Studies on the feeding of Tilapia nilotica in floating cages

Five studies on the feeding of Tilapia nilotica in floating cages were conducted. Stocking densities of 100 to 200 fish per m³ were used. Only commercially available ingredients were used in the feed.Results of the studies showed that diets containing fish meal, fine rice bran and copra meal had significantly better feed conversion ratios than diets with ipil-ipil leaf meal. Diets with 25% fish meal and 10% copra meal were found to be efficient and economical for T. nilotica.Chicken grower mash enriched with fish meal did not significantly differ from a diet consisting of 25% fish meal and 75% fine rice bran. Fish given moist pellets had significantly higher production than fish fed with dry pellets.     

Revue des pratiques d'elevage de poissons en cages dans les eaux continentalesA review of fish cage culture as practised in inland waters

The rearing of fish in cages could greatly contribute to increasing fish production in existing inland waters. Although it presents numerous advantages, its limitations and possible inconveniences must be borne in mind. Well-developed technology is available mainly from the Democratic Republic of Germany, The Netherlands, Japan, the U.S.A., the U.S.S.R. and the Lower Mekong region. Research is currently pursued in numerous other countries, where the use of floating cages in fish culture is becoming increasingly diversified.The most popular fish species used in intensive cultural systems are Cyprinus carpio, Ictalurus punctatus and Salmo gairdneri. In the semi-intensive Asian systems, Barbus spp., Pangasius spp. and murrels are among the favourite cage-reared fishes. Tilapia aurea and Tilapia nilotica have also proved to be well adapted to cage culture. Polyculture is only rarely practised.Floating cages seem to be the best suited for fish culture in most cases. Net cages are the simplest in design and the cheapest to build. The escape of fish, however, always remains an eventuality which might lead to choosing more expensive designs. Maintenance of cages must be regular. For flexibility of exploitation, cages should not be too large. Their location within the water body can play an important role in keeping production high.At high stocking rates, artificial feeding of a well-adapted diet is a necessity. Optimum conversion rates require a well-adjusted daily ration, possibly fractioned. Mechanized feed distribution is to be encouraged as a labour-saving practice. Less intensive systems rely more on locally available wastes, such as trash fish, but the feeding rate then depends mostly on feed prices.Best growth is generally achieved by C. carpio and I. punctatus. Attainable maximum production is as high as 35 kg/m³/month under intensive management. However, generally, production averages from 5 to 30 kg/m³/month for these two species. S. gairdneri is less productive. T. aurea and T. nilotica have both a very good potential. Production in less intensive systems varies greatly according to management practices.     

Control of reproduction of Tilapia nilotica using cage culture

Experiments were conducted to control reproduction of Tilapia nilotica using cage culture compared with growth and reproduction in ponds. Three rearing densities (5, 15, and 45 fish per cage), and three kinds of aquatic plant (Hydrilla sp., Lemna sp., and Chara sp.) were used as feed.Results of the study showed that Tilapia reproduced in both cages and ponds; however, the intensity of reproduction was low. Growth rates of fish reared in cages were higher than those of fish reared in ponds.Lemna sp. as feed gave the best results in terms of growth rate and protein content of fish flesh. There was no interaction between feed and rearing density.     

Growth of Tilapia nilotica in ponds with differing histories of organic fertilization

A series of six 0.04 ha ponds that had received varying rates of organic fertilization during 1976 and 1977 were each stocked with 200 Tilapia nilotica for a 3.5 month period during the 1978 growing season. Slotted feeding floors were placed over five of the six ponds and two growing-finishing hogs were placed on each feeding floor. The sixth pond received neither manure nor supplemental feed. Growth of T. nilotica was most rapid in ponds that had a history of relatively high manuring rates. Condition factors paralleled fish growth. Survival was 75% or more in each of the ponds with no apparent correlation between percent survival and history of manuring. Water quality was similar and acceptable for tilapia in each of the six ponds. The data indicated that a stocking rate of 50 hogs/ha can result in high fish yields; and that the history of a pond's experimental use influences subsequent experimental results.     

