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The Gangetic hairfin anchovy, Setipinna phasa (Hamilton, 1822) were collected from river Ganga (Kanpur) and Hooghly estuary (Kolkata) to study the comparative reproductive traits (sex ratio, spawning season, gonado-somatic index, fecundity and egg diameter). Female outnumbered the male in the population of river Ganga but it was non-significant in the population of the estuary. Five maturity stages were identified in males and females of the fish of both ecosystems. Occurrence of multimodal (immature, maturing and mature) and uni-modal (matured) type of ova in the ovary of the fish of Hooghly estuary and river Ganga respectively and the values of gonado-somatic index confirmed the double and single spawning in a year in the fish in estuary and river respectively. The absolute fecundity was found to be higher in the fish of river Ganga compared to that of the estuary (P < 0.05). Linear and positive correlations between fecundity and the total length, body weight, ovary length and ovary weight were noted in the fish of both ecosystems (R2 > 0.90). The present study provides the comparative account of the reproductive and spawning strategies of S. phasa for the first time in favour of the proper management and conservation of the fish.

Dietary composition and feeding intensity in relation to season, size and maturity stages of the Gangetic hairfin anchovy Setipinna phasa (Hamilton, 1822) were investigated in the present study. Strong dentition, modified gill rakers, strongly built stomach and short intestine were some of the basic characteristics associated with the feeding habits of S. phasa. Relative length of gut (RLG) indices indicated the absence of any major shift from basically carnivorous orientation of the fish during its various life stages. Feeding intensity was relatively high in stage III (gonad ripening stage) and low in the stages IV and V (ripe and spent). Insects and crustaceans were the main food of adults while annelids and insects were eaten by juveniles. Adult individuals of river Ganga consumed more food during winter than summer and rainy seasons, while the food intake in adult specimens of Hooghly Estuary was greater during summer compared to winter and rainy seasons. Study of food and feeding habits of fishes provides base line information for facilitating fisheries management programmes and sustainable aquaculture.

Ten fresh fish samples of different species (Mugil cephalus, Setipinna phasa, Coilia dussumieri, Scatophagus argus, Sillanopsis panijus, Arius caelatus, Hilsa ilisha, Polynemus paradiseus, Platicephalus indicus and Pelamys chiliensis) collected from Kuakata, Bangladesh were assessed biochemically (proximate composition, total volatile basic nitrogen, tri-methyl amine and pH). Moisture content of fresh fish varied over a range from 65.33 to 78.92%. Likewise, protein (8.58 to 19.06%), fat (6.12 to 12.99%) and ash (1.07 to 8.41%) content indicated wide variation in the ten fresh fish analysed. TVB-N and TMA-N values of fresh fish were found ranging between 10.92±0.23 to 25.75±0.80 mg N 100 g G and 7.70±0.67 to 18.50±0.77, respectively. The 1 values of pH of the samples ranged from 7.03±0.05 to 6.7±0.07.

A shape factor was introduced in the growth equation for S. phasa (Ham.) based on Von Bertalanffy's growth model and allometric growth. The estimates thus obtained fit the observed values better than those obtained with the assumption that growth is isometric. A new method of evaluating shape factor is described.