 was 0.005 and KF was the best for assessing the well-being of A. coila. Additionally, WR indicates that the habitat was imbalanced with higher predators. The calculated Lm, Lopt and Mw were 9.19 (~ 9.2 cm TL), 10.7 cm TL and 1.37 year−1 for A. coila in the Tetulia River, respectively. These insights are vital for future research and recommending suitable management strategies for A. coila in the Tetulia River and neighboring basins.

Globally, the quality and high cost of fish feed are vital issues for the development of sustainable aquaculture and food security. Present study was investigated in 4 treatments to find out the compatible species combination for polyculture using Asian watergrass as natural feed for fish in the tidally flooded coastal wetlands for a period of 6 months. Grass carp, common carp, tilapia, mrigal and silver barb were stocked in different species combination with an identical density of 12500 fish ha-1. In all treatments, grass carp and common carp were commonly stocked but other 3 species were disparate to stock among the treatments. Important water quality parameters were monitored those were suitable and acceptable range for aquaculture. The survival of fishes varied from 66.7±8.3 to 91.2±2.9% irrespective of fish species. The total fish production was found significantly higher (p<0.05), 5579.04±238.74 kg ha-1 in T3 followed by 4582.21±200.01 kg ha-1 in T2, 4571.52±189.78 kg ha-1 in T4 and 4448.37±247.26 kg ha-1 in T1 respectively. The results demonstrate that the combination of grass carp, common carp, tilapia, and silver barb in T3 was ideal compatible species for polyculture in coastal wetlands. This technique should be applied in haor, baor, beel, canals, and other water-logged areas pervaded by climate changes. [ABSTRACT FROM AUTHOR]

Utilising novel ingredients in aquafeeds is necessary for the continued expansion and intensification of aquaculture production. Microalgae are utilised widely in aquaculture for a variety of purposes; as live feed for fish and shellfish larvae and juveniles, for the production of algae‐based meals and oils to replace marine derived raw materials in aquafeeds, and for the production of astaxanthin, the carotenoid that gives salmon flesh its characteristic reddish colour. Notably, long‐chain polyunsaturated fatty acids, amino acids, proteins, fibres, antioxidant pigments, vitamins and minerals are among the compounds in microalgae with great biological value. A growing collection of experimental data has demonstrated that these substances are crucial for increasing larval survival and enhancing the growth and well‐being of fish and shellfish. In this review, the processing of microalgae utilised as aquafeed ingredient, the health promoting compounds in microalgae and their role in growth, immunity and disease resistance of fish and shellfish are described and discussed. Simultaneously, major hurdles in the commercial use of microalgae in aquafeed, and future research and development perspectives are all critically discussed. [ABSTRACT FROM AUTHOR]

The near threatened gangetic scissortail rasbora, Rasbora rasbora (Hamilton, 1822), is an economically important, and nutritionally valuable freshwater food fish in south Asian countries. The present study provides the first inclusive explanation on life-history traits of R. rasbora in the Payra River, southern Bangladesh. This species invites research interest due to its nutritional demand and IUCN red list status. Sampling was carried out using different traditional fishing gears during July to December 2019. For each individual, total length (TL) and standard length (SL) were measured to the nearest 0.01 cm using digital slide caliper, while body weight (BW) was taken by an electronic balance with 0.01 g accuracy. A total of 215 specimens were measured ranging from 2.6-12.5 cm TL and 0.22-10.65 g BW during this study. The 4.00 to 4.99 cm TL was numerically leading group of the total population. The allometric coefficient (b) of the length-weight relationships (LWRs) indicates negative allometric growth pattern (b<3.00) for R. rasbora in the Payra River. The results also indicate that the LWRs were highly significant (p<0.001) with r2 values >0.963. In addition, The LLR (SL vs. TL) was highly significant (p<0.0001) with a coefficient of determination values of 0.988. The estimated form factor (a3.0) was 0.007 indicating this fish is elongated in body shape and the size at first sexual maturity (Lm) for combined sexes of R. rasbora was calculated as 7.96 (~8.00) cm TL in the Payra River. The allometric condition factor (KA) varied from 0.0063 to 0.0570 and Fulton's condition factor (KF) varied from 0.3933 to 4.1844. However, KF tended to be lower after 9.0 cm for combined sexes, which may indicate the start of sexual maturation and therefore Lm could be around 8.0 cm TL for R. rasbora. The knowledge about the biological aspects of gangetic scissortail rasbora may be used for improved management tools in the future. [ABSTRACT FROM AUTHOR]

Abstract: The gobioid fish Apocryptes bato (Hamilton, 1822) is a species of mudskipper found in Bangladesh, India, and Myanmar. The reproductive biology of A. bato including sex ratio, size at sexual maturity, breeding season, fecundity, and condition factor was studied in the Payra River, southern Bangladesh during May 2016 to April 2017. A total of 1,028 specimens (303 males and 725 females) were collected. The overall sex ratio was significantly different from the expected value of 1:1 (male: female = 1:2.39, χ2 = 173.23, p < 0.05). Size at sexual maturity was estimated as 4.9 cm standard length. Monthly variations in gonadosomatic index indicate that the main breeding season is from May to December. There was a significant positive correlation of body length and body weight with fecundity. Fulton's condition factor varied in both sexes and was attributed to variations in GSI with maturity. Breeding season was significantly associated with rainfall, but not air temperature. Our findings should improve management and conservation of this fish in the Payra River and surrounding ecosystems. [ABSTRACT FROM AUTHOR]

Biometric indices provide crucial information on fish population growth and aquatic habitat well-being. This study offers the first comprehensive elucidation on biometric indices of Gagata cenia (Hamilton, 1822) specifically; population structure, growth pattern and parameters, form factor ( a 3.0 ), conditions factors, prey-predator status, reproduction, optimum catchable length ( L opt ), mortality and exploitation rate in the Jamuna River, northern Bangladesh. The aim of this study is to estimate stock status of G. cenia in order to protect the declining wild stock. Total of 725 fishes were randomly collected (ranges between 2.7 and 8.5 cm total length (TL), while 0.30-8.24 g body weight (BW)) occasionally using conventional fishing gears during June 2020 to May 2021. The b value of length-weight relationship (TL vs. BW) was 3.33 which indicated positive allometric growth pattern with r 2 value 0.942. Growth parameters were supposed as asymptotic length ( L ∞ ) = 9.09 cm, ( K ) = 0.94 year -1 , growth performance index ( Ø' ) = 1.89 and longevity ( t max ) = 3.2 year -1 for this population. The calculated a 3.0 was 0.0172 and Fulton's condition ( K F ) is the best suited tool for assessing the well-being of this population. Additionally, relative weight ( W R ) specifies an imbalanced territory with regard to the occurrence of predators. The size at sexual maturity ( L m ) and L opt for combined sexes of G. cenia were 5.4 cm and 6.0 cm, respectively henceforth fish sizes 6.0-6.5 cm TL are recommended for exploitation. The current study verified fishing mortality was significantly lower than natural mortality and the exploitation rate ( E ) was 0.32 which indicated the stock was under fishing. Our findings would be very beneficial in planning the sustainable and appropriate management of this fish in Bangladesh and nearby ecosystems., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s).)