Marine capture of Sphyraena putnamae along western Bay of Bengal has been increasing. Owing to scarcity of information available on feeding dynamics globally, the present study was conducted using 763 individuals captured during 2017–19, to decipher trophic ecology and relationships. Of the individuals analysed, 54.8% had their stomachs either empty or with trace amounts of food, 27.3% had part-full stomachs and 18.0% had full stomachs. Stomach vacuity and fullness as well as predator–prey weight ratio varied with increase in body size, implying higher feeding intensity in large-sized fishes. Feeding activity was highest during July–November and lowest during March–April. The species is an opportunistic piscivorous pelagic predator that feeds on teleosts (>85%) and cephalopods. Sardines were the major prey, followed by whitebait, squid, bigeye scad, Indian scad, silverbellies and Indian mackerel. Diet contents were similar between sexes (82.17%); however, it varied among seasons (56.86–69.85%). Shifts in prey preferences from sardines, squid and bigeye scad to ribbonfish, shad, grunter, Indian mackerel, horse mackerel and Acetes were observed with increase in fish size, and diet varied between individuals sized <60.0 and >60.0 cm. Trophic level value was 3.51 ± 0.13 and Levin's Standardized Niche Breadth Index was 0.21. Dietary niche breadth varied across seasons and sizes, with higher values during summer and winter (0.36–0.41) and in fish measuring >45.0 cm (0.50–0.68), which implies generalized feeding behaviour. The present study represents the first detailed report on the diet of S. putnamae and will provide a substantial contribution to stock management through understanding of trophic interactions.

No prior comprehensive information on the reproductive biology and trophodynamics of Aluterus monoceros was globally available. The present study was performed on 1036 individuals landed along the western Bay of Bengal during 2017 to 2019. Length ranged between 25.3–64.4 cm in females (mean at 48.34 cm) and from 21.5–64.1 cm in males (mean at 47.83 cm). Growth was negatively allometric with no significant difference between sexes. Sex ratio (F:M) was 1.03 with variations based on sizes and months. Size at sexual maturity for females and males was 40.85 and 41.60 cm, respectively. The species spawned throughout the year with major and minor peaks during February to May and October and November. Absolute fecundity increased linearly with length and weight and ranged from 33,640 eggs to 12,39,202 eggs. Stomachs were empty or with trace amounts of food in 59.17%, part-full in 34.07% and full in 6.76% of the fishes. Stomach vacuity and fullness and predator–prey weight ratios varied with an increase in body size, implying higher feeding intensity in large-sized fishes. Feeding activity was more intense during June–August and less during the peak spawning months. The species is omnivorous and a bottom feeder. Teleosts contributed the most to the prey items (43.23% by Index of Preponderance) implying preference for carnivory. Ontogenetic shifts and seasonal variations in prey items were observed. The present study provides paramount information that can significantly contribute to the management and conservation of monacanthid stocks in northern Indian Ocean.