Quantitative and qualitative aspects of energy acquisition of the cichlid fish Oreochromis niloticus L.

A unified theory of fish growth and feed intake was proposed with the aid of a conceptual growth model. Feeding experiments were performed with individuals and groups of Oreochromis niloticus (L) (2-50g in weight) using diets with differed biochemical composition. The functional relationship between growth and feed intake was found to be linear, irrespective to the growth indices is used as the dependent variable. The protein and energy requirement of O. niloticus was quantified and maximum requirements of 2 - I2g fish was approximately 22g protein kg**BW day** or 990 kJ-* kg**BW day**. In terms of mammalian physiological fuel values. The requirements of fish of 18 - 50g weight range was approximately 12g protein kg** BW day*’ with a corresponding energy intake of 650 kJ’’ kg*’BW day*’ for the maximum growth. Feeding fish above those limits resulted in a slight retardation of growth. The maintenance requirements were computed with the regression curves of growth and feed intake and found to be vary depending upon the equation used. The digestibility coefficients of protein, lipid and carbohydrates ware established to be as high as 90%, and the coefficients did not change over the weight range of the experimental fish. The optimum non-protein and protein energy ratio (NPE/PE) for O. niloticus was 1.72 and NPE was further analysed into lipid (LE) and carbohydrate energy (CE). It was found that the LE/CE ratio for O. niloticus is 2.25 in terms of mammalian physiological fuel values. A development of the conceptual growth modal for predictive growth modelling was discussed

EFFECT OF STOCKING DENSITY ON THE CULTURE OF SILVER BARB (Barbodes gonionotus) lN FERTILIZED PONDS

The effect of stocking density on the culture of silver barb (Barbodes gonionotus) was evaluated in this experiment

POTENTIAL OF NOSTOC MUSCORUM CULTURED IN BG-II MEDIUM AS BIODIESEL FEEDSTOCK SOURCE: EVALUATION OF NUTRIENT REQUIREMENT FOR CULTURE AND ITS DAILY LIPID CONTENT

Increment of industrial development and energy demands for transportation and electricity have increased diesel-fuel uses to fulfil global energy needs. Carbon emission as impact of high fossil diesel use which pollutes the air gradually increases green house gases (GHG) and increases the intensity of acid rains. Furthermore, scarcity of fossil-fuels resources has caused high price of diesel-fuel which in turn to have increased the prices of all commodities. Nostoc muscorum is filamentous Cyanobacteria species which lives both terrestrial and freshwater aquatic environment. This strain has good ability in producing high biomass and potential in producing lipid. In where, Nostoc muscorum has potential as biodiesel feedstock alternative of food-plants sources. This study was conducting to evaluate the potential of Nostoc muscorum cultured in BG-II medium as biodiesel feedstock source. Evaluation of the nutrient requirement of Nostoc muscorum cultured in BG-II medium was done through assimilation of nitrate (NaNO3)-phosphate (K2HPO4). Biomass production as growth parameter was measured by weighing the dried biomass for 14 days of culture. Daily lipid production was evaluated by lipid extraction using Soxhlet method. The result showed that Nostoc muscorum cultured in BG-II medium required 644.6795 mg/L of NO3- and 25.1566 mg/L of HPO4- with the highest biomass production 0.21 grams/300 mL. Furthermore, Nostoc muscorum as multicellular Cyanobacteria could grow well in BG-II medium at SGR 0.0964 μ/day. Lipid production of Nostoc muscorum during cultivation in BG-II for 14 days decreased day by day. The highest lipid production was reached up in day 4th of culture that was 9.53 mg/g. Based on this study, Nostoc muscorum has good potential as biodiesel feedstock through producing high biomass in BG-II medium. Keywords: Nostoc muscorum, Synechococcus elongatus, Tofu wastewater, Lipid content, Cell disruption, Biodiesel.

