The formulator of aquatic diets is part of a continuous search for alternative protein sources instead of depreciated fish meal. The utilization of zooplankton as a feed ingredient is an interesting trend due to their high-quality protein content and abundance of essential nutrients. The current study aims to investigate the effects of partial and total replacement of fish meal (FM) by Dahpnia magna meal (DMM) on growth performance, feed utilization, histological, and economic status of mullet, M. cephalus, larvae. In addition to the control diet, 100% FM, D0, four diets containing DMM at different levels were used: 25% (D25), 50% (D50), 75% (D75), and 100% (D100) replacement of fish meal. A total of 300 larvae (0.097 ± 0.001 g) were equally divided into five groups (three replicate per each group) at a density of 200 larvae m−3. The aquariums were renewed at a rate of 30% daily. During the 60-day experimental period, all larvae were fed their respective diets at a level of 20% of live body weight, five times a day (9.00 a.m., 12.00, 15.00, 18.00, and 21.00 p.m.). The results indicated that compared to D0, fish fed D75 recorded the highest significant value of growth, and feed utilization parameters, while fish fed D100 achieved the lowest feed cost and incidence cost, and the highest profit index and economic efficiency ratio. A strong correlation was reported among weight gain, feed conversion ratio and fish meal replacement with DMM; R2 = 0.94 and 0.91, respectively. The fit regression model representing mullet response to FM replacement with DMM is a poly-nominal regression model with maximum response at 75–100%. The histological investigation of the intestine revealed an improvement of histomorphometric indices and goblet cell number with increasing DMM inclusion levels. These findings confirmed that 75% to 100% partial substitution of FM with DMM is the ideal replacement for mullet, M. cephalus, larvae for improving fish growth performance and feed utilization.

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The objective of the current study was to evaluate the growth performance, survival, feed utilization, whole body composition and biochemical blood parameters of Nile tilapia, Oreochromis niloticus and thinlip mullet, Liza ramada, fed diets supplemented with four levels of lemon peel (0, 0.5, 1 and 2%) in a polyculture system. The fish were stocked in 2×5×1 m concrete tanks at a density of 40 Nile tilapia (0.6 g) and 10 thinlip mullet (3.3 g) fingerlings per tank and were fed a pelleted diet (~25% Crude protein), twice daily for 77 days. Treatment with 2% lemon peel had significant positive effects on growth, feed utilization and total biomass of Nile tilapia, whereas 0.5% lemon peel was optimal for thinlip mullet. The blood parameter results showed thatNile tilapia fed 2% dietary lemon peel had the lowest triglyceride, amylase and glucose levels. In contrast, thinlip mullet fed 0.5% dietary lemon peel had the highest levels of amylase and glucose compared with the other groups.

Fishmeal is the most expensive feedstuff in the aquafeed and one of the most environmentally limiting factor of aquaculture development. Therefore, the search for alternative protein sources is a continuous process. The present feeding trial was conducted to evaluate the effects of replacing fishmeal with zooplankton biomass meal (ZBM) on the growth performance, nutrient utilization, intestine, and liver histological changes of grey mullet, Mugil cephalus (initial weight of 0.10 ± 0.01 g). Five isoproteic (35% crude protein) and isolipidic (8% crude lipid) diets were formulated as the control diet (Z0) and the other four diets (Z25, Z50, Z75, and Z100), where 25%, 50%, 75%, and 100% of fishmeal was replaced by ZBM, respectively. After 60 days of feeding, the final weight, weight gain, and daily growth index of the grey mullet fed the Z100 diet were higher than those fed the control diet (p < 0.05). In addition, the better values of feed conversion ratio, protein efficiency ratio and lipid efficiency ratio were recorded in the fish fed with the Z100 diet. Additionally, the intestinal villus length, crypts depth, and muscle thickness were significantly improved with ZBM inclusion (p < 0.05). Meanwhile, there were no histopathological changes observed on the liver when compared with the control group. From the economic point of view, dietary substitution of fishmeal by ZBM (Z100) reduced the cost of diet formulation by 18% and the price per kg weight gain by about 40%. Overall, according to the findings of this study, substituting fishmeal with ZBM up to 100% could improve growth performance, feed utilization, gut health status, and profit ability of rearing M. cephalus juveniles.