Yields of the African catfish,Clarias gariepinus (Burchell), from a low input,homestead, concrete pond

Fingerlings of the African catfish, Clarias gariepinus (Burchell), with a mean initial average weight of 96.2 g per fish were cultured in a dug-in homestead concrete pond, 30.24 m² in four cycles (1981–1984) for a mean average of 302 days. A mean average weight of 418.4 g per fish was obtained at harvest, resulting in an overall net fish yield of 40.3 kg. Homemade ration was used in the investigation and the feed conversion ratio was 2.6 to 1. There was a mean daily increase in individual fish weight of 1.06 g with overall fish survival of 86.4%.     

Effect of stocking density on the growth performance and yield of Nile tilapia [Oreochromis niloticus (L., 1758)] in a cage culture system in Lake Kuriftu,Ethiopia

This research was conducted to investigate the effect of stocking density on the growth performance and yield of Oreochromis niloticus in cage culture in Lake Kuriftu. The treatments had stocking densities of 50 (50F), 100 (100F), 150 (150F), and 200 (200F) fish per m^?3. All treatments were in duplicate. Juveniles with an average weight of 45. 76±0.25 g were stocked in the treatments. The fish were fed a composite mixture of mill sweeping, cotton seed, and Bora food complex at 2% of their body weight twice per day using feeding trays for 150 days in powdered form. The growth performance of O. niloticus was density dependent. The final mean weight of O. niloticus ranged 147.76±0.28–219.71±1.42 g and the mean daily weight gain was 0.69±0.01–1.15±0.02 g day^?1. Fish held in cages with lower density were heavier than the ones held at higher densities, and showed higher weight gain and daily weight gain. The most effective stocking density, in terms of growth parameters, was 50 fish m^?3. The gross yield (4.5–20.55 kg cage^?1) showed a significant difference with increasing stocking density (P<0.05). Moreover, the apparent food conversion ratio (2.48–7.22) was significantly affected by stocking density (P<0.05). However, survival rate was not affected by stocking density (P>0.05). It can be concluded that the most effective stocking densities were at 50 fish m^?3 cage for larger size fish demand in a short period and 200 fish m^?3 for higher gross production with supplementary feed.     

Supplemental feeds containing coffee pulp for rearing Tilapia in Central AmericaAlimento suplementario conteniendo pulpa de café para la crianza de Tilapia en Centro America

A supplementary feed containing 30% coffee pulp was evaluated for use in the culture of Tilapia aurea in El Salvador, Central America. A comparison of the coffee pulp feed with a feed containing all of the same ingredients except coffee pulp was made with T. aurea raised in 1.0-m³ cages suspended in a fertilized earthen pond. Survival was high in all treatments and there was no significant difference in average weight gain between groups of fish receiving the two experimental feeds. Production trials were conducted in 100-m² fish pens and in 0.05-ha earthen ponds. Pen-raised fish receiving coffee pulp feed grew faster throughout the experiment, and total production was approximately twice that in control treatments. Highest production in pens was 1.25 kg/m² per year. Results of production pond trials using T. aurea at 9 000/ha and stocked with the piscivorous Cichlasoma managuense yielded an estimated 3 392 kg/ha per year in fed treatments and 2 049 kg/ha per year in controls. Low feed conversion (1.92) and low feed cost resulted in an increase in net annual earnings of $251.00/ha.     

