Effect of different feed types and rearing densities on survival rate and growth performance of mud clam larvae(Geloina coaxans)

Abstract

The study is aimed to investigate suitable feed and stocking density in larvae rearing process to obtain the high survival rate. The experiment 1 included four food treatments as (i) 100% fresh algae (Nanno chloropsis sp and Chaetoceros sp with 1:1 ratio), (ii) 100% dry algae (Spirulina powder), (iii) 75% fresh algae + 25% dry algae, (iv) 50% fresh algae +50% dry algae. Larvae in each treatment cultured in 5L-bottles. Stocking density was 2000 larvae/L. Experiment period was from D-larvae to 12th – 15th days when observed that larvae metamorphosed to umbo stage and began transfer to spat. Experiment 2 included three treatments as (i) 2000 larvae/L, (ii) 4000 larvae/L, (iii) 8000 larvae/L. Kind of food had the best result from experiment 1 was applied for feeding in experiment 2. The best result in experiment 1 was treatment used 100% fresh algae. Length and width of larvae reach highest with 217.3µm and 230µm on day 17, respectively. Otherwise, metamorphosis rate of larvae was 31.2% and survival rate of mud clam larvae reached 10.5% on day 17.Larvae production reached 300individuals/L. In experiment 2, the best result was treatment rearing with 2000 individuals/L. Length and width of larvae reach highest with 218.3µm and 231.3µm on day 17, respectively. Otherwise, metamorphosis rate of mud clam larvae was 34.9% and survival rate of mud clam larvae reached 10.3% on day 17. Larvae production at treatment 2000 larvae/L was the highest in all treatment with 294 individuals/L.