Growth and Survival of Juvenile Lined Seahorse (Hippocampus erectus) at Different Food Densities

To investigate the effect of Artemia nauplii with different densities on the survival and growth of Hippocampus erectus juveniles,newly hatched H.erectus juveniles were fed with Artemia nauplii for 50 days,which were divided into three groups [5 nauplii/mL(A),10 nauplii/mL(B) and 20 nauplii/mL(C)].The results show that the survival and growth of juveniles could not be explained by three food densities during the first 10 days.The survival of juveniles with 10 nauplii/mL and 20 nauplii/mL food densities were significantly higher than that with 5 nauplii/mL from day 20 to day 50(P0.05),but there was no significant difference found between the survival in treatments B and C.Additionally,the weight and height of juveniles in treatments B and C were significantly higher than that in treatment A on day 20(P0.05).The weight and height of juveniles in treatments A and C increased dramatically than that in treatment B from day 30(P0.05),and the difference in growth among the three food densities groups reduced on day 40,then the weight and height of juveniles in treatment A was higher than those in treatments B and C(P0.05).The weight gain(WG),condition factor(CF) and special growth rates(SGR) of the juveniles with three food densities were not significantly different on day 50.The pH and DO of water decreased with increasing of food density over 24 h,however,water quality was not deteriorated to become a major factor reducing the growth of the juveniles.Furthermore,the concentration of ammonia-N in treatment C was significantly higher than that in treatments