Effects of predation by largemouth bass in fish production ponds stocked with Tilapia nilotica

Triplicate ponds (0.07 ha) were stocked with either 0, 29, 86, or 143 largemouth bass fingerlings and 9500 Tilapia nilotica fingerlings (90% males) per hectare. Fish were fed a 32% protein ration for 6 months and then harvested. Average weight of largemouth bass declined as their stocking density increased. Average weight and total biomass of originally stocked tilapia increased with increasing predator stocking density. Total yields of tilapia were not different and averaged 4203, 4355, 4583 and 4230 kg/ha, of which recruits accounted for 28, 29, 26 and 8% for the above respective predator densities. Stocking 143 largemouth bass per hectare was an effective means of decreasing recruitment and increasing yields of larger sized male tilapia.     

Effects of stocking density of Labeo rohita on survival, growth and production in cages

Labeo rohita (139.92 ± 0.76 mm/24.33 ± 0.45 g) was reared for 92 days in floating square cages (10 m² area, 1.5 m height) in a pond (2 ha) at six stocking densities (5, 7.5, 10, 15, 20 and 25 fish m^?2) each with 3 replicates. Fish were fed daily once in the morning with rice polish and groundnut oil cake (1:1) in dough form at 3 % of the total body weight. Survival ranged from 96 to 100 % in different stocking densities. Final average body weight, average body weight gain, mean daily body weight gain and SGR decreased (P < 0.05) with increasing stocking density. Conversely, final biomass, biomass gain and FCR increased (P < 0.05) with increasing stocking density. The highest growth rate of fish could be achieved up to 60 days at 5 fish m^?2 and 92 days at other densities. The reduced growth rate at 10–25 fish m^?2 for 60 days of culture indicated that stress is related to size and density of the fish, suggesting that utmost care is required to reduce the stress at high densities. Maximum production and profit was observed at the highest stocking density. Non-lethal levels of water and soil qualities at different sites (cage premises, and 20 and 200 m away from cage area) suggested that cage aquaculture could be done safely covering 0.9 % of pond area. Production of advanced fingerlings in cages was found a viable alternative to their culture in pond.     

Effect of Feeding Frequency, Water Temperature, and Stocking Density on the Growth of Tiger Puffer, Takifugu rubripes

Effects of daily feeding frequency, water temperature, and stocking density on the growth of tiger puffer, Takifugu rubripes, fry were examined to develop effective techniques to produce tiger puffer in a closed recirculation system. Fish of 4, 14, and 180 g in initial body weight were fed commercial pellet diets once to five times a day to apparent satiation each by hand for 8 or 12 wk at 20 C. Daily feeding frequency did not affect the growth of 14‐ and 180‐g‐size fish. However, the daily feed consumption and weight gain of the 4‐g‐size fish fed three and five times daily were significantly higher than those of fish fed once daily (P < 0.05). Fish of 4 and 50 g in initial body weight were reared with the pellet diet at 15–30 C for 8 wk. The weight gain of fish increased with increasing water temperature up to 25 C and decreased drastically at 30 C for both sizes. Similar trends were observed for feed efficiency, although 4‐g fish had highest efficiency at 20 C. Effects of stocking density on growth were examined with fish of 8, 13, and 100 g in initial body weight. Fish were reared with the pellet diet for 8 or 16 wk at 20 C. Fish were placed in floating net cages in the culture tank, and the stocking density was determined based on the total weight of fish and volume of the net cage. Fish of 8 g in body weight grew up to 35–36 g during the 8‐wk rearing period independent of the stocking density of 8, 15, and 31 kg/m³ at the end of rearing. Final biomass per cage reached 32, 60, and 115 kg/m³ for 13‐g‐size fish, and 10, 18, and 35 kg/m³ for 100‐g‐size fish, and the growth of the fish tended to decrease with increasing stocking density for both sizes.     

