Confirming the authenticity of the geographical origin of Naruto dried wakame Undaria pinnatifida using stable nitrogen isotope ratios

In aquatic ecosystems, the stable nitrogen isotope ratio (δ¹⁵N) of wakame is affected by the δ¹⁵N of its nitrogen source. Thus, the δ¹⁵N of wakame is thought to differ between those grown in different aquatic ecosystems. To confirm the authenticity of the geographic origin of Naruto dried wakame (DW), we conducted δ¹⁵N analysis. The δ¹⁵N (mean ± σ) of Naruto DW model samples (n = 72) was 11.1 ± 1.9 ‰. The δ¹⁵N confidence range of Naruto DW from the model was 5.3–16.9 ‰ (mean ± 3σ). The δ¹⁵N values of the DW model of Chinese (n = 23) and South Korean origin (n = 22) were 4.2 ± 1.4 and 1.6 ± 2.3 ‰, respectively. Within the δ¹⁵N confidence range of Naruto DW, two model samples of Chinese DW and one model sample of South Korean DW were found. From those results, DW of Naruto origin was able to be distinguished from DWs of the Chinese and the South Korean.     

CERTIFICATION OF SHRIMP AND SALMON FOR BEST AQUACULTURE PRACTICES: ASSESSING CONSUMER PREFERENCES IN RHODE ISLAND

This study uses a conjoint experiment to evaluate seafood consumers’ preferences for wild versus farmed seafood in Rhode Island, while providing an option for farmed products to be certified for best aquaculture practices, focusing upon salmon and shrimp. The definition for best aquaculture practices provided to respondents in the survey is broadly based upon standards currently in use by aquaculture certification groups, highlighting sustainability of fish feed, and control of antibiotic use, water quality and stocking density. Using data from an in-person intercept survey, a conditional logit model shows that a sample of 250 seafood consumers in Rhode Island choose wild products over farmed even when farmed products are certified, and by an entity preferred by the consumer. Results warrant both further study of consumer preferences for certified aquaculture products across a broader population, and study of the effect of different explanations of ‘best aquaculture practices’ upon preferences.     

Feeding,somatic condition and survival of sand lance <Emphasis Type="Italic">Ammodytes</Emphasis> sp. larvae in Mutsu Bay,Japan

To clarify the recruitment process of sand lance Ammodytes sp., we investigated larval condition factor, relative gut fullness (%GF), prey abundance and oceanographic structure in Mutsu Bay, Japan, during 1999–2001. Ammodytes sp. larvae, which were collected by horizontal hauls of Motoda nets and a ring net at depths of 1, 10, 20, 30 and 40 m, were mainly distributed at 10–30 m. Larvae at the first feeding time until 12 mm in body length (BL) fed predominantly on copepod nauplii, whereas large larvae with BL of 12.1–14.0 mm fed on a mixture of copepod nauplii, copepodites and appendicularians from late February to April. A path analysis showed that difference in water density between 35- and 5-m depths negatively affected naupliar abundance at 10–30-m depth (standardised path coefficient β = ?0.71, p = 0.005 for 3.3–8.0-mm BL larvae and β = ?0.78, p < 0.001 for 8.1–12.0-mm BL larvae). Naupliar abundance positively affected the %GF of Ammodytes sp. larvae (β = 0.75, p < 0.001 for 3.3–8.0-mm BL larvae and β = 0.66, p < 0.001 for 8.1–12.0-mm BL larvae), whereas it was negatively affected by water temperature (β = ?0.45, p = 0.008 for 3.3–8.0-mm BL larvae and β = ?0.56, p = 0.002 for 8.1–12.0-mm BL larvae), and the temperature effect was weak compared with that of naupliar abundance. In turn, %GF positively affected larval somatic weight (β = 0.91, p < 0.001 for 6.0-mm BL larvae and β = 0.70, p = 0.005 for 10.0-mm BL larvae). The recruitment failure in 1999 was likely caused by a reduced condition factor, which resulted from low naupliar abundance. In contrast, the abundance of nauplii and Oithona similis copepodites was high in 2000 and 2001. It is possible that the higher recruitment success in 2001 was because of the higher water temperatures in Mutsu Bay, sustaining faster growth of the larvae than in 2000 under the high-prey abundance conditions.     

