Mytella strigata, a potentially invasive species native to South America, is rapidly spreading across various aquatic ecosystems around the globe, posing a threat to native mussels. This study presents the first comprehensive de novo transcriptome assembly of M. strigata. We generated 254 million reads, which were processed and assembled using the Trinity assembler, resulting in 60362 transcripts with an N50 of 1,578 bp and over 93–98% completeness, as confirmed by BUSCO analysis with multiple ortho-datasets. A number of databases were used for functional annotation, including UniProt, KEGG, Reactome, InterPro, and eggNOG. Gene Ontology and pathway analyses identified transcripts associated with key biological processes, including those associated with cell signalling, metabolism, stress responses, cancer pathways, and immune regulation. This dataset enriches the bivalve database by advancing the understanding of the adaptive success and evolutionary resilience of this invasive species. The present study provides a fundamental framework for future research on the ecological and evolutionary impacts of this invasive species.

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A new species of troglobitic eel loach Pangio juhuae, is described from Kerala, India. Pangio juhuae sp. nov. is distinguished from its subterranean congeners by the presence of a dorsal fin; four pectoral rays and five segmented anal fin rays. Genetic analyses using mitochondrial cytochrome C oxidase 1 gene revealed that P. juhuae is closely related to P. bhujia, being separated by a genetic distance of 1.5%. However, the current species is conspicuously distinct from P. bhujia by the presence of a dorsal fin, among other features. A low genetic distance and significant morphological difference between these two Pangio species suggest that they have diverged from an immediate common ancestor and have evolved distinct adaptations to intricate subterranean niches of the region. Compared to P. bhujia and P. pathala, less evolved troglobitic traits reflect that P. juhuae can also be a connecting species in the evolutionary ladder of terrestrial loaches to subterranean ones. Hence, this could also be an instance of possible subterranean speciation of fishes in underground habitats.

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The reproductive biology of Trichiurus lepturus Linnaeus 1758, was studied based on 6167 and 3346 specimens collected weekly along Eastern Arabian Sea (EAS) and Western Bay of Bengal (WBB) respectively during 2014 to 2018. The sex ratio varied significantly (p<0.05) throughout the year with a predominance of females during all months except September and October in EAS while, it did not differ significantly (p<0.05) except during June and July in WBB. The estimated length at first maturity (Lm50) for females was 58.0 cm TL in EAS and 55.5 cm in WBB. Higher Gonadosomatic index (GSI) values were recorded in February and May along EAS and in February and October along WBB. The proportion of ripe and partially spawned fishes were high to moderate during January to May in EAS and during October to March in WBB indicating peak spawning periods for T. lepturus. The presence of ripe, partially spawned, spent and spent-recovering fishes throughout the year in varied proportions implied prolonged spawning throughout the year. Microscopic and histological examination of the ovaries further confirmed T. lepturus to be an asynchronous batch spawner. The estimated absolute fecundity ranged from 21,930 to 1,85,941 [average 28,245±3306 (SE)] and 17,294 to 1,86,667 [average 75,000±10,436 (SE)] per female fish along EAS and WBB respectively. The relative fecundity (per g body weight) varied from 12 to 841 [average 105±12.2 (SE)] and 64 to 241 [average 64±15.1 (SE)] in EAS and WBB respectively.

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Economic burden of diseases on Indian aquaculture sector was estimated to be US$ 2.48 B, 14.95% of annual aquaculture production value. Analysis revealed a higher cost of disease (US$ t−1) in shrimp (1,224.82) followed by marine fish (815.87), IMC+ (364.89), tilapia (260.34), IMC (200.70), and pangasius (pond 198.92; cage 168.36). The major contributors to the disease burden included production loss (23.90%), expenses on prophylactics (50.31%) and therapeutics (17.26%). The economic loss was dominated by diseases of multiple etiology (US$ 468.27 M), bacterial hemorrhagic septicemia (US$ 326.47 M), and epizootic ulcerative syndrome (US$ 88.12 M) in finfish and by Enterocytozoon hepatopenaei infection (US$ 571.24 M) in shrimp. Multinomial logit regression identified farm size, water source and exchange, stocking biomass and feed type as the main determinants of disease. The study findings would assist in prioritizing resource allocation and developing intervention strategies at the national level for effective and targeted disease management.

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Portunus sanguinolentus is widely distributed all along the Indian coast and the most dominant marine crab landed in the country. In Kerala also, species share is maximum in the marine landings and recorded an average landing of 1200 tonnes during 2007-2018. The bulk of the catch is contributed by trawlers and the species is mainly fished from 20-30 m depth zone. It grows to a maximum size of 20 cm in carapace width (CW) and the estimated life span is approximately three years. Knowledge on the body weight-length/width relationships and relative condition factor in populations is important for estimating the population size of a stock and its exploitation. Hence, the interrelationships between various morphometric characters, viz., Carapace Width (CW) and Length (CL) and Chelar Propodus Length (CPL) and Height (CPH) in males, as well as Carapace Width and length and Abdominal Width (AW) and Length (AL) in females, were estimated using a total of 2476 male and 2965 female crabs. The Carapace Width/Length-Weight relationship was studied in both sexes on a total of 5595 crabs using the allometric growth equation. The allometric relationships between the characters of this set suggest that most relationships are positive and highly significant (P ≤ 0.01). The ‘b’ values for carapace width-weight in males (55-171 mm/CW), females (54-170 mm/CW), and pooled were 2.9657, 2.8028, and 2.8914 respectively. The results show an isometric growth pattern for males and considerable deviation from isometric growth in females and also when all sizes are pooled. An analysis of covariance indicates that there is a significant difference between sexes (P ≤ 0.01) with respect to the carapace width-weight relationship. The condition factor values estimated in males and females (based on CW) were 0.942 ± 0.145 and 1.371 ± 0.255 respectively and the estimated Kn values based on CL were 0.985 ± 0.204 and 1.022 ± 0.233 respectively.

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