Productivity and Economics of Nile Tilapia Oreochromis niloticus Cage Culture in South-East Brazil

ABSTRACT

Fish cage culture is an intensive, continuous-flow fish farming system, allowing intensive exploitation of water bodies with relatively low capital investment. This study aimed to determine the production function of Nile tilapia, Oreochromis niloticus, in cages; the profit-maximizing biomass at 300–400 and 500–600 fish per m³ for cages of different volumes; and the influence of water body conditions in fish performance. Feed intake, survival rate, and water temperature were monitored daily; dissolved oxygen, pH, and transparency of water were monitored each 15 days. Caged tilapia were fed daily on commercial, floating pellets (32% crude protein) at 0900, 1300, and 1700, and feeding rate was adjusted based on weight gain and survival rate. Data were analyzed statistically by ANOVA (P = 0.05) and regression analysis; the Mitscherlich function was chosen to represent the production function. Carrying capacity of both stocking densities reached 200 kg/m³ and no differences were found (P > 0.05) regarding accumulated biomass and individual average weight over time. The larger stocking density yielded larger accumulated biomass and had better feeding efficiency and no differences between individual average weights of fish at both densities were observed (P > 0.05). Profit-maximizing biomass at 500–600 fish/m³ was 145 kg/m³ and at 300–400 fish/m³ was 121 kg/m³. Cage farming of Nile tilapia at 500–600 fish/m³, individual average weight 283 g, presented many advantages: optimization of space and production time, better feed efficiency, higher fish production per unit volume of cages, and increased profitability.     

Growout production of camouflage grouper, Epinephelus polyphekadion (Bleeker), in a tank culture system

Growout production of the camouflage grouper, Epinephelus polyphekadion (Bleeker), in a 10-m³-capacity fibreglass tank culture system was evaluated, using hatchery-produced fingerlings (56-59 g initial weight) at stocking densities of five, 15 and 45 fish m^?3. During the first 9 months of a 12-month growout period, the fish were fed twice a day with a moist pellet feed containing 40.9% protein. From month 10 onwards until harvest, the fish were fed moist pellets in the morning and trash fish in the evening at a 1:1 ratio. The final weight of fish at harvest was up to 900 g, with mean weights of 544.6 ± 170.72 g at five fish m^?3, 540.2 ± 150.82 g at 15 fish m-^?3 and 513.3 ± 134.52 g at 45 fish m^?3. The results showed no significant differences (P > 0.05) in growth rate and fish size between the different stocking densities tested. The average daily growth rate ranged from 0.62 to 3.38 g fish^?1 day^?1, with mean weights of 1.49 ± 0.74 g fish^?1 day^?1 at five fish m^?3 through 0.53 to 2.38 g fish^?1 day^?1, 1.32 ± 0.57 g fish^?1 day^?1 at 15 fish m^?3 to 0.48-3.32 g fish^?1 day^?1 and 1.31 g fish^?1 day^?1 at 45 fish m^?3 stocking density. Although up to 100% survival was observed at the lowest stocking density, the survival rate significantly decreased (P < 0.05) with increasing stocking density. The food conversion ratio (FCR) significantly decreased (P <0.05) with increasing stocking densities, showing efficient feed utilization with increasing stocking densities of E. polyphekadion. The FCR averaged 2.1 at a stocking density of 45 fish m^?3. The yield in terms of kg fish produced m^?3 of water used in the culture system significantly increased (P < 0.001) from five to 45 fish m^?3. The yield averaged 17.3 ±0.53 kg m^?3 at a stocking density of 45 fish m^?3. The present results show that the present tank culture system could sustain more biomass in terms of increasing fish stocking densities. The growth performance of E. polyphekadion observed during this investigation has been reviewed with other grouper species.     