Critical swimming speed and maximum sustainable swimming speed of juvenile Pacific bluefin tuna, Thunnus orientalis

Tank wall collision is one of the major causes of mortality during the early-stage rearing of Pacific bluefin tuna, Thunnus orientalis (PBT). Therefore, to design a rearing environment that meets the needs of juvenile PBT, it is important to gather information about their swimming capabilities. We conducted experiments to examine the relative critical swimming speed (RCSS) and maximum sustainable swimming speed (MSSS) of early-stage PBT. The fish were kept in 3-tonne tanks and fed on artificial pellets every 2 h from dusk to dawn. We conducted two sets of experiments to measure swimming speed; the fish were introduced one at a time into a water funnel, and the water current velocity was gradually increased over time to estimate RCSS, or the water current was kept at a constant velocity to estimate MSSS. We measured the RCSS of 72 PBT juveniles (24–29 days after hatching (DAH); standard length (SL), 15.0 ± 2.3 mm) and the MSSS of 32 PBT juveniles (28–37 DAH; SL, 20.0 ± 5.1 mm) in the laboratory. The RCSS ranged from 4.7 to 20.3 SL/s (average, 12.4 ± 3.3 SL/s), and the MSSS was estimated to be approximately 4 SL/s. We speculate that introducing a water current in the rearing tank of no more than 4 SL/s could positively affect the survival of juvenile PBT.     

Optimum low salinity to reduce cannibalism and improve survival of the larvae of freshwater African catfish <Emphasis Type="Italic">Clarias gariepinus</Emphasis>

The freshwater African catfish Clarias gariepinus is carnivorous and cannibalistic even during the larval and juvenile stages and this behavior causes economic losses in aquaculture. This study examined for the first time the effect of salinity on cannibalism, survival, and growth of African catfish larvae in the hatchery. Larvae (4 days old, median 7.8 mm TL, 2.8 mg BW) of the African catfish were reared for 21 days at nominal salinity 0, 1, 2, 3, 4, 5, 6, and 7 ppt. After 21 days, they grew to 10–39 mm (median 22 mm) and 10–490 mg (median 90 mg), with no significant difference by salinity treatments. Survival ratios were similarly low (24–31%) at 0, 1, 3, and 7 ppt and significantly higher (49–55%) at 2, 4, 5, and 6 ppt. Cannibalism was significantly lower, 15–30% at 4–6 ppt, than the 40–50% at 0–3 and 7 ppt. Size variation was lower at 4–6 ppt and higher at 0–3 and 7 ppt. We recommend hatchery rearing of African catfish at the optimum low salinity of 4–6 ppt rather than in full fresh water at least up to 21 days. This rearing method fosters larval welfare and improves hatchery production.     

Consumer Preferences for Live Seafood in the Northeastern Region of USA: Results from Asian Ethnic Fish Market Survey

Asian ethnic fish markets in the Northeastern region of the United States of America (USA) are popular for selling live fish and seafood. A consumer survey was conducted in selected supermarkets of New York, New Jersey, and Pennsylvania during the summer of 2009 to assess consumer preferences for live seafood species. A binary logit model was developed to study the factors influencing preferences for live and fresh fish products. Results indicated that consumer preferences for live fish species vary by ethnic group. Live fish customers visited supermarkets at least two to three times a week and spent $16 to $20 a week to purchase medium size fish (0 to .91 kg live fish, on average). Freshness and appearance (bright, free of bruises, healthy fish) were the most important attributes. Findings indicate that promotion of live fish sales should be targeted to those stores dominated by East Asian (Chinese, Korean, and Japanese) customers.     

Effect of different types of descaling methods on shelf life of air-/vacuum-packaged common carp (<Emphasis Type="Italic">Cyprinus carpio</Emphasis> L.) fillets under refrigerated storage conditions

Microbiological quality, sensory attributes and consumer preferences of common carp (Cyprinus carpio L.) fillets descaled by four different methods under two storage conditions (air packed and vacuum packaged) and refrigerated storage conditions were studied. Farmed common carps (scaly and mirror), of marketable size (2.2 kg, 3 years old), were randomly divided into four experimental groups (n = 10), and filleted and fillets were processed by four descaling methods: without skin, without scales, undercut scales and mirror carp (without any other treatment). Microbiological analyses were determined by total viable counts (TVCs) in logarithm of colony-forming units per gram (log CFU/g), and sensory quality of fillets was classified by odour, flavour, after taste and consistency on storage days 0, 3, 6 and 9. Vacuum packaging conditions affected the growth of microbiota and extended the shelf life of fillets in all experimental groups. Microbial communities grew to between 3.19–3.90, 4.03–6.00 and 6.35–8.28 log CFU/g after 3, 6 and 9 days of storage, respectively, and fillets without skin showed the lowest TVC among all analysed groups throughout storage. Also sensory analyses showed that consistency and odour of carp fillets were influenced by packaging conditions as well as descaling methods. The survey on consumer preferences of carp found out that 58.9 % of customers preferred scaly carp with undercut scales and processed to fillets instead of mirror carp. The results of present study show that different types of descaling methods combined with air/vacuum packaging can significantly prolong the shelf life of carp fillets.     

