Aquaculture technology using Recirculating Aquaculture System (RAS) is basically a technology for fish farming by reusing water used in production. This technology is based on the use of mechanical and biological filters, and this method in principle can be used for all species cultivated in aquaculture such as fish, shrimp, shellfish and others. This study was carried out at Station for Investigation of Fish Health and Environment (LP2IL) Serang’s field test facility starting from June to November 2020 (110 days of sand lobster grow-out period). In this study, the RAS system used for grow-out of sand lobster uses a series of containers, compartments, tanks and equipment for water treatment with the following purification stages (1) sedimentation containers; (2) physical filtration; (3) biological filtration, (4) disinfection of water by UV irradiation, (5) removal of CO2, (6) clean water reservoirs and (7) tanks for grow-out of sand lobster. In this study, a series of tests were carried out on several biological activities parameters of sand lobster including growth weight and length, FCR, SR, molting and biomass, which were measured every two weeks during grow-out period. From the results of this study activity, it is found that the biological parameters of sand lobster grow-out with RAS is improving when compared to sand lobster grow-out in flow through water system (FT).
Aquaculture with the Recirculation Aquaculture System (RAS) is a unique engineered ecosystem that minimizes environmental disturbances by reducing the discharge of nutrient pollution through reuse of water used in fish farming. This activity was conducted at LP2IL Serang field test facility starting in June-November 2020. In this test, the RAS system used for growing of sand lobster uses the stages of purification: sedimentation, physical filtration, biological filtration, water disinfection with UV irradiation, removal of CO2, clean water reservoirs and sand lobster rearing tanks. Water quality parameters tested: a) physics: DO, pH, temperature and salinity are measured every day; b) chemistry: ammonia (TAN and UIA), nitrite, nitrate and phosphate are measured every two weeks. If from the UIA value calculation, the value is above the quality standard (> 0.05 mg / L) then added molasses (26.02% organic C) with a concentration of 64 gr / gr TAN; c) microbiology: total bacteria and Vibrio sp. counting. From the results of this study it is known that RAS can maintain stable water quality for a relatively long time. High availability of organic matter (from leftover feed, feces and addition of molasses) can promote the growth of nitrifying bacteria. The "maturation" of the nitrifying bacteria in the biofilter compartment takes about 6 weeks. These bacteria are able to reduce levels of ammonium nitrogen, where the accumulation of nitrate nitrogen (NO3-) which is produced from the overhaul of nitrite nitrogen (NO2-) by nitrifying bacteria, is a signal that the maturation process of nitrifying bacteria has been achieved. The nitrification process consumes alkalis, hence lowers the pH value in the water, besides it also consumes a large amount of oxygen. The low number of bacteria and vibrio in the RAS system was affected by the use of a UV-sterilizer with a wavelength of 254 nm.
Pathogenic bacterial namely Streptococcus sp has widely spreads in Seabass culture, particularly in fingerlings. It might caused decreasing production quality and quantity. To improve this problem, a study have been done to feed the seabass by using the combination of immunostimulan and antibiotics. The parameter observed were the survival rate and growth rate. Juveniles of 2 cm in size with Streptococcus symptoms were reared in 6 units of 2 m 3 tanks with stocking density of 5,000 fishes per tank. They were fed with artificial feeds mixed by immune stimulant and antibiotics (5gr/kg and 2gr/kg, respectively). The experiment was done with 3 replicates and one control for 20 days. The results showed that the survival rates were significantly different between A and B (control) with 20.2% (3,030 ind) and 12.5% (1,875 ind), respectively. There were no significant different in the growth rates between A and B with body length 5.90 cm and 5.80 cm, respectively.
Abstrak. Kegiatan perekayasaan ini dilakukan untuk mengetahui efektifitas penggunaan "The Redfield Ratio Calculator" dalam penghitungan jumlah pupuk nitrogen dan phosphat yang diaplikasikan pada media budidaya udang vaname untuk mempertahankan keseimbangan nilai N/P rasio agar keseimbangan dan kehidupan plankton di media budidaya udang dapat dipertahankan. Penelitian ini dilakukan pada bulan Mei -September 2017 di tambak udang milik Balai Layanan Usaha Produksi Perikanan Budidaya (BLUPPB) Karawang. Dalam studi ini dipergunakan "The Redfield Ratio Calculator" untuk penghitungan jumlah pupuk nitrogen dan phosphat untuk mempertahankan keseimbangan N/P rasio sebesar 20-30 dibanding 1 untuk pertumbuhan terbaik bagi diatom di dalam media budidaya. Caranya dengan memasukkan nilai nitrat dan phosphat dari hasil pengukuran air tambak ke dalam kalkulator tersebut sehingga didapatkan nilai Buddendorf rasio, kemudian dikali 1,53 untuk mendapatkan N/P (Redfield) rasio sebenarnya. Hasil studi menunjukkan bahwa penggunaan "The Redfield Ratio Calculator" sangat memudahkan untuk mempertahankan N/P rasio yang ditunjukkan dengan stabilnya N/P rasio pada kisaran 20-30 : 1. Nilai N/P rasio ini menyebabkan pertumbuhan alga hijau secara normal dan jumlahnya tidak melampaui jumlah ideal untuk kehidupan udang vaname di tambak. Pemanfaatan metode ini juga dapat meningkatkan performa (berat dan panjang), hasil panen (biomassa) serta mencegah terjadinya serangan penyakit pada udang vaname.
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