Abstract: The development of Argyrosomus regius early development stages (embryonic, yolk sac and newly larval) was studied, with emphasis on yolk and lipid absorption. The effect of a progressively delayed initial feeding on the feeding ability and survival of this species was also examined. The number of days from hatching after which the feeding rate dropped to half the initial highest feeding rate or the point of no return (PNR) was determined. In May of 2010, the experimental eggs were obtained by natural spawning from captive broodstock (F₁ generation cultured specimens). The embryo, yolk sac and larval stages of meagre were reared in laboratory conditions on temperature of 19°C and 35ppt salinity. Eggs present a diameter of 1.056±0.010mm, a volume of 0.616mm³ and a wet weight of 0.718±0.033mg, while they contain one lipid globule of 0.265±0.005mm diameter and 0.010mm³ volume. The total length of meagre larvae after hatching and at the onset of exogenous feeding was measured 2.621±0.037mm and 3.492±0.051mm, respectively. The yolk sac reserves were consumed 60h after hatching, while the reserves of oil globule exhausted 156h after hatching. The percentage of larvae with visible gut contents was maximal 108h after hatching and decreased to half (PNR) just 12h after this point or 120h after hatching. The findings indicate a high rate of food demand for this species.

Abstract: The effects of Clove Seed extracts as anaesthetic agents in two species of grey mullets Liza Falcipinnis and Liza grandisquamis were assessed. A total of 120 of these species comprising 60 L. Falcipinnis with 30 each of fingerlings (mean length 9.86cm ± 1.11 SD: mean weight 21.20g ± 2.10 SD) and juveniles (mean length 17.24cm ±1.88 SD; mean weight 66.24g ± 4.24SD) and 60 L. grandisquamis also consists of 30 each of fingerlings (mean length 10.24cm ± 1.92 SD; mean weight 23.41 ± 2.21 SD) and juveniles (mean length 18.21cm ±SD; mean weight 71.21g ± 4.12 SD) were sampled from the recruitment ponds at African Regional Aquaculture Center, (ARAC), Buguma, Rivers State and were exposed to clove seed extracts at different concentrations of 0.0mg/L (control), 5.0, 10.0, 15.0, 20.0 and 25.0mg/L. The results obtained indicated a size related response, to Clove seed extracts. The induction time in both species were found to decreased significantly (P < 0.05) as the concentrations of the clove extracts increased with the shortest induction time 55.61(s) observed in fingerlings of L. grandisquamis, while the longest 210.61 (s) was recorded in juveniles of L. falcipinnis. However, the recovery time increased significantly with increasing concentration of the clove seed, with the highest recovery time of 350.11 (s) observed in L. falcipinnis, at 25.0mglL concentration and the lowest 246.91(s) in L. grandisquamis at 5.0mg/L concentration of the clove extracts, with the optimum dosage of 10.0mg/l and 15.0mg/l for fingerlings and juvenile sizes respectively. Interestingly, the survival of the exposed fish during the trial was 100% in both sizes of the two species,as no mortality was recorded in all concentrations of the plant extracts. The findings of this trial, indicated that clove seed extracts was effective, producing minimum stress and zero mortalities and therefore can be recommended as an effective anaesthetic for use in aquaculture.

Abstract: Microalgae have been widely used as novel sources of bioactive substances. Along with this trend, the possibility of replacing synthetic preservatives with natural ones is receiving much attention. In general, microalgae are rich in various phytochemicals like carotenoids, phycocayanine, phenolics, amino acids, polyunsaturated fatty acids, and sulphated polysaccharides. These compounds are providing excellent various biological actions including, antioxidant, antimicrobial, antiviral, antitumoral, anti-inflammatory and anti-allergy effects. Their healthy benefit seemed to be due to different biochemical mechanisms. However, some microalgae species such as Chlorella, Spirulina and Dunaliella species have been used in several areas in nutraceutical, pharmaceutical, cosmetics, nutrition and functional quality of foods. In 2006, World Health Organization has been described Spirulina as one of the greatest super-foods on earth serving as an example of the potential of microalgae. This review provides background on current and future uses of microalgae as novel source of health promoting compounds.

Abstract: The present study was undertaken to observe the fish marketing chain through a number of intermediaries such as, local fish traders, paikers, wholesalers and retailers in 5 arbitrarily selected markets (Belua Bazar, Gopalpur Bazar, Nandanpur Bazar, Suti Bazar and Alamnagar Bazar) in Gopalpur upazila under Tangail district. A total of 50 traders were selected (10 from each market) for personal interview and focus group discussion. Traders typically operated with capital of around Tk.5000 to 15000/day. Among the cultured species, Rohu, Catla, and Mrigal fetched higher prices (Tk.120-250/kg) and price depends on market structure, species, quality, size and weight. It was observed that under market channel I (Fish farmer – Paikers- Wholesalers- Retailers- Consumers), fish farmer’s gross price per quintal of fish was Tk. 9000. Similarly for channel II (Fish farmer -Wholesalers- Retailers- Consumers) the price spread was Tk. 1605 per quintal of' fish, while the fish farmers gross share was 82.16% of consumers price. In case of channel III (Fish farmers-retailers- consumers) the price spread was Tk. 1087 per quintal of fish while the fish farmer’s gross sale was 87.92 %. Therefore, in term of farmer’s share, the performances of channel III was relatively, much better than those of other channels. A number of constraints during fish marketing were reported by traders including higher transport cost, poor road communication and transport facilities, poor supply of ice, and exploitation by middlemen. In spite of socio-economic constraints, most of the household’s of the traders (80%) have improved their status through fish marketing activities.