Determination of the optimal feeding rate and light regime conditions in juvenile burbot, Lota lota (L.), under intensive aquaculture

The aim of the study was to optimize burbot juveniles rearing in recirculating aquaculture system. In experiment 1 (17 °C, photoperiod 24L:0D), the fish (initial: body weight [W] = 15.36 ± 3.72 g, standard length [SL] = 12.48 ± 1.09 cm) were divided into four groups (I, II, III and IV). Different feeding levels were applied: 1, 2, 3 and 4 % of biomass daily (counted based on dry feed weight). The feed conversion ratio (FCR) and specific growth rate (SGR) were recorded. In experiment 2 (17 °C, feeding level of 2 % of biomass day^?1), fish (W = 5.24 ± 2.43 g and SL = 8.54 ± 1.24 cm) were divided into two groups where different light conditions were applied (I: 24 h light [1,800 lx] and II: 24 h darkness [4 lx]). In experiment 1, the highest SGR was recorded in group II (1.93 % day^?1), whereas the lowest SGR (1.27 % day^?1) and final W (P < 0.05) was in I group. The lowest (P < 0.05) FCR (0.63) was in group II. In the remaining groups, FCR was similar (0.68–0.70, P > 0.05). The feed consumption in group I reached 100 %, in group II, it was 71.3 % (P < 0.05) and it was the lowest in groups III (39.26 %) and IV (36.93 %). In experiment 2 no differences in the growth and survival rate were recorded (final SL between 14.16 and 14.19 cm, P > 0.05; W between 23.33–23.35 g; P > 0.05). The results from experiment 1 indicate that the feeding 2 % of biomass day^?1 was the most efficient. Also, it was proven, for the first time, that there was no effect of using different constant light conditions.     

Growth performance and feed utilization of Haliotis tuberculata coccinea (Reeve) juveniles from the Azores (north-eastern Atlantic Ocean): An assay of three mono algae diets

We assessed the dietary value of available seaweeds (Ulva lactuca, Ulva intestinalis, and Sargassum vulgare) as food for juvenile abalone Haliotis tuberculata coccinea. During the 6 weeks that the experiment lasted, initial shell length and weight increased from 13.95 ± 0.32 mm to 15.30 ± 0.30 mm and from 0.39 ± 0.02 g to 0.47 ± 0.03 g. Ulva lactuca diet resulted in higher shell growth rate (58.47 ± 16.76 μm day^?1), SGR (1.15 ± 0.47%.day^?1), weight gain (65.5% ± 33.3), and PER (1.56 ± 0.31), possibly thanks to its higher crude protein content. Both green algae (U. lactuca, U. intestinalis) prove to support the growth of H. tuberculata coccinea. However, they might not be appropriate for an optimal intensive aquaculture production; further research should be conducted to find more efficient diets for juvenile abalone.     

Food selection of burbot (Lota lota L.) larvae reared in illuminated net cages in mesotrophic Lake Maróz (north-eastern Poland)

Feeding and food selection of burbot (Lota lota L.) larvae reared in illuminated cages were studied. The experiment was carried out in mesotrophic Lake Maróz, in north-eastern Poland, for 6 weeks in two successive years. The initial stocking density was 1,250 larvae (20 DPH) per cage. Food selection according to the zooplankton groups (Rotifera, Cladocera and Copepoda) and length classes was expressed by the Strauss linear selectivity index (L). Zooplankton species composition in the lake was similar in the two seasons of the study and organisms shorter than 0.5 mm prevailed in the plankton. The mean number of prey found in burbot alimentary tracts increased from about 40 up to over 200 during the course of the study. A very large inter-individual variation in the amount of food organisms consumed by fish was noted. Analysis of the values of the Strauss food selectivity index shows that at the beginning of the first year of the experiment, burbot larvae preferred copepods, most numerous in the environment at that time; later, fish tended to select cladocerans. In the second year of the study, fish more often ate copepods, irrespective of their quantities in the environment. During the whole study, reared burbot larvae did not eat rotifers, even when they were numerous in cages. Similarly to the rotifers, the smallest planktonic organisms, measuring up to 0.5 mm in length, were typically neglected by fish, while the 0.6–1.0 mm group was most frequently selected. There were also considerable individual differences between particular burbot specimens in their food preferences.     