Optimization of Phosphorus Fertilizer in Supplemental Feed‐Fed Based Nile Tilapia (Oreochromis niloticus) Ponds

An experiment was conducted in earthen ponds at the Asian Institute of Technology, Thailand to determine different phosphorus fertilizer dose effects on Nile tilapia production, water quality variables, nutrient utilization and cost‐benefit under supplemental feeding. Five phosphorus fertilization rates were used as treatments e.g. 100%, 75%, 50%, 25% and 0% of 7 kg P ha week−1. Nitrogen fertilization rate was fixed at 28 kg N ha week−1 for all the treatments. Sex‐reversed Nile tilapia were stocked at 3 fish m−2, and 30% CP floating feed fed at 50% satiation feeding rate. Nutrient budget showed higher phosphorus fertilizer input resulted in higher phosphorus sink in the sediment. Mean weight, mean weight gain, daily weight gain and net yield were not significantly different among treatments (P > 0.05). Total Kjeldahl nitrogen, total phosphorus and soluble reactive phosphorus were significantly different among treatments. Economic analysis showed phosphorus fertilization resulted in positive net returns. Though the gross income was not affected by different fertilization rates, significantly lowest cost was found in the treatment using 25% phosphorus fertilizer. It can be concluded from the research that 25% phosphorus fertilization might be used as an alternative strategy of Nile tilapia pond culture in terms of economic return and nutrient loss in sediment.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/115936/1/are12444.pd

The hydroponic production of lettuce (Lactuca sativa L) by using hybrid catfish (Clarias macrocephalusxC. gariepinus) pond water: Potentials and constraints

An experiment was conducted at the Asian Institute of Technology, Thailand, for 54 days to investigate on the effect of pond water filtration and aggregates (hydroponic substrates) on lettuce (Lactuca sativa L.) production, nutrient uptake and growth. A 2x3 factorial experiment consisting of 2 filtration regimes (unfiltered versus partially filtered pond water) and 3 aggregates (styrofoam as control, sand, and gravel). The hydroponic units were placed on a bamboo platform across the pond surface. An earthen pond (226m2) was stocked with 8000 hybrid catfish with an average initial weight of 6.58±1.72g. The fish were fed with commercial pelleted feeds containing 30% crude protein. Twenty-one days old lettuce seedlings were transplanted on to hydroponic units after stocking catfish for 4 months in the pond. Pond water was partially filtered by using a settling tank and filtration tank, which contained netting materials to trap solids. Lettuce plots were irrigated twice daily at 0800 and 1600h using either filtered or unfiltered pond water for 45min. The highest head weight and yield of lettuce were observed with plants grown on the sand media followed by gravel and the control treatments. Partially filtered pond water treatments had significantly higher lettuce yield (PCatfish Filtration Hydroponics Lettuce yield Nutrient uptake and pond water

The Transition from Unregulated to Regulated Fishing in Thailand

Marine fishery is an economically important sector and the primary source of livelihood for coastal fishers in Thailand, but the open access harvesting system and overfishing have depleted fish stocks. The country should address both the issues to sustain a healthy marine fishery and protect the lucrative export market as well as to maintaining seafood self-sufficiency. This paper explains the on-going processes of implementing the measures of restricting the number and size of fishing vessels and fishing efforts to control fishing capacity. The marine resources in the Gulf of Thailand and the Andaman Sea are categorized into three separate species groups: (1) demersal, (2) pelagic, and (3) anchovies. The precautionary approach is used as the guiding principle, and maximum sustainable yield (MSY) of the three combined resource categories is used as a reference point in setting the total allowable catch (TAC) limits in this exercise. The number of fishing days per vessel per year is stipulated by issuing licenses based on the TAC size and total allowable effort (TAE). Both the advantages and disadvantages of the current fishing allocation system are discussed

Effect of Water Recirculation Duration and Shading on Lettuce (Lactuca sativa) Growth and Leaf Nitrate Content in a Commercial Aquaponic System

International audienceTwo experiments were conducted to evaluate the effects of three water recirculating duration (daytime (07.00hto18.00h); nighttime (18.00h to 07.00h); and 24hours control) and shading (30%, 60% and no shading control), respectively, on growth and sap’s nitrate content of lettuce in a commercial aquaponic system integrated with red tilapia culture. First experiment showed that water recirculating time did not affect the lettuce growth, thus offering the possibility to increase aquaponics profitability by reducing the operational cost. The second experiment revealed that shading affected nitrate content in the sap of the leaf midribs, but it remained in range specified by EU regulations in all treatments. The highest lettuce growth was observed at the rate of 30% shading whereas 60% shading gave the lowest growth (P<0.05)

