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Abdul Qayyum Siddiqui Yousef S. Al-Hafedh Ahmed H. Al-Harbi Seikh A. Ali 《Journal of the World Aquaculture Society》1997,28(1):106-112
Abstract This study was conducted to evaluate the effects of stocking density and monosex culture on growth, survival, yield and feed conversion ratio of freshwater prawn Macrobrachium rosenbergii in concrete tanks. Juvenile prawns with an average weight of 1.8 g were stocked into triplicate tanks at densities of 5, 10, 15 and 20 prawns/m2 , grown for 168 d and fed a 34% tilapia diet. Stocking density had significant effect on prawns. Final mean body weight decreased with the increasing density, being highest at 5 prawns/m2 (29.6 9). and lowest at 20 prawns/m2 (17.4 g). Total yield increased from 135 g/m2 (1,350 kg/ha) at a density of 5 prawns/m2 to 261 g/m2 (2,610 kg/ha) at density 15/mz to 245 g/m2 (2,450 kg/ha) at 20/mz . Feed conversion ratios were high and ranged from 3.7 (5 prawns/m2 ) to 5.6 (20 prawns/m2 ).
In monosex culture of freshwater prawns stocked in triplicate tanks at a density of 5 prawns/m2 for 112 d, the all-male population had the best growth performance and feed conversion ratio, followed by the mixed-sex and all-female populations. The all-male population had 99% marketable prawns (>20 g) with an average yield of 159 g/m2 (1,590 kg/ha); the mixed-sex population had 90% marketable prawns and the yield was 135 g/mz (1,350 kg/ha); and the all-female population had 75% marketable prawns with an average yield of 108 g/m2 (1,080 kgha). 相似文献
In monosex culture of freshwater prawns stocked in triplicate tanks at a density of 5 prawns/m
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Yousef S. Al-Hafedh Aftab Alam Mohamed Salaheldin Beltagi 《Journal of the World Aquaculture Society》2008,39(4):510-520
An indoor aquaponic system (i.e., the integration of fish culture with hydroponic plant production in a recirculating setup) was operated for maximizing water reuse and year-round intensive food production (Nile tilapia, Oreochromis niloticus , and leaf lettuce) at different fish feed to plants ratios. The system consisted of a fish culture component, solid removal component, and hydroponic component comprising six long channels with floating styrofoam rafts for holding plants. Fish culture effluents flowed by gravity from the fish culture component to the solid removal component and then to the hydroponic component. Effluents were collected in a sump from which a 1-horsepower in-line pump recirculated the water back to the fish culture tanks at a rate of about 250 L/min. The hydroponic component performed as biofilter and effectively managed the water quality. Fish production was staggered to harvest one of the four fish tanks at regular intervals when fish attained a minimum weight of 250 g. Out of the total eight harvests in 13 mo, net fish production per harvest averaged 33.5 kg/m3 of water with an overall water consumption of 320 L/kg of fish produced along with the production of leaf lettuce at 42 heads/m2 of hydroponic surface area. Only 1.4% of the total system water was added daily to compensate the evaporation and transpiration losses. A ratio of 56 g fish feed/m2 of hydroponic surface effectively controlled nutrient buildup in the effluents. However, plant density could be decreased from 42 to 25–30 plants/m2 to produce a better quality lettuce. 相似文献
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Effect of dietary protein level on the reproductive performance of Nile tilapia, Oreochromis niloticus (L.) 总被引：1，自引：0，他引：1
The effects of five dietary protein levels (25%, 30%, 35%, 40% and 45%) on the individual spawning frequency and the egg production of 135 tagged female Nile tilapia, Oreochromis niloticus (L.), were studied from 8 May to 19 November 1996 in outdoor concrete tanks. Virtually identical spawning patterns were found in all treatments, but there was a great deal of variation in the frequency of spawning and egg production. Overall, individual spawning frequency varied from one to 14 and individual egg production from 31 to 2828 eggs per spawning. The average number of spawnings and average number of eggs per spawning for fish receiving dietary protein levels of 25%, 30%, 35%, 40% and 45% were 8.0 ±1.6, 8.4 ± 2.2, 8.5 ± 2.7, 8.4 ± 2.5 and 9.4 ± 2.1 spawnings, and 1167 ± 305, 1082 ± 410, 1288 ± 324, 1145 ± 389 and 1328 ± 311 eggs per spawning, respectively. Fish receiving 45% dietary protein spawned more frequently than fish receiving 25% dietary protein. The total number of eggs produced per female was significantly higher for females fed 45% protein feed than females receiving 25% and 