MARINE FISH PRODUCTION AND MARKETING FOR A CHINESE FOOD MARKET: A TRANSACTION COST PERSPECTIVE

ABSTRACT

From a transaction cost perspective, this paper shows how the tradition of consuming marine fish by the majority of Hong Kong's Chinese citizens has shaped the means and modes of marketing seafood in Hong Kong. It is argued that consumer preferences stimulate aquaculture as a non-open access measure to bypass state fish marketing regulations. This has resulted in two outcomes. First, the transaction cost savings on metering output quantity and quality under private property have led not only to the collapse of the state monopoly on marine fish marketing, but also to the emergence of the (then new but) currently popular kind of Chinese seafood restaurant in Hong Kong. Second, consumer preferences for variety have shaped the form of coordination between the producer and the consumer. The advantage of market coordination has led to the emergence of a system of wholesaling and retailing rather than vertical integration. Issues concerning the emergence of Hong Kong as a regional live marine fish production and trading centre are discussed in terms of the contribution of local mariculture to sustainable development.     

Rearing river lamprey <Emphasis Type="Italic">Lampetra fluviatilis</Emphasis> (L.) larvae under controlled conditions as a tool for restitution of endangered populations

A method for actively protecting river lamprey and increasing the number of river lamprey populations is presented as protocol of rearing stocking material. The objective of the study was to accommodate lamprey larvae during the most critical life period under controlled conditions until they reach a sufficient size, which will increase their chances to survive in the natural environment. The eggs obtained from wild breeders were incubated in Weiss’s jars at the water temperature of 12 °C. The larvae were reared in tanks set up in closed recirculating aquaculture systems. During the rearing period, the water temperature was 20 °C and the density of larvae was 150 individuals per 1 dm² of bottom. In the initial rearing phase, the main focus was on the type of feeds and the nourishment method. It was determined that the most suitable feed type was Artemia nauplii combined with Hikari dry food. Additionally, the type of substrate was tested under controlled conditions. In this case, the optimum one was composed of sand of the grain size between 0.3 and 0.5 mm. The experiment proved that it is possible to successfully conduct river lamprey larvae rearing under controlled conditions. The growth rates are comparable to or better than those achieved under natural conditions. After 30 days of the rearing period, the lamprey larvae were 25 mm long. The results create a possibility to develop a technology for the restitution of river lamprey and other lamprey species, which are endangered throughout the world.     

Effect of time-restricted feeding and refeeding regimes on compensatory growth,body composition,and feed utilization in prawn (Macrobrachium rosenbergii) culture system

ABSTRACT

A 14-week feeding experiment was conducted to determine the effect of a time-restricted feeding and refeeding regime on compensatory growth, body composition, and feed utilization in improved traditional prawn (Macrobrachium rosenbergii) culture systems. Three groups of prawn were used in which the control group (C) received feed regularly at ad libitum and the other two groups, Treatment 1 (T₁) and Treatment 2 (T₂), consumed feed 4 and 5 days per week respectively throughout the first 9 weeks. After feeding restriction, satiation of feed was given in the last 5 weeks. At the end of the experiment, the final weight of prawn in C, T₁, and T₂ were found to be 17.23 ± 6.56g, 16.04 ± 6.18g, and 15.64 ± 6.34 g respectively, which was insignificant. FCR decreased with increased restriction of feeding, while PER and NPU increased. Moisture content increased significantly, while protein and lipid content decreased significantly with increasing restriction time of feeding. After the satiation period, only the T2 group was able to replenish the lipid content. Water quality parameters didn’t vary significantly among the experimental groups and remained within optimum level. Therefore, time restriction could be applied in Macrobrachium rosenbergii culture without detrimental effects on growth, feed efficiency, and nutrient utilization.     

