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Vermiculated spinefoot, Siganus vermiculatus has been reported to be one of the fastest growing species among genus Siganus. Even though it breeds in captivity, commercial level hatchery production is yet to be achieved. In the present study, mature brooders of S. vermiculatus (female weighing 400 g and male weighing 385 g) were induced to breed in captivity and the larvae were reared to metamorphosis. Fishes (55 nos., 150 g–700 g) were collected from the wild and reared in marine cages using formulated floating pellets as feed. Among the mature fishes brought to the hatchery, a female having an average ova diameter of 440 μm and a running male were induced with two intramuscular injections of human chorionic gonadotropin (hCG) at the rate of 500 IU/ fish and 200 IU/ fish respectively in a spawning tank. Spawning occurred on the day after the full moon, between 20- and 21 h after the second injection. Fecundity was estimated as 1.85 lakhs with 68–71% of viable eggs and hatching rate of 73–85%. Green water systems with microalgae, Nannochloropsis salina and Isochrysis galbana at a concentration of 2–3 × 106 cells mL−1 and 2–3 × 105 cells mL−1 were used in tanks (1000L) for egg incubation and larval rearing respectively. Copepod, Parvocalanus crassirostris (T1) and enriched rotifer, Brachionus rotundiformis (S-type) (T2) were tested as first feed for newly hatched larvae. The fertilised eggs (0.57 ± 0.02 mm) hatched out between 24 and 25 h and the newly hatched larvae measured 1.92 ± 0.08 mm in total length with a transparent yolk sac (0.63 ± 0.04 mm) and an oil globule (0.23 ± 0.02 mm). Mouth gape of 89.03 ± 9.4 μm was observed after 42 h post hatch. The use of copepod, P. crassirostris as the first feed helped in successful rearing of the larvae to metamorphosis and an improved survival rate (4.5%–12%). Metamorphosis was completed within 35–37 dph, during which post larvae with vermiculated body pattern measured 25.2–28.4 mm in length and 0.28–0.30 g in weight. Enriched rotifers (5–37 dph), copepodites (10–20 dph), umbrella stage of Artemia (18–24 dph), artificial pellet feeds (21–37 dph) and enriched Artemia nauplii (29–37 dph) were also used during various stages of larviculture. The present study is the first report of induced breeding of S. vermiculatus during full moon phase of lunar cycle. The results of the present study also demonstrate a protocol for successful rearing of larvae to metamorphosis with P. crassirostris nauplii as first feed.

Effect of marine microalgal diet on filtration and ingestion rates of Brachionus plicatilis was studied. Marine microalgae viz., Nannochloropsis oculata, Isochrysis galbana, Chaetoceros calcitrans and a combination of N. oculata and I. galbana (Nanno+Iso) at different cell concentrations were selected for the experiment and triplicates were maintained for each feed. Significant difference (p

Growth rates of cage cultured Asian seabass Lates calcarifer (Bloch, 1790) and cobia Rachycentron canadum (Linnaeus, 1766) in relation to the water and sediment quality of marine farm at Karwar for two consecutive crops (2012-13 and 2013-14) were analysed. No significant variation was observed in the specific growth rate (SGR) of both the species between the crops. But within a crop, variations were observed in the SGR and absolute growth rate (AGR) of both the species (p

Investigations were carried out on the bacterial flora of water and the quality of rotifers in outdoor mass culture tanks. Brachionus plicatilis and B. rotundiformis were cultured in 10 numbers of 1 tonne tanks and the physico-chemical parameters and microbial loads of water, and total bacterial and Vibrio loads of microalgae and rotifers, during the period 2014-15, were studied. The study revealed a significant variation of the ammonia levels and total bacterial loads with different diets (P < 0.05). A positive correlation was observed between the total bacterial loads of algal concentrations and loads of rotifers, but no correlation was observed between Vibrio loads of water and rotifers. The prevalence of Vibrio loads of rotifers was low in tanks fed with Nannochloropsis oculata and maximum Vibrio loads were recorded in Chaetoceros calcitrans fed rotifers. The Vibrio loads significantly varied with days of culture and also with the algal diets. A positive correlation was observed between the total Vibrio loads of water and rotifers.