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Dwarf gourami (Trichogater lalius) is a sexually dimorphic fish, a male of which is traded twice the price of a female in Sri Lankan ornamental fish industry. Thus, the present study was conducted to obtain the optimum concentration of 17α-Methyltestosterone for sex reversal of T. lalius female through immersion treatment in order to obtain all male population. Immersion treatment with 17α-Methyltestosterone concentrations of 750 μgLˉ¹, 1,000 μgLˉ¹, 1.250 μgLˉ¹ and 1,500 μgLˉ¹ were used for 3 h period at third, fifth and eight day after hatching. The control was without hormone treatment. The experiment was conducted for 150 days period after hatching. Gourami immersed in 1,500 μgLˉ¹ and 1,250 μgLˉ¹ hormone concentrations produced significantly higher percentage male populations of 93.6 % and 87.9, respectively. The survival rates of 1.500 μgLˉ¹, 1,250 μgLˉ¹, 1,000 μgLˉ¹, 750 μgLˉ¹ and the control treatments were 16.7 %, 50.6 %. 63.3 %, 68.3 % and 83.9 %, respectively. Therefore, the most suitable concentration of 17α-Methyltestosterone for sex reversal of T. lalius was recognized to be 1,000 μgLˉ¹. However, the study need further evaluation on the effect of 17α-Methyltestosterone on sex reversal process and fine changes of concentrations to achieve 100 % sex reversal of T. lalius with higher survival rate.
Dwarf gourami (Trichogater lalius) is a sexually dimorphic fish, a male of which is traded twice the price of a female in Sri Lankan ornamental fish industry. Thus, the present study was conducted to obtain the optimum concentration of 17α-Methyltestosterone for sex reversal of T. lalius female through immersion treatment in order to obtain all male population. Immersion treatment with 17α-Methyltestosterone concentrations of 750 μgLˉ¹, 1,000 μgLˉ¹, 1.250 μgLˉ¹ and 1,500 μgLˉ¹ were used for 3 h period at third, fifth and eight day after hatching. The control was without hormone treatment. The experiment was conducted for 150 days period after hatching. Gourami immersed in 1,500 μgLˉ¹ and 1,250 μgLˉ¹ hormone concentrations produced significantly higher percentage male populations of 93.6 % and 87.9, respectively. The survival rates of 1.500 μgLˉ¹, 1,250 μgLˉ¹, 1,000 μgLˉ¹, 750 μgLˉ¹ and the control treatments were 16.7 %, 50.6 %. 63.3 %, 68.3 % and 83.9 %, respectively. Therefore, the most suitable concentration of 17α-Methyltestosterone for sex reversal of T. lalius was recognized to be 1,000 μgLˉ¹. However, the study need further evaluation on the effect of 17α-Methyltestosterone on sex reversal process and fine changes of concentrations to achieve 100 % sex reversal of T. lalius with higher survival rate.
Sri Lankan mud crabs, with their growing demand in local and international markets as a geographically indented delicious food product. The demand driven processing of mud crabs also drives the pollution of water and land because of greater accumulation of crab shells at the processing plants and their improper disposal. The present study was designed to divert shells from waste to value chain. In this study chitosan were chemically extracted from Scylla serrate (Sri Lankan mud crab) shell waste using microwave irradiation. The processes were optimized using simplex-centroid design with triplicates. Independent variables for process steps demineralization (DM), deproteinization (DP) and deacetylation (DA)were concentration of hydrochloric acid (cHCl) for DM and sodium hydroxide (cNaOH) for DP and DA, time (Tirr) of irradiation and solids to liquid ratio (S/L).Variables ash removed (Arem), nitrogen removed (Nrem) and degree of deacetylation (DDA) were measured as response variables. Statistica 13.3 software was used to analyze the results for best fit model, standard effects of treatments at a significance of p<0.05 and optimal process conditions....