A respirometer system to measure critical and recovery oxygen tensions of fish under simulated diurnal fluctuations in dissolved oxygen

We describe a computer-operated recirculating respirometer system (ca. 140 L water) with six respirometer chambers and a reference chamber (L × W × H: 26 cm × 12 cm × 20 cm; volume 6.24 L) that simulates diurnal dissolved oxygen (DO) fluctuations normally occur in aquaculture ponds. A gas-mixing device, “Digamat” proportionately dissolves gaseous nitrogen and oxygen (and if desired, carbon dioxide) in water to achieve DO levels from 1.0 to 40.0 kPa (0.3–14.0 mg L^?1) at different temperatures. A series of computer-operated valves sequentially allow water from respirometer chambers to a single oxygen probe to measure DO concentration. Oxygen consumptions of fish as the differences in DO concentrations between respirometer and reference chamber are used to calculate different metabolic rates (standard, routine, and active), and critical (P _c) and recovery (P _r) oxygen tensions of individually reared unfed and fed fish. An experiment was conducted to evaluate the ability of the system to measure metabolic parameters for individually reared Nile tilapia (Oreochromis niloticus L.) at three temperatures (low: 22.5, optimum: 27.5 and high: 33.5 °C). The fed fish had significantly higher P _c and P _r values at optimum and high temperatures than unfed fish. At low and high temperatures, both fed and unfed fish had higher P _c and P _r than at optimum temperature. The standard metabolic rate was significantly higher at higher temperatures (44.9, 51.7, and 77.7 mg O₂ kg^?0.8 h^?1 at 22.5, 27.5, and 33.5 °C, respectively).     

Effects of biofilms as the main and as a supplementary food on the survival,somatic growth and gonad enhancement of sea urchin Strongylocentrotus intermedius

Cultured sea urchins of similar size (mean ± SE = 4.33 ± 0.48 g in body weight) were fed biofilms only, kelp (Laminaria japonica)+biofilms (biofilms as supplementary food) and a control diet of kelp only for 7 months in the laboratory. The somatic growth and the survival rate of the sea urchins were measured monthly, and the gonad wet weight and gonad color difference were determined at the end of the experiment. The results show that diet did not significantly affect survival rate (P > 0.05), but had highly significant effects on somatic growth from the first month to the end of the experiment (P < 0.01). Sea urchins fed biofilms only showed negligible or even negative somatic growth at the end of the experiment. Sea urchins on the kelp+biofilms grazed biofilms and consumed kelp during the experiment, and showed sustained greater increase in body weight than those of fed kelp only after the fourth month (P < 0.05). The biofilms may have supplied micronutrients. At the end of the experiment, gonad production of sea urchins fed biofilms was too little (0.11 ± 0.09 g) to identify sex and measure color. Gonad wet weights of males and females and gonad color fed kelp+biofilms did not differ significantly from those of fed kelp only (P > 0.05). However, sea urchins fed kelp+biofilms were more uniform in gonad color than those fed kelp only (P < 0.01), indicating biofilms supplementation could reduce the percentage of low-grade roe. This study therefore reveals the potential of biofilms as a supplementary food in the culture of sea urchins.     

Measurement of Morphometric Dimensions and Mechanical Properties of Rohu Fish for Design of Processing Machines

Indian major carps (IMC) viz. rohu, catla, and mrigal are the most important fresh water species. They are marketed locally without post-harvest processing and value addition because of the lack of suitable processing machines. The present study was undertaken to measure the morphometric and mechanical properties of rohu fish for the development of fish processing machinery, and the same can be adjusted for the other IMC. Twenty-five samples of rohu fish (Labeo rohita) were caught, with weight ranging from 290 to 2,100 g (harvestable size). The measured morphometric dimensions were the body depth (10.14 ± 1.63 cm), thickness (5.9 ± 0.85 cm), head length (9.35 ± 1.04 cm), standard length (37.54 ± 4.17 cm), total length (45.89 ± 5.68 cm), and fish backbone thickness (11.2 ± 4.91 mm). Mechanical properties including the angle of repose over steel surface (20°–22°) and plastic surface (18°–20°) were recorded. The maximum power consumption for slicing the fish lengthwise was recorded as 460 W. The measured morphometric and mechanical properties are useful in limiting the adjustments, design of conveyors, capacity, and power requirement of fish processing machines for rohu fish.     

Design and practical test of a compact phosphorus elimination module for freshwater RAS discharge water