Maximum yield approximation and size distribution patterns of stocker size largemouth bass,Micropterus salmoides reared in a semi‐closed indoor system

The main objectives of this study were to approximate the maximum yield and evaluate size dispersion of stocker size largemouth bass, Micropterus salmoides reared in a semi‐closed recirculating system for 60 days. Fingerlings with an average body weight of 36.7 g were utilized for the study. An experimental system consisting of 18 square plastic tanks (165 L) equipped with a radial flow settler, a sump, a moving bed filter, a centrifugal pump, a rapid sand filter, a down‐flow oxygen saturator and a UV sterilizer was utilized for the trial. The system was operated semi‐closed, accounting for a daily exchange rate of 30–50% of total system water volume. Experimental stocking densities were 4.5, 9.1, 18.8, 36.5, 54.6 and 73 kg m^?3 with three replicates per treatment. At the end of the experimental trial, largemouth bass showed acceptable feed conversion (1.00–1.48), specific growth rate (1.16–1.45% day^?1) and survival rate (81.8–96.6%) in all treatments, displaying the highest performance at an initial stocking density range of 18–36 kg m^?3. Based on a piecewise regression model with breakpoint analysis, maximum yield of largemouth bass fingerlings should not exceed 70 kg m^?3. As stocking density increased, relatively more underweight fingerlings were produced with a higher uniformity of fatness.     

Comparative study of growth performance of three strains of Nile tilapia, Oreochromis niloticus, L. at two stocking densities

This study was conducted to investigate the effect of stocking density (125 or 200 fish m^?3) on the growth performance of three strains of the Nile tilapia, Oreochromis niloticus: the non‐improved strain (NS), the genetically improved farmed tilapia (GIFT) and the Freshwater Aquaculture Center selected tilapia known as the FaST selected line (SL). Each strain and density combination was triplicated in 0.42 m³ fibreglass tanks within a re‐circulating water system. Water temperature was maintained at 29.0±1.0°C. Large Nile tilapia having a mean body weight of 100–110 g were stocked in each tank and hand‐fed four times daily with commercial tilapia pellets (35% protein) for 104 days. Results showed that at the two stocking densities, the GIFT and SL strains showed a significantly higher (P<0.05) mean weight (MWT), daily growth rate (DGR), specific growth rate (SGR), feed conversion ratio (FCR) and gross yield (GY) than the NS. In all three strains, growth performance was negatively affected by stocking density. The lower density (125 fish m^?3) treatments had significantly higher MWT, DGR and SGR than the higher density one (200 fish m^?3). However, higher FCR and GY were observed at the higher density. Survival rates were high in all treatments and were not affected by strain or density. In general, the SL strain had better growth parameters than the GIFT strain. The findings of this study demonstrated the superior growth performance of the improved strains at both densities compared with the NS. The higher density (200 fish m^?3) could be more profitable for the tilapia farms in Kuwait than the lower density of (125 fish m^?3) in terms of reduced land cost and facilities, demand on the limited low‐salinity underground water and manpower.     

Recruitment control and production of Tilapia aurea (Steindachner) with the predator,Cichlasoma managuense (Günther)

The effects of different stocking rates and ratios of Tilapia aurea (Steindachner) in combination with Cichlasoma managuense (Günther) on tilapia recruitment and production were evaluated in 440 m² ponds. The research was conducted at the National Fisheries Station in El Salvador, Central America.The tilapia A_T value, the total weight of marketable tilapia (14 cm or larger) expressed as a percentage of the total weight of the whole tilapia population, averaged 96 or greater at a stocking ratio of 4:1 (fingerling tilapia: fingerling C. managuense) and at a stocking ratio of 8:1 (fingerling tilapia: adult C. managuense). Tilapia A_T values at a stocking ratio of 8:1 (fingerling tilapia: fingerling C. managuense) ranged from 71–89.Highest estimated annual production of marketable tilapia (3611 kg ha^?1) occurred at the highest stocking rate of 12000 tilapia ha^?1 in populations with an average tilapia A_T value of 98. Greatest weight gain of marketable tilapia (167 g of 1.17 g day^?1) occurred at the lowest stocking rate of 6000 tilapia ha^?1 in populations with an average tilapia A_T value of 99.Estimated annual production of marketable C. managuense ranged from 212–414 kg ha^?1. The average weight gain of marketable fish varied from 48–60 g (0.32–0.40 g day^?1). The average C. managuense, A_T value was 54, ranging from 29–84.The estimated production of marketable fish of both species at stocking rates of 6000, 9000 and 12000 tilapia ha^?1 in populations with tilapia A_T values of 96 or greater averaged 3295, 3290 and 4025 kg ha^?1 per year, respectively.     

