Effect of hormonal treatment on artificial propagation, spawning performance and embryonic development of striped snakehead Channa striata (Bloch, 1793).

Present study describes the spawning induction of striped Snakehead, Channa striata using carp pituitary extract (CPE) and LH-RH agonist i.e. Buserelin (Glp-His-Trp-Ser-Tyr-Ser-tBu-Leu-Arg-Pro-NHEt). Total four treatments were designed under both hormones trail and treated as control group, T1, T2, and T3 with three replications of each treatment. While breeders under all hormone treatments showed spawning performances, no spawning performance was observed in control group. Latency time after hormonal treatment was lowest (20-24 hrs) in case of CPE than Buserelin (25-30 hrs). Regarding to CPE, spawning, fertilization and hatching rate were higher with the increasing doses of CPE in different treatments. The highest mean ± Standard deviation spawning, fertilization and hatching rate were 85.60±8.58 %, 79.38±4.89 % and 64.33±6.60 % respectively in T3 where dose of CPE was 80 mg kg-1. Similarly, in case of Buserelin hormone highest spawning rate was found in T3 (80.61±5.59) where dose of Buserelin was 0.80 µg kg-1 body weight. Fertilization rate was on the level 48.57±5.99, 70.62±5.33 and 90.32±4.79 respectively for T1, T2, and T3.Whilst, hatching rate was found 20.81±4.91, 37.11±4.50 and 61.33±6.61 in T1, T2, and T3 treatments respectively. However, T3 exhibited best performance regarding spawning, fertilization and hatching rate which were significantly higher than other two treatments.The current study revealed that spawning induction using carp pituitary extract and Buserelin is effective and might be useful for artificial breeding of Channa striata. Regarding to dose application i.e. 80 mg kg-1 of CPE and 0.80 µg kg-1 of Buserelin may be successfully applied to ovulation stimulation of Channa striata.

Temporal distribution of plankton and fish species at Mithamoin Haor: Abundance, composition, biomass and ecosystem based management approach.

Wetlands are the major climatically vulnerable habitat globally. In Bangladesh, Haors are the representative of wetland habitat that plays a significant role in ecology, economy, and social structure. In the present study, physicochemical and biological properties and their interaction at Mithamoin haor of Kishoreganj district of Bangladesh were depicted based on the samples collected from July 2020 to June 202. In total, 46 genera representing 4 different groups of phytoplankton were identified comprising the highest percentages of Chlorophyceae (44.52 %). Zooplankton was represented with 13 genera which was dominated by rotifer. During the study, 56 fish species of 7 orders were documented and the dominance was showed by Cypriniformes (46.84 %). Fish biomass was highest during January and the lowest during May. Planktivores were represented the predominant (55.32 %) group in the haor. Water temperature, transparency, pH and water depth were considered as the major environmental factors influencing the phytoplankton, zooplankton and fish biomass of the haor. Although some fish and plankton species have declined over time, the overall diversity of fish and plankton in the Mithamoin haor was relatively stable. Multiple strategies, including an ecologically oriented framework, might be useful for conserving the prevailing fishery resources of this wetland in future.

The first report on a new Tor species, Tor barakae Arunkumar & Basudha 2003, from Bangladesh using DNA barcoding technique.

Mahseer are large-scale fish of the Cyprinidae family that inhabit South and Southeast Asian mountainous streams, rivers, and reservoirs. Tor tor and Tor putitora, two species of the Tor genus, were reportedly found in Bangladesh. This study aimed to confirm the species level of specimens collected from the Sangu River. The collected samples were identified using the DNA barcoding technique, followed by amplifying 645 bp of the cytochrome oxidase c subunit 1 gene (COI) using the FishF1/FishR1 universal primer. The sequence similarity was conducted using BOLD and NCBI databases which showed 99.85-100 % similarity to the reference genome. The genetic divergence between T. putitora vs. SRI, BT, and ST was found to be 0.0239, 0.0239, and 0.0238, respectively. The genetic divergence between T. tor vs. SRI, BT, and ST was 0.0272, 0.0272, and 0.0270, respectively. In the phylogenetic tree, two clusters were formed where collected specimens (SRI, BT, and ST) formed a subcluster with the reference genome (NC_056296.1 T. barakae) with 100 % bootstrap support. This study's findings revealed the presence of a new Tor species named Tor barakae in the Sangu River basin in Bangladesh.