Recirculating aquaculture systems (RAS) can emit total phosphorus (TP) concentrations in their discharge water, which exceed environmentally tolerated restrictions. A compact phosphorus (P) elimination module has been developed and its performance has been tested using the discharge water from a commercial scale freshwater RAS for pike perch (Sander lucioperca) production. To enable its widespread and easy use in practical conditions, the standard principle of chemical-physical phosphorus elimination was adapted to the conditions prevalent in RAS operations. The effect of different precipitants and flocculants in RAS discharge water was studied in laboratory trials. When it came to the TP-elimination performance and the environmental impact, the combination of iron(III) chloride and calcium hydroxide proved highly suitable as the precipitation and flocculation agents. Based on the results that were obtained, a commercial scale P-elimination module was designed. The module was equipped with a 500-L hopper-bottomed reaction tank, dosing units for the precipitation and flocculation agents and valves for the automatic discharge of sludge and cleared water. The TP-elimination potential in different operational modes and retention times was examined. The amounts of excess sludge and cleared water quality were evaluated. The designed 500 L P-elimination module works in automatic batch mode and enables operators to eliminate approx. 95% of the phosphorus emissions from the discharge water from a RAS for annual fish production of about 20 to 25 t. It was possible to achieve TP concentrations of below 1 mg L^?1 in the module’s cleared water discharge.     

Improvement in the feeding activity, early growth and survival of Pacific bluefin tuna Thunnus orientalis larvae fed a casein peptide-based microdiet supplemented with inosine monophosphate

Two feeding experiments were conducted to determine the effect of a 5′-inosine monophosphate (IMP)-supplemented casein peptide-based microdiet (MD) on the feeding activity, growth and survival of Pacific bluefin tuna (PBT) larvae. PBT larvae [total length: 14.0 mm (Exp. 1) or 13.3 mm (Exp. 2)] were fed a casein peptide-based MD supplemented with or without 3% IMP for 12 days. As a negative control, a limited number of yolk-sac larvae of spangled emperor Lethrinus nebulosus were fed only for the first 7 days and starved for the next 5 days. A sufficient amount of yolk-sac larvae of spangled emperor was fed in the Exp. 2. All fish in the control group had died by 9 or 10 days after the experiment. Extensive mortality was observed in fish fed the MD. The MD was only found in the stomach contents of PBT fed the MD + IMP. Of the fish fed an IMP-supplemented diet, 50% survived for 12 days after the initiation of both feeding experiments. In addition, significantly higher growth than that observed during the first 7 days was seen in the PBT in the IMP treatment after 12 days of the feeding experiment. These results suggest that the supplementation of casein peptide-based MD with IMP could improve the feeding activity, survival and growth performance of PBT.     

Exploring consumer’s preferences for farmed sea bream

Sea bream (Sparus aurata) production plays a significant part in Italian aquaculture, contributing to almost 18% of national pisciculture sales revenue. In recent years, Italian firms faced higher competition from countries with lower production costs. This prompted responses toward both cost reduction and product differentiation. The objective of this study was to investigate the preferences of Italian consumers for sea bream from fish farms, with a focus on aspects of product differentiation as gleaned from the analysis of the market situation: price, product origin, type and place of fish farming, and, in particular, type of feed. Data were collected with a consumers’ survey using personal interviews conducted on a questionnaire that included a choice experiment. Consumer preferences were analyzed with choice models based on stated preference data. The models made it possible to evaluate the potential of products with different combinations of attributes for which there is currently no market information available. In particular, the country of origin emerged as an important element of consumer choice, and to a lesser degree, organic certification and fish farming in marine cages also play a relevant role and may command a price premium.     

Effect of feeding frequency on growth,feed efficiency and nutrient utilization of juvenile flounder (Platichthys flesus luscus)

An experiment was conducted to determine the effects of optimal feeding frequency on growth performance, feed efficiency, nutrient utilization and body composition in juvenile flounder. Four feeding frequencies of one (F1), two (F2), three (F3) and four (F4) times a day were evaluated as treatments in triplicate for a period of 60 days. Forty-seven hatchery produced juveniles (2.5 ± 0.7 g) were stocked into 160-L rectangular fiberglass tanks and fed with a commercial diet containing 54 % protein to satiation. At the end of the experiment, the final weight of F1, F2, F3 and F4 were 5.06 ± 0.29, 5.91 ± 0.42, 6.24 ± 0.42 and 6.16 ± 0.46 g, respectively. Growth rates and feed consumption were highest in F3 and lowest in F1. Feed conversion ratios ranged between 0.83 ± 0.04 and 0.90 ± 0.03. There were no significant differences in either moisture or ash content of the fish groups. Protein content decreased with increasing feeding frequency, while lipid content partly increased with increasing feeding frequency. Nitrogen intake and lipid intake were significantly higher in fish fed under F3 and F4 treatment, whereas the nitrogen gain decreased and lipid gain increased with increasing feeding frequency. It is concluded that the flounder juveniles can achieve maximum growth performance and better nutrient utilization when they are fed a given ration two times a day. The findings have practical significance toward establishing an appropriate flounder nursery rearing and will directly benefit the nursery operations.