30% protein feeds. No definite trend was found in the number of eggs produced per spawning and the number of eggs produced per gram in females fed at different protein levels. Based on weekly checking, the time interval between spawnings varied from 7 to 77 days, and mean spawning intervals ranged from 15.8 to 17.1 days. Sixty per cent of females spawned after an interval 14 days, 15% after 21 days, 13.6% after 7 days, 7.2% after 28 days, 1.8% after 35 days and 1.0% after 42 days, and the time interval was 49-77 days for the rest of the females (1.5%). In all treatments, maximum spawning activity was recorded from May to August, and thereafter, it gradually decreased and no spawning females were found in November. 相似文献
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Isonitrogenous and isocaloric diets (32% protein, 4.3 Kcal/g) were formulated to replace fishmeal by single cell protein (SCP) from two yeasts, Saccharomyces cerevisiae and Candida utilis, grown on date (Phoenix dactylifera) processing waste in diets for two size groups (avg 15.39 g and 25.14 g) of juvenile Nile tilapia (Oreochromis niloticus). A control diet (T1) with fishmeal and six experimental diets (S1, S2, and S3 with S. cerevisiae, and C1, C2, and C3 with C. utilis) each containing 11.6%, 23.2%, and 34.2% yeast as SCP were prepared to replace 25%, 50%, and 75% of fishmeal, respectively. Tilapia fed on the control and experimental diets (S1, S2, C1, C2) with 25% and 50% replacement of fishmeal showed better growth and feed utilization. Fish fed on diets S3 and C3 (75% fishmeal replacement) had significantly (p < 0.05) poorer growth suggesting that yeast SCP can replace up to 50% of fishmeal in juvenile tilapia diets. 相似文献
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Three kinds of locally available plastic biofilter media with different configurations (plastic rolls, PVC pipes and scrub pads) were evaluated for their efficiency in organic waste removal from the effluents of an intensive recirculating tilapia culture system. A set of three types of solid-removing filters consisting of screened sedimentation; upflow sand as well as plastic bead filtration accomplished the mechanical filtration. Values of critical metabolic wastes like total ammonia nitrogen (TAN) (0.92 ppm) and nitrite-nitrogen (NO2-N) (0.22 ppm) were found to be well within the acceptable limits, while other water quality parameters in the culture water were also maintained within the normal range by the filtration system. Removal rates of 3.46 g TAN/m3 per day and 0.77 g NO2-N/m3 per day, as well as TAN and NO2-N removal efficiencies of 29.37 and 27.3% respectively, were established to be the best for the plastic-roll biofilter medium as compared to PVC-pipe and scrub-pad media. Percent removal of TAN and NO2-N per pass of the biofilter (25.49 and 26.3% respectively) and the specific TAN and NO2-N removal rates (43 and 9.6 mg/m2 per day) of plastic rolls were also found to be superior to the other two biofilter media. Pieces of PVC pipes as biofilter medium is recommended to be used in the biofilters in view of their cheaper cost. 相似文献
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The effects of four levels of food supply (0.5%, 1%, 2% and 3% body weight daily) were investigated on some reproductive traits and growth of hybrid tilapia in outdoor concrete tanks. Fast-growing fish matured early in the season (March), but spawning started late in May. Smallest size of males and females at first maturity was 8.1 cm. Fish size at maturity appears to be influenced by the feeding level, which affects the growth of fish. For both sexes, no significant difference was found in gonadosomatic index (GSI) among different treatments. Mean percentage of mature fish decreased with decreasing food supply and was found to be significantly different between fishes fed at 3% (46%) and 0.5% (28%) body weight. Fecundity increased with increased feeding levels, although significant differences were found only between 3% and other feeding rates (0.5–2.0%). The fecundity per g female was higher at the lower ration levels (0.5% and 1%) than at the higher feeding levels. Egg quality, with respect to egg size, hatchability. fry length and weight, was not affected by the feeding rates. Final mean weight and food conversion ratios were significantly influenced by feeding rates. Higher increase in ovary weight with increasing body weight of mature females fed at 0.5% body weight than fishes receiving higher food levels suggests that in these fish, more food resources are diverted towards gonad building than to somatic growth. 相似文献
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