‘Sensory pad’: a novel chemoreceptive device in Hilsa (Tenualosa ilisha) to support its amphihaline attribute

Hilsa, Tenualosa ilisha is an amphihaline migratory fish that performs spawning migration to selected freshwater rivers in Indo-Pacific region. It is not clear what force triggers its migration. In this paper, we attempted to describe the features of outer integument from its head region as chemosensory site which appears to play significant role in its upstream migration. We found that this area (termed as snout) has very soft and scale less tissue oriented with pit like grooves named as ‘epidermal pit’. Around these pits, odorant receptor G-protein subunits (Gαq, Gαs/olf and Gαo) have been substantially localized. Use of DASPEI also traced this area with neuronal existence. These features in the snout likely to contribute for chemosensory requirements of the fish during upstream migration. Considering such findings, we named this area of snout as ‘sensory pad’. Its position at the forefront of olfactory organ and brain may have important role in facilitating sensory reception by the fish swimming upstream to the river

First record of the immaculate puffer fish, <em>Arothron immaculatus</em> (Bloch and Schneider, 1801) from Chilika lagoon, India

1011-1013The immaculate puffer fish, Arothron immaculatus was recorded for the first time from Chilika with a single specimen (TL: 107.9 mm) collected from the outer channel sector, adding a new record to the ichthyofaunal diversity of finfish species from the lagoon

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Not AvailableSuccessful captive broodstock development of clupeid fish, hilsa, is one of the major challenges for the artificial propagation of this economically valued fish. The present study provides novel insights into the pond-reared captive broodstock development of hilsa using artificial feed. In the present study, wild collected hilsa fry (weight 1.35 ± 0.13 g, length 53.84 ± 0.95 mm) were reared in grow-out ponds for 6 months followed by maintaining them as broodstock in other ponds using formulated feed in both cases. After 6 months of pond rearing, the average body weight and length of fish were 66.76 ± 4.53 g and 184.75 ± 3.65 mm, respectively. In broodstock ponds, hilsa subadults fed with formulated feed (crude protein 41.06%) ensured significant advancement in ovarian maturity with gonado somatic index of 9.09%, enhanced secondary yolk stage oocytes of 91.66% and enlargement of oocyte diameters up to 570 μm. The broodstock reached somatic growth such as average body weight and average body length of 383.80 ± 27.38 g and 339.33 ± 9.68 mm, respectively, with a condition factor of 1.06 ± 0.15. Gut content analysis revealed the better acceptability of the artificial feed. Lipid profiling of muscle and ovary during gonadal maturation revealed mobilization of fat from muscle to ovary and selective retention of some fatty acids (i.e., C14:0, C18:0, C20:5, C22:6 and C20:4) in the ovary, which might help in gonadal maturation.Not Availabl

Vermiculated sailfin catfish, Pterygoplichthys disjunctivus (Actinopterygii Siluriformes: Loricariidae): Invasion, biology, and initial impacts in east Kolkata Wetlands, India

Background. The East Kolkata Wetlands in India (a Ramsar site) are sewage-fed, nutrient-rich water bodies successfully used for fish production. The vermiculated sailfin catfish, Pterygoplichthys disjunctivus (Weber, 1991), exotic to India, has invaded these wetlands. The management and control of this catfish has been hindered, because of the lack of information on its abundance, population structure, biological traits, level of establishment, and competition with native fish species. Materials and methods. Within 2013–2015 studies were carried out on the population structure of P. disjunctivus, its food habits, reproductive biology, and initial impacts in the wetlands through monthly and seasonal collection of samples, examination of food items, reproductive parameters, catch data, and gathering fishers experience. Results. The length (TL) and weight of the specimens ranged from 10 to 55 cm and from 120 to 1250 g, respectively. Major food items of the catfish were detrital matter (%IRI 56), unidentified plant matter (%IRI 11), fish eggs (%IRI 11), polychaete worms (%IRI 5), and other minor items (%IRI 0.3 to 4). At 50% similarity, the food items of P. disjunctivus overlapped with that of Macrognathus pancalus, Channa punctata, Nandus nandus, Anabas testudineus, Clarias batrachus, Oreochromis niloticus, Cirrhinus mrigala, and Cyprinus carpio while at 80% it overlapped with that of C. mrigala and C. carpio. The fecundity of P. disjunctivus, in the wetlands, was the highest recorded for the species. Females attained the first maturity at 24 cm TL and reproduced multiple times within July–November. The breeding period of the species overlapped with 13 native fish species, of which it seriously overlapped with that of Gudusia chapra, Amblypharyngodon mola, Pethia conchonius, P. ticto, N. nandus, C. punctata, and A. testudineus. The sailfin catfish has established reproducing populations in the wetlands and reached ‘invasive’ proportions constituting 4.83% (300.04 t · year–1) of the mean annual fish catch (6203.85 t · year–1) from the wetlands. The invasive risk assessment showed a high risk of the species in the current scenario and probable climate change scenarios in future in the region. Conclusions. Pterygoplichthys disjunctivus has successfully colonized the sensitive East Kolkata Wetlands, which might easily spread to neighbouring water bodies including the sensitive Ganga River and Sundarban mangroves and cause ecological and economic disturbance unless preventive measures are taken as the species has high invasive risk in the region.Water Resource