Effects of stocking density on the growth,feeding and aquaculture water environment of Hyphessobrycon rosaceus
To investigate the effects of stocking density on the growth,feeding,and water quality of Hyphessobrycon rosaceus,individuals with an average body weight of(0.63±0.17)g and an average body length of(29.41±2.23)mm were placed in aquariums with seven different stocking densities(D1-D7):1 500,2 250,3 000,3 750,4 500,5 250,and 6 000 fish/m3,with a trial period of 30 days,during which growth and water quality indicators were observed.The results showed as follows:The survival rates of H.rosaceus in groups D6 and D7 fell below 60%on days 12 and 9,respectively,leading to the termination of those groups.At the end of the experiments,the survival rate of group D5 was(97.78±1.11)%,while all other groups had a survival rate of 100%.After 30 days of culture,the weight gain rate[WGR,(59.91±16.79)%]and specific growth rate[SGR,(1.55±0.35)%/d]of group D2 were significantly higher than those of the other groups(P<0.05),while the SGR of group D5[(0.36±0.09)%/d]was the lowest.With the increase of stocking density,the feed conversion ratio(FCR)initially decreased and then increased,with the lowest FCR(1.96±0.55)in group D2,and the highest FCR(10.17±2.64)in group D5,significantly higher than in other groups(P<0.05).At the end of the experiment,the concentration of ammonia nitrogen increased with stocking density,while nitrite nitrogen first decreased and then increased.The accumulated nitrate-nitrogen concentration in group D5[(33.95±4.61)mg/L]was significantly higher than other groups at the end of the experiment(P<0.05),while the accumulated nitrate nitrogen content was the lowest in group D2[(13.66±4.14)mg/L].The study indicated that stocking density significantly affected the growth performance,feeding status,and water quality of H.rosaceus,with the optimal stocking density being D2(2 250 fish/m3).The regression equation for body length(L)and body weight(W)at the optimal stocking density is WD2=1.61×10-5×LD23.13(R2=0.78).
Hyphessobrycon rosaceusstocking densitygrowthfeed intakeaquaculture water environment
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