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Growth, production and biofiltration rates of seaweed, Ulva lactuca were investigated at two stocking densities (3 kg and 6 kg m−2) and two effluent flow rates (5.4 and 10.8 m3 day−1) to optimize an integrated mariculture system at Saudi Red Sea coast. effluents from fish-rearing tank, stocked with 200 kg fish (Oreochromis spilurus), fed to six seaweed tanks via sedimentation tank. Fish growth (weight gain 1.75 g fish day−1), net production (NP, 10.16 kg m−3) and survival (94.24%) were within acceptable limits. Ulva showed significantly higher (F = 62.62, d.f. 3, 35; P

Seaweeds absorb inorganic nutrient wastes from mariculture and reduce their undesirable environmental effects. Mariculture in Saudi Arabia is increasing rapidly, thus, to exploit aquaculture wastes and to reduce coastal pollution risks, local seaweeds were cultured using mariculture effluents in integration on the Red Sea coast. The aim of the present study was to test integrated aquaculture of seaweed and marine fish (Oreochromis spilurus) for the first time in Saudi Arabia and to determine the seaweeds, Ulva lactuca and Gracilaria arcuata, biomass production and inorganic nutrient bioremediation capabilities. Results showed that G. arcuata grew at a significantly higher rate (2.71% wet weight day−1) than U. lactuca (1.77% wet weight day−1). The biomass yield (42.38 g wet weight m−2 day−1) and net yield (91.11 g wet weight day−1) of G. arcuata were also significantly higher than U. lactuca (27.39 g wet weight m−2 day−1 and 58.89 g wet weight day−1, respectively). Gracilaria arcuata removed 0.45 g m−2 day−1 of total ammonia nitrogen (TAN) with 80.15% removal efficiency and 1.03 g m−2 day−1 of soluble phosphate with 41.06% efficiency. Ulva lactuca removed 0.42 g m−2 day−1 of TAN with 83.06% removal efficiency and 1.07 g m−2 day−1 of soluble phosphate with 41.11% efficiency. Total tissue carbon of both species reached 25.1–26.9% and nitrogen content reached 3.0–3.2% of dry weight. The C/N ratio for both seaweeds was

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.

Isocaloric diets with 25,30, 35,40, and 45% protein levels were fed to triplicate groups of juvenile (1.96 ± 0.2 g) freshwater prawn, Macrobrachium rosenbergii, at 3% to 6% body weight per day for 168 days. No significant effect of dietary protein level on weight gain, specific growth rate, and survival was found (P > 0.05). Highest wet weight gain was recorded for prawns fed 35% protein diet and the poorest for prawn fed 25% and 45% protein diet. Protein efficiency ratio (PER) progressively and significantly (P < 0.05) decreased with increasing level of dietary protein. The results of the present study suggest that dietary protein requirement of freshwater prawn is 35%.

Recirculating greenwater aquaculture technology is an appropriate method for producing commercial quantities of tilapia in locations that have water scarcity. Greenwater systems achieve three major goals; higher fish production, maximum water recycling (> 98%) and nutrient utilization. Some nutrients are recycled back in this system to sustain the development of photosynthetic algae and nitrifying bacteria creating a “suspended growth treatment process” that maintains adequate water quality. In this study, the greenwater system was implemented in triplicate, each replicate had a fiberglass fish culture tank and a cone bottomed clarifier for solid filtration. Water from the fish culture tanks is pumped to the cone clarifier through the airlift and the outflows of the cone clarifiers trickled back to the fish culture tanks at a rate of 7–8 L/minute. The study was designed to compare the performance of a greenwater system with mixed-sex, as well as, all-male tilapia. Culture tanks were stocked at a ...

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).