The present study aimed to investigate the effects of Moringa oleifera leaf (MLE) extract-supplemented diets on the growth, feed utilization, hematology, innate immune response, and disease resistance of Nile tilapia against Streptococcus agalactiae Biotype 2. Four hundred and fifty Nile tilapia (32.61 ± 0.2 g/fish) were randomly allocated into fifteen tanks (30 fish/tank). Different concentrations of MLE at 0%, 0.5%, 1%, 1.5%, and 2% were fed to the Nile tilapia for 30 days, and the growth, feed utilization, hematology, and innate immune response of the Nile tilapia were determined. After the feeding trial, the Nile tilapia were challenged with a S. agalactiae Biotype 2 infection, and the relative percentage of survival (RPS) was determined. Results revealed the presence of quercetin, kaempferol, and p-coumaric acid in the MLE extract, exhibiting stronger antimicrobial activity against S. agalactiae Biotype 2. The diets supplemented with the MLE-0.5 group showed a significantly higher growth, feed utilization, hematology, and innate immune response in the Nile tilapia compared to the control and other MLE groups. Additionally, the MLE-0.5 group exhibited a significantly higher RPS of the Nile tilapia against S. agalactiae Biotype 2. Therefore, MLE-0.5 can be employed as an alternative feed supplement in sustainable Nile tilapia farming to protect against S. agalactiae Biotype 2.

During the last few decades, aquaculture as a useful animal protein providing sector intensifies to meet the growing world population demands. Although fish culture technological advancement has resulted in increased production, intensive technology has negatively affected the environment—consequently, aquaculture research efforts have been diverted towards developing sustainable culture technology. Introducing algae and bacteria singly or in combination in aquaculture was advantageous both by ex-vivo and in-vivo culture techniques. Utilization of microbial consortium in aquaculture can help to construct three pillars (social, economical, and ecological) of sustainability by improving water quality, reducing dependency on a wild fish stock as a feed ingredient, improving the health status of animals, and increasing economic returns along with protection of the environment. Numerous fruitful research outcomes on using algal-bacterial systems are available for its application in aquaculture. In this context, the present article highlights an updated review of current research trends on various aspects such as application of algal-bacterial consortia for aquaculture, available technologies based on their interaction, and recommendations for further improvement. This review will also provide some critical clues for the standardization of novel fish culture techniques based on microbial interaction.

A seed rearing experiment was attempted to evaluate the effects of stocking densities in the biofilm‐based system reared with pearlspot, Etroplus suratensis on different aquaculture parameters. Pearlspot advanced fry of size (4.67 ± 0.04 cm/1.71 ± 0.03 g) stocked at four different stocking densities viz 50 fish (T₁); 100 fish (T₂); 150 fish (T₃) and 200 fish (T₄) m⁻³ in the biofilm‐based rearing system and at the rate of 150 fish m⁻³ in the clear water fed (CWF) system tanks. The total ammonia nitrogen and dissolved oxygen levels in biofilm tanks with different stocking density were significantly lower than CWF. Diatom was found as dominant plankton in all biofilm treatment tanks in water as well as on substrate. The growth parameters were found to significantly decrease with increasing stocking density in the biofilm‐based rearing system. The significant highest individual growth parameters and significantly lowest fish biomass were found in T₁. Final fish biomass was found to increase with increasing stocking density up to 150 advanced fry m⁻³ and then reduced due to decreased survival. Body composition analysis of E. suratensis showed increased protein and decreased lipid levels in all biofilm‐based rearing system treatments at different stocking densities compared with clear water fed system. The present investigation findings on plankton abundance, growth, body composition and blood parameters at different stocking densities will provide guidelines for selecting appropriate stocking density for pearlspot advanced fry to fingerling rearing in a low saline biofilm‐based system without providing a supplementary diet.

The present study on the effect of green water system with harvested rain water on growth performance of freshwater fish Catla catla. Spawn of Catla with an initial length 5.50±0.04 mm and weight 10.99±0.30 mg were stocked at the rate of 6, 8, 10 and 12 no.l-1 in cement tanks (2x1x1m). The green water system containing live phytoplankton viz., Chlorophyta, Cyanophyta and zooplankton viz., Rotifera, Cladocera, Copepoda and Protozoa were was used. The results of the study indicated that the maximum average length gain was (357.89±3.08%), weight gain (779.53±18.03%), specific growth rate (5.56±0.08%) and survival (45.20±0.13%) and were recorded significantly (P<0.05) at stocking density of 6 spawn l-1 as compared to the other stocking densities. The growth of spawn to fry was observed to decrease with increase in the stocking density. Observations on the water quality revealed that the dissolved oxygen value decreased with an increased stocking density. Whereas, the value of ammonia-nitrogen, nitrite-nitrogen, and nitrate-nitrogen increased with the increase in the stocking density. The study showed that better growth and survival of Catla catla spawn to fry stage with stocking density of 6 spawn l-1 reared for a period of16 days in cement tank. The overall results of this study indicated that green water system with harvested rain water has a potential for rearing fish seeds.

Aim: Biofilm-based aquaculture systems, proven cost-effective, reduce the need for expensive supplementary feed. The biofilm acts as a natural planktonic food source for reared organisms. Previous research highlighted the influence of fish stocking density and biomass on plankton diversity in different aquaculture settings, underscoring the significance of these factors in biofilm-based systems. Hence, the present study attempted to understand how varying stocking densities of pearlspot (Etroplus suratensis) influence plankton diversity indices in the biofilm-based aquaculture system. Methodology: The present experiment was designed in 5 Practical Salinity Unit (PSU) brackishwater with soil-bottomed FRP circular (500 L) tanks for 60 days. The sugarcane bagasse was used as a substrate forbiofilm production after fertilization with cow dung, urea, and lime. Fries of pearlspot (4.67 ± 0.04 mm 1.71 ± 0.03 g-1) were stocked at four different stocking densities in triplicates viz T1 (50 nos); T2 (100 nos), T3 (150 nos) and T4 (200 nos) fish fry m-3 in the biofilm-based rearing system. Plankton samples were collected from water and biofilm deposited on the substrate and analyzed for diversity indices. The Shannon Diversity Index, Simpson Diversity Index, Simpson Dominance Index, and Margalef Richness Index were used to compute the plankton diversity indices in different treatments using standard equations. Results: In the current investigation, lower stocking densities with lower fish biomass were associated with significantly higher (P≤0.05) Shannon Diversity Index, Simpson Diversity Index, and Margalef Richness Index in water. In contrast, the Simpson Dominance Index in water showed a significantly lower (P≤0.05) value for treatments with lower fish biomass than for treatments with higher biomass. Interpretation: The values obtained for various diversity indices indicated that a biofilm-rearing system with lower E. suratensis biomass produced more planktonic abundance, evenness, and species richness. Key words: Biofilm, Pearlspot, Plankton diversity, Stocking density