Growth and survival of giant gourami juvenile immerse indifferent frequencies using recombinant growth hormone

This study was aimed to determine the immersion frequency of recombinant growth hormone (rGH) in the growth stimulation of giant gourami juvenile. A total of 50 larvae at second day after first feeding, was immersed in 30 ppt salt water for 2 minutes, and then transferred into 200 mL of 9 ppt salt water containing 30 mg/L rGH in inclusion bodies form. Immersion was performed for 60 minutes and repeated once a week for two, three, four, and five weeks. As the control, fish was immersed with inclusion bodies without rGH (control-1), bovine serum albumin (control-2), 9ppt saline water without rGH (control-3) and in freshwater (control-4). Fish were kept in 7L aquaria during the first four weeks, transferred into 50L aquaria for two weeks, and then in hapa (2×1×1 m3 in size) for two weeks. The results showed that the highest (p<0.05) average body weight of giant gourami juvenile (2.23±0.19 g) was obtained at four times (four weeks) immersion treatment. Similar body weight of fish in two times (1.72±0.29 g), three times (1.68±0.34 g), and five times (1.81±0.17 g) immersion was obtained. Fish body weight of all controls was lower than the rGH-immersed fish. Average body weight of four time rGH-immersed fish (4.01 g) remained higher than other treatment and control (1.96 to 2.36 g) on 8th week of fish rearing. Survival of four times (96.67±1.15%), and five times rGH-immersion fish (95.33±4.16%) was similar, and higher than other treatments and controls (77.33 to 89.33%). Thus, higher growth rate and survival of giant gourami juvenile could be achieved by four times rGH immersion. Keywords: recombinant protein, growth hormone, immersion frequency, giant gouram