The growth and development of healthy culture subjects are essential in increasing productivity in the aquaculture industry. A primary determinant of aquatic animal productivity is the ambient microbial population. If an aquatic animal's microbiome is diverse, with bacteria favoring beneficial over pathogenic species, the health and growth of the animal (i.e., fish or crustacean) can be substantially improved. Embryonic and newly hatched Zebrafish Danio rerio larvae were reared in the presence of (1) water from the broodstock culture tank as a control, (2) a probiotic solution containing 19 strains of live lactic acid bacteria (LAB), or (3) an antibiotic (AB) solution with amoxycillin. Developmental parameters were monitored until 10 d postfertilization. Bacteria present in the water and larvae were cultured and identified by sequencing the V4 hypervariable region of bacterial 16S ribosomal RNA. Probiotic‐treated larvae showed significant increases in every measured morphological parameter and in survival compared to the controls and AB‐treated larvae, including TL, eye development, and swim bladder development before first feeding. Staining with DASPEI (2‐(4‐[dimethylamino]styryl)‐N‐ethylpyridinium iodide) produced fluorescence, revealing increased mitochondrial activity in the gastrointestinal tracts of probiotic‐treated larvae and reflecting advancement of initial metabolic function. Probiotic‐treated larvae showed accelerated yolk absorption, resulting in increased nutrient mobilization and growth. Microbial analyses revealed a greater concentration of bacteria in larvae in response to the probiotic treatment compared to the other two treatments. Species identified in all three treatments included Pseudomonas spp. and Aeromonas spp. (Proteobacteria). The second most diverse and abundant microbiome was seen in controls, whereas AB‐treated larvae had the least diverse microbiome. All treatments revealed the presence of proteobacteria, but an AB‐resistant pathogenic bacterium (Stenotrophomonas maltophilia) was identified in the AB group. These results reveal that the presence of LAB and other bacteria favorably influenced early larval growth, development, digestive function, and survival in Zebrafish even before the onset of feeding.

A light environment in aquatic habitat is one of the essential physical parameters affecting the growth and physiology of fish. To investigate the effects of light on the growth of zebrafish embryos and larvae (Danio rerio), fishes were reared under the illumination of Light Emitting Diodes (LEDs) of different wavelengths, including green, red, blue, and white. Morphometric, neuromast staining with 2-[4-(Dimethylamino)styryl]-1-ethylpyridinium iodide (DASPEI) and Polymerase Chain Reaction (PCR) analyses were used to examine the initial development of sensory capacity in this study. On days 5, 6, and 7, the green light produced the most favorable result. Blue light consistently impacted early parameters such as eye development, egg yolk absorption, and total length. These impacts were synchronous with the initiation of feeding. Exposure to specific wavelengths of light can induce the appearance of gene expression, opn1lw1 detected opsin and (mtnr1ba and aanat2) were active under all four experimental lighting conditions. This retinal gene appears to be sensitive to ambient wavelength, but apparently, genes in the melatonin pathway are not.

Microbial diversity within an aquatic community can be used to increase the growth and development of organisms. In this study, Zebrafish larvae were reared in three treatments 1) a probiotic containing 17 strains of Lactobacillus spp., 2) an amoxicillin solution, 3) water from the broodstock culture tank as the control. Survival of the larvae throughout 10 dpf was recorded. To determine the development of the gastrointestinal tract DASPEI stain was used for larvae at the age of 3 dpf to 6dpf. The intensity of the fluorescence in each larva was observed through the automated digital microscope. According to the experiment results, a significant difference (P<0.0001) in the survival rates among all treatments was recorded. The probiotic-treated larvae (PTL) had a higher survival rate. This could be due to the presence of lactic acid bacteria in the probiotic treatment, which helps in enhancing immunity. In DASPEI staining, also PTL exhibits more fluorescence in the GI tract at 24 hours to 48 hours post-hatch than the other two treatments. The main possible reason behind this could also be the presence of Lactobacillus spp. Which directly influences the higher activity of the digestive system.

Tofu is a common food in Indonesia, made from soybean, and needs gigantic water for the process. The liquid waste of the tofu industry is usually directly discharged into the river without being processed. Liquid wastes of tofu have high organic content and become a problem in water pollution. Rotating Biological Contactor (RBC) is efficient method to treat waste with a high organic matter load by utilizing microorganisms to consume organic matter through biofilms. Biofilm will degrade organic matter aerobically. The purpose of the study is to determine the capability of RBC to reduce the organic content of tofu wastewater with different rotations of the disk. Rotation was experimentally varied from 30, 40, 50, 60 RPM and control. Results were considered in percentage decrease from the untreated waste: TSS of 87.56 ± 6.48%, BOD of 99.13 ± 0.21 %, and COD of 98.53 ± 0.08%. To conclude, the optimum rotation is 50 RPM for decreasing BOD and COD, otherwise 40 RPM for reducing TSS. The results effluent RBC on three parameters passed the quality standards legally for the soybean processing company or activity.