Performance evaluation of different bedding media in aquaponic system for growth and production of okra and tilapia
Abstract
Aquaponics is the marriage of aquaculture and hydroponic technologies. Present research was accomplished to evaluate the relative performance of only gravels (T1), only coconut husk (T2) and mixture of gravels and coconut husk (1:1 in volume) (T3) as media in aquaponic system to grow okra (Abelmoschus esculentus) and tilapia (Oreochromis niloticus). Each treatment had three replications of similar bedding media. Nine food grade plastic containers filled with media and a 180 liter plastic water tank were used to construct the aquaponic system for growing okra and tilapia, respectively. In each bedding container, 4 okra seeds were sown and tilapia with initial length of 13.65 ± 1.88 cm and weight of 46.04 ± 20.93 g were stocked at the rate of 144 fish/m3 in the fish tank. Tilapia were fed twice a day at the rate of 3% for premier month, 2% for next month and 1.5% of body weight for the remaining time. Fish and plants were sampled biweekly during the whole study period. Data analysis revealed that the treatment T3 performed best followed by T1 and T2, respectively in terms of okra plant growth performances with respect to duration of plant growth in different growth stages, plant height, leaf number per plant, leaf area and branch number per plant. Okra production was shown significantly greater (P ≤ 0.05) in the treatment T3 (9.08 ± 1.25 kg/m2 /157 days) pursued by T1 (7.5 ± 1.83 kg/m2 /157 days) and T2 (3.83 ± 2.33 kg/m2 /157 days), respectively. At the termination of the study, the length gain and weight gain of tilapia were 6.64 ± 0.1 cm and 104.76 ± 20.78 g, respectively. Total tilapia yield was recorded 138.80 tons/ha/157 days with 92.3% survival and FCR of 1.96. The water quality parameters and the nutrient concentrations in influent and effluent water remained within suitable ranges for tilapia production as well as the growth of okra. Therefore, the mixture of gravels and coconut husk media showed incentive performance in plant growth and production of okra compared to the individual media and at the same time the tilapia production was also satisfactory.
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Introduction
Fish is one of the utmost-traded food stuffs worldwide. More than half of fish exports by worth generate in developing states. The dietary contribution of fish is more momentous regarding animal proteins. A volume of 150 g of fish supplies about 50– 60 percent of the routine protein demand for a full-aged person (FAO, 2016). Fruit and vegetables are also necessary components of a salubrious diet. Their adequate daily consumption could help avert serious non-communicable maladies (Lock et al., 2005).
In a small developing country with extensive population growth, aquaculture is intensified to meet the demand of fish protein for increasing population. This creates water pollution and depletes the ground water level day by day. Agricultural land is also used for other purposes which cause pressure on natural resources. To keep pace with the growing food demand, farmers use various chemicals to boost up cereal production. These chemicals strike out human health hazards as well as other environmental problems around the world. All of these obstacles can be defeated to an innovative technology like aquaponics. Aquaponics is a viable food growing technology which connects consecutive aquaculture with hydroponics in a symbiotic condition (Azad et al., 2016). The basic principle of aquaponics is that the wastages of the biological system serve as nutrients to the other system and the water is reused through biological filtration (Bethe et al., 2017).
Diversified leafy vegetables and plants are grown in aquaponics. Among them, okra, radish, lettuce, water spinach, Indian spinach, tomato, capsicum, cucumber, cabbage, carrots, mints, Lettuce, herbs etc. are remarkable (Azad et al., 2016). Several thermal water and non-thermal water fish species like tilapia, trout, perch and bass (Diver, 2006) are cultured in the same system. Among different types of aquaponic systems, media based system is the most common style in the world because it requires less management practices and the fewest components. This system is easy to set in the backyard, rooftop or balcony of the houses.
Conclusion
The present experiment has proved that the mixture of gravels and coconut husk media is more suitable for vegetable growth and production than the individual media. The fish growth and production performances are also favorable in the same aquaponics. The system can be used for fish and vegetable production in urban and peri-urban areas. Thus nutrition and food security will be enhanced with minimum environmental pollution. Moreover, the availability and low-cost of bedding materials and suitability of this system provide better opportunities to fulfill the nutritional demand and maximize the use of land and water.