The future of aquaculture development is directed toward high intensification to overcome the decline in natural fishing and to provide enough protein for the increasing world population. The spread of aquaculture production and intensification requires the search for high-quality, new efficient feed ingredients with low cost and sustainable importance. Therefore, the current study aimed to detect the effects of partial or total replacement of fishmeal with amphipod meal, Gammarus pulex, on growth performance, survival percent, feed utilization, histological alteration of intestine and liver, and economic yield of grey mullet, Mugil cephalus, fry. Five diets were formulated to contain 100% fishmeal (FM), or FM replaced with 25%, 50%, 75%, or 100% amphipod meal (APM) (D0, D25, D50, D75, and D100, respectively). A total of 300 grey mullet fry (0.097 ± 0.001 g), were divided into five groups (three replicates each) at an initial stocking density of 20 fry per aquaria (100 L). The aquarium’s water is renewed at a rate of 30% daily. During a 60-day experimental period, the feeding rate was 20% of body weight, which was introduced as five meals per day. Fish fed D50 achieved the highest significant values of final weight (1.80 g), weight gain (1.70 g), survival (86.67%), final length (4.47 cm), and length gain (2.06 cm). In addition, the feed utilization of diets containing increasing substitution levels of FM showed that the highest protein intake (0.82 g ish−1), protein efficiency ratio (0.83), protein productive value (30.65%), and the lowest significant feed conversion ratio (1.21) were recorded with D50. The dose-response study revealed that the best substitution levels could range between 50% and 75%. Histological observations confirmed that the highest number of goblet cells and intestinal villi were recorded in the group fed D50. No pathological effect was observed in the liver at all substitution levels. In terms of economic efficiency, the best economic conversion ratio was recorded in the group fed D50. This study confirmed that 50% partial substitution of FM with APM is the ideal replacement level for grey mullet fry. In addition, the use of a new renewable alternative, such as APM to substitute FM, could relieve the pressure on the capture of wild fish and reduce the environmental impact of inland aquaculture.

The research is target to study the effects of pond soil types (sand and clay) and initial body weight of Mugil capito fingerlings on their growth performance, survival, production and profitability. It was used in the rearing poly-culture system of Nile tilapia (Oreochromis niloticus) with carp's species (common, silver and grass carps). Water quality results revealed that the T °C, salinity, pH ammonia and DO for SSP and CSP were in the appropriate limits Moreover, the water quality in CSP was better in quality and quantity of phytoplankton and zooplankton, were total numbers of phytoplankton community and zooplankton populations were higher in water samples collected from CSP stocked with M.capito SIW comparing with those collected from SSP, while the highest value recorded in CSP stocked with LIW. Fish performance parameters revealed that the final fish body weight, individual weight gain, average daily gain, specific growth rate, survival percentage and fish production were better in CSP than SSP. Moreover, results detected that the all growth parameter were the highest in CSP under stocking LIW of M.capito than SIW. The evaluation economic efficiency showed that CSP achieved the best revenue and the best growth and production performances. It can be concluded that, the all ponds are economically profitable and the revenue could cover the costs of production, but the LIW M.capito culture in CSP possessed the best economical profitability parameters than SIW fish culture in CSP and SSP.

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The cDNa sequence of Bestrophin-1 (BEST-1) was identified from a previously constructed transcriptome data set of freshwater prawn Macrobrachium rosenbergii (Mr).Basal and temporal gene expression analysis of MrBEST-1 showed its antimicrobial immune effectiveness during viral and bacterial infections. The protein sequence encoded by cDNA of MrBEST-1 was examined and a short antimicrobial molecule, named WP17 was identified using a bioinformatics tool. Further, the antibacterial ability of the identified WP17 peptide was evaluated against a number of bacterial strains, in which the peptide showed potential bactericidal activity against Micrococcus luteus (MTCC 6164), Staphylococcus aureus (ATCC 9144), Escherichia coli (ATCC 9637), Klebsiella pneumonia (CI 7376) and Bacillus subtilis (ATCC 6051). Based on the results, further assays focused on M. luteus MTCC 6164. The mode of action of MrWP17 on M. luteus MTCC 6164 was analyzed using FACS and FESEM. Toxicity analysis suggested that WP17 impaired the viability of cells in murine melanoma cells (B16F10); however, no cytotoxicity was observed against kidney embryonic cells (HEK293), even at higher concentrations. Similarly, the gene expression analysis of WP17 peptide treated murine cells elicited an extrinsic apoptotic pathway. In the present study, we have demonstrated the involvement of MrBEST-1 in immune mechanisms through its short peptide molecule that has potential antimicrobial activity.