Economic production of estuary grouper, Epinephelus salmoides Maxwell,reared in floating net cages

The factors affecting production of estuary grouper, Epinephelus salmoides, in floating net cages are discussed. The concept of economic production in cage culture is outlined. Economic production of estuary grouper could be achieved by providing a suitable culture site with good water quality; ensuring proper farm management and regular maintenance of cages; preventing disease and ensuring efficient treatment; providing optimum stocking density, a balanced diet, optimal feeding frequency; manipulating fish behaviour by providing artificial hides; and manipulating physiological characteristics, e.g. by the use of growth promoters.The paper futher describes environmental parameters, such as dissolved oxygen content, water temperature, salinity, water current, bacteria count, pH, and bottom sediments, as important factors in site selection. Their effects on the growth and production of fish are discussed and their optimal levels determined. The problems involving management and maintenance of the farm are also outlined. The main problem in cage culture is fouling which demands considerable labour and money for cage maintenance. Other problems such as predators, poaching, and cannibalism are discussed at length. It is suggested that by manipulation of stocking density, production could be increased. The optimal stocking rate was found to be 60 fish/m³ which gives a high yield of marketable fish. Stocking could be further intensified by providing artificial hides using used car tyres. The net production could be increased by 230% if hiding space of 251 cm³ per fish was provided and the stocking density increased to 156 fish/m³. Although formulated feeds enhanced growth by 27.1% over that of groupers fed on trash fish, the production cost was much higher, rendering the use of formulated feeds alone uneconomical for commercial fish culture. Growth promoters such as 17α-methyltestosterone and nitrovin have been found to promote growth of young estuary grouper by 43.4 and 62.8%, respectively.Using various combinations of culture techniques, it was shown that net production could be increased from 23.76 kg/m³ using conventional culture methods to 136.75 kg/m³ with a combination of hiding space, heavy stocking, appropriate feeding frequency and formulated feeds incorporating growth promoters. The production time was also shortened considerably from 6 months to 2.7 months.Cost-benefit analysis of the eight culture techniques tested indicated that the production cost could be reduced from US$2.00/kg with conventional methods to as low as US$1.28/kg using a sophisticated method. However, based on current market proces, the conventional culture technique was still economically feasible, as the net income over total capital costs was 33.3%. Improvements of the conventional culture technique will increase the ratio of net income over total capital costs by 1–3 times.     

Use of artificial hides to increase the stocking density and production of estuary grouper, Epinephelus salmoides Maxwell,reared in floating net cages

The relative growth and production of estuary grouper, Epinephelus salmoides, in response to seven combinations of hiding space and stocking density were studied in floating net cages. Used car tyres were suspended in the net cages to provide hiding space for the fish. The seven combinations of hiding space and stocking density were as follows:

Provision of hiding space in the net cages was found to permit an increase in the stocking density from the optimal rate of 60 fish/m³ (without artificial hides) to 156 fish/m³. The net production was found to increase from 8.5 kg/m³ to 19.5 kg/m³ after 3 months. Growth in terms of weight gain per fish, survival rate and food conversion ratio at stocking rates below 156 fish/m³ with hiding space between 116 and 222 cm³/fish was comparable to that observed at the optimal stocking density without hiding space (60 fish/m³). The growth of fish stocked at 180–204 fish/m³ with hiding space of 272–289 cm³/fish, respectively, was found to be significantly depressed. Thus, with the provision of hiding space of 251 cm³/fish, the stocking density could be increased to as high as 156 fish/m³ and the production of fish could be increased by 230% over that at the usual optimal stocking rate of 60 fish/m³ without artificial hides.     