Replacement of dietary fish oils by alpha-linolenic acid-rich oils lowers omega 3 content in tilapia flesh

A 20-week feeding trial was conducted to determine whether increasing linolenic acid (18:3n-3) in vegetable oil (VO) based diets would lead to increased tissue deposition of 22:6n-3 in Nile tilapia ( Oreochromis niloticus). Five isonitrogenous and isoenergetic diets were supplemented with 3% of either linseed oil (LO), a mixture of linseed oil with refined palm olein oil (PO) (LO-PO 2:1) and a mixture of refined palm olein oil with linseed oil (PO-LO 3:2) or with fish oil (FO) or corn oil (CO) as controls. The PO-LO, LO-PO and LO diets supplied a similar amount of 18:2n-6 (0.5% of diet by dry weight) and 0.5, 0.7 and 1.1% of 18:3n-3, respectively. Increased dietary 18:3n-3 caused commensurate increases in longer-chain n-3 PUFA and decreases in longer-chain n-6 PUFA in the muscle lipids of tilapia. However, the biosynthetic activities of fish fed the LO-based diets were not sufficient to raise the tissue concentrations of 20:5n-3, 22:5n-3 and 22:6n-3 to those of fish fed FO. The study suggests that tilapia (O. niloticus) has a limited capacity to synthesise 20:5n-3 and 22:6n-3 from dietary 18:3n-3. The replacement of FO in the diet of farmed tilapia with vegetable oils could therefore lower tissue concentrations of 20:5n-3 and 22:6n-3, and consequently produce an aquaculture product of lower lipid nutritional value for the consumer

The FAD fishery in the Gulf of Thailand: time for management measures

Fish aggregating devices (FADs) used in the Gulf of Thailand are made of bamboo poles, twisted wire and coconut leaves, fastened to a concrete block. Purse seines with 2.5 cm mesh size are used to surround the fish, using fishing boats ranging from 18 to 26 m in overall length. Fishing grounds are located in the central Gulf of Thailand at a depth of 25–60 m. Catch per unit effort (CPUE), species composition and size of economically important species were analyzed by collecting data from fishing boats using FADs at nine main fishing ports along the Gulf of Thailand between January and December 2007. The results show that the average CPUE was 3351 kg day-1, which was composed of 88% pelagic fishes, 5% demersal fishes, 4% trash fishes and 2% squids and cuttlefishes. The major pelagic species were Indian mackerel (Rastrelliger kanagurta), Indian scad (Decapterus russelli) and bigeye scad (Selar crumenophthalmus), which made up 25%, 24% and 8% of the total catch, respectively, while neritic tunas (kawakawa; Euthynnus affinis, frigate tuna; Auxis thazard thazard and longtail tuna; Thunnus tonggol) made up 8% of the total catch. The mean length of ten economically important species was smaller than their size at first maturity, while two species were above their size at first maturity. The results indicated that juvenile fish were mostly being caught by FAD fishery, and this may lead to depletion in fisheries resources and economic loss. Although there is a set of measures to control the use of purse seines, effective management of the FAD capacity is also urgently needed

The nutritional value of lipids in various tropical aquatic animals from rice-fish farming systems in northeast Thailand

Knowledge on the lipid compositions of tropical freshwater aquatic animals is limited despite their importance in the human diet and the health-related benefits of fish lipids. This study examines the lipid content and fatty acid composition from the edible muscle tissue of some common freshwater aquatic animals that inhabit rice fields in Thailand, namely snakehead (Channa striatus), Gunther's walking catfish (Clarias macrocephalus), climbing perch (Anabas testudineus), blackline rasbora (Rasbora borapetensis), swamp barb (Puntius brevis), and freshwater prawn (Macrobrachium nipponense). All specimens were low in muscle fat (&le;1.1% of wet weight). There was considerable variation in the fatty acid composition between species. All species were good sources of the essential fatty acids, and particularly of C22:6n-3 (5.2&ndash;13.3% total FA) and C20:4n-6 (7.2&ndash;14.6% total FA), signifying their high nutritional quality for human nutrition. The findings indicate that strategies for rural development, food security, and alleviation of poverty in rural areas need to pay special attention to the management of aquatic resources to ensure the health and well-being of rural people