Abstract: The age and growth of the freshwater clam Galatea paradoxa from the Volta River estuary, Ghana was estimated during a two-year study using surface growth rings, length-frequency distributions and tagging recapture experiment. Mean lengths at ages 1 to 8 years were 19.4, 28.4, 37.1, 44.1, 49.5, 55.5, 65.6 and 73.1 mm, respectively. The von Bertalanffy growth curves obtained by three the methods were: L_t = 80.4(1-e^-0.17t), L_t = 105.7(1-e^-0.14t) and L_t = 104.5(1-e^-0.16t) for surface rings, length-frequency distributions and tagging recapture respectively. All the age determination methods were successful in estimating the age of G. paradoxa indicating that surface ring counting is an appropriate and reasonably accurate method for simple and rapid age estimation in this species. The estimated growth curves obtained from surface rings, length-frequency distributions and the tagging-recapture experiment revealed that the methods provided similar estimates of growth rates.

Abstract: The present investigation was carried out to determine existing fish species status, fish catch composition, fishing seasons, fishing gears, fishers socio-economic welfare and the fisheries management practices of Dogger beel in Hajigonj Upazilla of Bangladesh. The study revealed that a total of 58 fish species belong to 21 families under 9 orders were identified in the beel. Among them 44 species were small indigenous species (SIS) and the rest 14 species were large where 6 of them were exotic species. The maximum fish species (16) were under Cyprinidae family. Four families (Ambassidae, Channidae, Anabantidae and Palaeomonidae) represented 4 species each and another four families (Clupedaei, Schilbeidae, Bagridae and Mastacembelidae) represented 3 species each, and rest thirteen families represented 1 to 2 species each. Thirteen different kinds of fishing gears were identified under 5 major groups including 5 nets (current jal, ber jal, thela jal, jakhi jal and dharma jal), 3 traps (unta chai, bitte chai and icha chai), 2 hooks (chip borshi and chara borshi), 2 spears (teta without hooks and teta with hooks) and khata/zag in the beel. Three types of fishers were engaged in fishing in the Dogger beel. The highest catch was recorded in October (402 kg/month) and the lowest catch was recorded in June (213 kg/month). The highest number of fishers (85) observed in the monsoon period and the lowest number of fishers (33) observed in the dry season involved in fishing. Most of the fishers used current jal and spears where few of them were used dharma jal for fishing. The maximum 45% of the fishermen had medium size family, 32.5% had large size family and the rest 22.5% had small size family. Among the total fishermen 45% had primary or higher level education and 32.5% can sign their name while about 22.5% of them were illiterate. The average annual income of the professional fishers was BDT 61,375 only.

Abstract: Tilapia is one of the most productive and internationally traded food fish in the world. The production of farmed tilapia is among the fastest expanding food sectors in the world. Nile tilapia (Oreochromis niloticus) is the most cultured freshwater species among the farmed tilapia and contributes about 71% of the world total tilapia production. In Nigeria, Tilapia culture is a promising aquaculture business. In this study, we estimated the economic profitability of small-scale production of O. niloticus in semi flow-through system at three stocking density using the profitability index and the viability index. The economic profit indices measured were Gross profit, profit index and incidence of cost while the viability index was benefit/cost ratio. These were computed from the record kept during the experiment, which included stocking densities, type of feed used, labour cost, and other input cost. The results of the experiment suggested that fish fed Multi-feed were more profitable than those feed NIOMR feed. The results generated can guide farmers to develop standard farm enterprises and business plans.

Abstract: Concentrations of ten essentials and non essentialstrace metals Hg, Mg, Fe, Zn, Cu, Ni, Cr, Cd, Pb and Co were determined in the muscles of two squids (Loligoduvauceli; n=24, Sepioteuthislessoniana; n=27) and one cuttlefish (Sepia latimanus; n=12) species collected from Kalpitiya and Mannar area of Sri Lanka in 2010. Trace metals were analysed using Varian Atomic Absorption Spectroscopy (VGA, GTA and Flame AAS). The mean values of all trace metals in muscles of studied species were within the international safety limits and pooled mean concentration of trace elements were following order; Mg > Zn > Cu > Fe > Cr > Ni > Hg > Cd > Co >Pb.