Genetic information is essential for conservation and future aquaculture development of the endangered catfish Rita rita (Hamilton, 1822). Two hundred catfish, R. rita, 50 from four rivers, the Old Brahmaputra, Jamuna, Meghna and Kangsa were collected and analysed to evaluate the genetic diversity and population structure using five microsatellite primers (Cba06-KUL, Cba08-KUL, Cba09-KUL, Phy03-KUL and Phy07-KUL). Four of the five amplified loci were found polymorphic (P95) in all the populations and 46 alleles were recorded with 9 to 14 alleles per locus. Differences were observed in the total number of alleles ranging from 41 to 44, effective number of alleles from 29.96 to 37.46, observed heterozygosity from 0.57 to 0.76, Shannon’s information index from 2.09 to 2.30 and polymorphic information content from 0.84 to 0.88 among the four populations. Results exposed the highest levels of genetic diversity in the Meghna population while the lowest in the Kangsa population of R. rita. All the populations were significantly deviated (P < 0.001) from the Hardy-Weinberg equilibrium for all the loci. Nei’s genetic distance between populations ranged 0.007 to 0.017 with low overall genetic difference FST = 0.011 and high gene flow Nm = 24.333, indicating that R. rita populations were not subdivided. This study revealed a high level of gene diversity with deficiency in genetic heterogeneity in all the populations of R. rita, emphasising natural management, conservation and rehabilitation measures of this species.

Naturally diseased climbing perch Anabas testudineus was confirmed to be caused by Aeromonas hydrophila bacteria by aeromonas isolation medium (AIM), 0/129 vibriostatic agent and esculin hydrolysis. Such naturally diseased koi fish weretreated with four antibiotics: captor (chlortetracycline hydrochloride BP 45%), renamox 15% -Vet (amoxicillin trihydrate BP), oxy-Dox-F (oxytetracycline 20% and + doxycycline 10%), renaquine 20% -Vet (flumequine) at lower, recommended and higher doses were performed to examine the efficacy of the drugs. Captor was given at doses of 0.8, 1.0 and 1.2 g/3 litres of water separately. Doses of renamox 15% -Vet were given at 0.8, 1.0 and 1.2 g/litre of water. Doses of oxy-Dox-F were 0.8, 1.0 and 1.5 g/Kg body weight and doses of renaquine were 10, 12, and 15 mg/Kg body weight. Among the four antibiotics, effect of captor and renaquine at recommended dose showed the best result where 100% fish were recovered. However, renamox and oxy-Dox-F showed best result at higher dose.

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The current study was assessed the socio-economic patterns and trends of livelihoods of the Old Brahmaputra River fisher's community in the Jamalpur district from July 2021 to June 2022. The livelihood status was analyzed regarding age distribution, family size and composition, religion, marital status, education levels, living standards, diseases, healthcare, electricity, sanitation, drinking water facilities, fishing, and employment status. Most fishermen (45.76%) were 35-50 years old, with 91.53% were Muslim. The average family size for a fisher was medium, with 5-7 members. 33.9% were illiterate, 37.29% could only sign, 20.34% finished primary school, and 8.47% completed SSC. Most fishermen had tin roofs 59.32%, straw roofs 22.03%, semi-paka houses 11.87%, and paka houses 6.78%. Approximately 45.76% of fishers relied on village doctors, 33.9% on the Upazila Health Complex, 8.47% on Kobiraj, and 11.87% on MBBS doctors. Approximately 93.22% of fishermen's homes were equipped with electricity. Fishing was the main activity for more than 57.63% of the fishers. Fishermen have suggested specific management strategies to halt the trend of decreasing fish catches and increasing fish production. These include restricting the use of harmful gear, prohibiting the catching of juvenile fish, creating fish sanctuaries, and releasing fish fry.