The use of two enrichment forms (Brachionus plicatilis enrichment and rearing water enrichment) with probiotic bacilli spore on growth and survival of Silver carp (Hypophthalmichthys molitrix)

This study was carried out to evaluate the effect of probiotic (Bacillus latrospores and Bacillus licheniformis) on growth and survival of Silver carp larvae (Hypophthalmichthys molitrix). Rotifers (Brachionus plicatilis) were used as live prey vehicle for probiotic transport. They were cultured in sea water with 15 ppt salinity and Nannochloropsis oculata microalgae was used as feed. Five treatments were prepared with three replicates (four experimental treatments and one control). Silver carp larvae were obtained from a local fish farm (Golestan، Iran). Rotifers were filtered from intensive cultivation tanks with 200 rotifer/ml density and then transferred to conical glasses for the enrichment process، and were kept under enrichment conditions for 24 h. Two forms of enrichment were carried out: rotifer biocapsulation and rearing water enrichment. T1 and T2 were fed with biocapsulated rotifers and T3 and T4 were fed non-biocapsulated rotifers. Instead of biocapsulation، the same density of bacteria was injected directly into the rearing water of T3 and T4. T3 (4. 4 ± 1. 2 mg) and T4 (5. 05 ± 1. 95 mg) treatments of probiotic injected water had significantly higher growth rates than T1 (2. 21 ± 0. 94 mg) and T2 (3. 9 ± 0. 36 mg)، (P<0. 05). T1 (3. 9 ± 1. 03 mg) and T2 (3. 3 ± 0. 36 mg) had higher growth rates than the control (2. 21 ± 0. 94 mg) and were also significantly different from each other (P<0. 05).