Influence of feeding regime on intraspecific competition, fin damage and growth in 1+ Atlantic salmon parr (Salmo salar L.) held in freshwater production cages

The feeding behaviour, growth and feed conversion ratio (FCR) of cage‐held Atlantic salmon parr (Salmo salar L.) were studied when in 576 m³ (12 m × 12 m × 4 m) commercial freshwater cages under ambient water temperature (8.84±3.53°C) and photoperiod (11.02±2.05 h) for 205 days. The effect of feeding regime on fin damage was also investigated. Six groups (n=31 234±2051 fish group⁻¹, initial stocking density 1.25±0.14 kg m⁻³) were fed to satiation using either (a) an imposed regime involving scheduled, fixed ration feeding every 10 min from dawn till dusk or (b) on demand from dawn till dusk using commercial interactive feedback systems. During feeding, there were no significant differences in aggression although swimming speeds and turning angles were significantly higher in fish under the imposed regime. On‐demand feeding significantly reduced the incidence of dorsal fin damage. There was no clear relationship between fish size, feed regime and the incidence of fin damage until 1 week before the fish were transferred to marine cages, when the smallest fish under each feeding regime had the highest incidence of fin damage. Interestingly, growth did not differ between regimes, but fish under the imposed regime were significantly overfed and achieved higher FCRs.     

Factors affecting androgen sex reversal of Tilapia aurea

Tilapia aurea were fed a single level of androgen-treated feed (ethynyltestosterone at 60 mg/kg of feed — ET-60) under a variety of conditions to determine the effect on sex reversal. Sex ratios were significantly altered in favor of males in 16- and 19-day treatments at 21 and 30° C; all-male populations were produced in 21- and 28-days at 21° C, but a few females persisted in the groups at 30° C. Feeding regimes of 12% body weight/day and satiation had variable impacts on growth but did not adversely affect success of sex reversal, except at higher temperatures. Because of higher metabolic rate at 30° C and the concomitant increase in appetite, a fixed level of feeding at 12% of body weight was considered to be limiting and was later increased to 15%. High stocking density (2600 fry/m² of surface) reduced growth rate but did not affect sex reversal. A 21-day treatment with ET-60 fed at 15% body weight/day at water temperatures between 21 and 30° C should consistently produce all-male populations of T. aurea at stocking densities up to 2600 fry/m².     

The effect of stocking density on yield,growth, and survival of Asian river catfish (<Emphasis Type="Italic">Pangasius</Emphasis><Emphasis Type="Italic">bocourti</Emphasis> Sauvage, 1880) cultured in cages

Asian river catfish (Pangasius bocourti Sauvage, 1880) were cultured at five different stocking densities in cages (submerged volume 1 m³) suspended in a dugout pond from August to November 2009. Pangasius bocourti fingerlings (mean weight 27.09 ± 0.54 g) were stocked at densities of 12, 25, 50, 100, and 200 fish m⁻³. At the end of 3 months, the harvest weights (gross yields) were, respectively, 2.05 ± 0.30, 5.20 ± 0.31, 10.60 ± 0.42, 19.98 ± 0.78, and 42.37 ± 0.41 kg m⁻³. The mean fish weights among the stocking densities of 25, 50, 100, and 200 fish m⁻³ were not significantly different, but were significantly higher than that of the 12 fish m⁻³ density. The specific growth rates among high stocking densities of 50, 100, and 200 fish m⁻³ were not significantly different; however, they were significantly higher than those of the low stocking densities of 12 and 25 fish m⁻³. Asian river catfish performed poorly at the lowest density. The results indicate an initial lower stocking threshold for Asian river catfish of above 5.20 kg m⁻³. The Asian river catfish cultured in small cages placed in a pond reached the desirable market size (>200 g) within a 90-day grow-out period. The results show that the maximum yield for Asian river catfish during a 3-month production cycle was not reached.