A 10-week feeding experiment was performed to determine the impacts of partial substitution of soybean meal (SB) with pumpkin seed cake (PSC) in Oreochromis niloticus diets on water quality, growth rate, antioxidant capacity, immunity, and carcass composition. One hundred and fifty tilapia fish (average weight, 11.93 ± 0.17 g) were randomly allocated to five diets. The first diet (the basal diet) contained 420 g of SB per kg of feed. The remaining four diets, namely, D1, D2, D3, and D4, had SB partially replaced by PSC at 10%, 20%, 30%, and 40%, respectively. The results revealed that D4 and D1 significantly improved dissolved oxygen levels, while water temperature, pH, total ammonia, and nitrate levels were not significantly affected. Replacing SB with PSC significantly improved specific growth performance indicators and feed conversion compared to the control, with the D4 group showing the best values. Increasing PSC levels decreased serum glucose, aspartate aminotransferase, alanine aminotransferase, cholesterol, and triglyceride levels. In contrast, the D4 group had higher globulin, albumin, total protein, and lysozyme serum levels. Moreover, fish-fed PSC had significantly increased superoxide dismutase, glutathione peroxidase, and catalase activities and significantly decreased malondialdehyde levels. Increasing PSC substitution levels in fish diets increased the ash and crude lipid contents in the bodies of the fish, while crude protein and moisture decreased. In conclusion, replacing SB with PSC in fish diets significantly enhances growth performance, feed conversion, and fish health. Moreover, the findings suggest that PSC can be a promising alternative protein source for sustainable aquaculture practices.

This experiment aimed to appraise growth performance, hematological and immuno-physiological indices of Nile tilapia when fed on diets in which soybeans were partially replaced by Azolla pinnata or Nannochloropsis oculata. A control diet (basic diet) was tested against 6 practical diets (3 diets partially replaced soybean with Azolla pinnata and 3 diets partially replaced soybean with Nannochloropsis oculata at three different percentages (2.5, 5 and 7.5 %) The highest values of growth parameters were recorded in T3 (Azolla 5 %), followed by T4 (Azolla 7.5 %), T5 (Nano 2.5 %), T7 (Nano 7.5 %), T6 (Nano 5 %), T2 (Azolla 2.5 %), and then T1 (negative control). At the end of the experiment, T4 recoded the highest values of Total protein and Globulin while the lowest readings were in T3, Albumin lowest value was in T5 and the highest one accomplished in T2 with a significant differences between all treatments. For the antioxidant parameters, the negative control (T1) recoded the highest MDA value, while had the lowest values of SOD, GPX and Lysozyme. The highest values of (SOD and GPX) accomplished in T6 while the highest value of Lysozyme was recorded in T4. The challenge with A. hydrophila showed that, the highest mortality rate (80 %) was recorded in control, while the lowest one (10 %) was recorded in T3 and T4.

This study investigated the impact of different nitrogen sources on the growth and biochemical composition of two diatom species, Chaetoceros calcitrans and Thalassiosira weissflogii, and evaluated their use as live feed for Litopenaeus vannamei larvae. Diatoms were cultured in a Conway medium supplemented with four nitrogen sources: potassium nitrate (control), urea, ammonium sulfate, and ammonium nitrate. In a separate experiment, white-leg shrimp larvae (300 larvae/L) at stage Nauplius 6 were fed diets consisting of C. calcitrans, T. weissflogii, or a combination of both diatoms under controlled conditions. The results indicated that urea, ammonium nitrate, and ammonium sulfate significantly enhanced the growth and nutrient composition of C. calcitrans and T. weissflogii compared to the control (potassium nitrate). In C. calcitrans, ammonium nitrate significantly increased protein and lipid contents, while carbohydrate levels were the highest in the control. Similarly, urea and ammonium sulfate treatments yielded the highest lipid levels, whereas the control exhibited the lowest. For T. weissflogii, the control achieved the highest cell count on day 4, but ammonium nitrate significantly improved protein and lipid contents while reducing carbohydrate levels. A mixed diet of C. calcitrans and T. weissflogii significantly enhanced growth performance and reduced mortality rates in L. vannamei larvae compared to single-species diets. In conclusion, the findings indicated that ammonium nitrate was an efficient nitrogen source for enhancing diatom growth. Additionally, combining C. calcitrans and T. weissflogii as a diet improved growth and survival of L. vannamei larvae, offering practical implications for aquaculture.

The study investigated the efficiency of adding extracted chitosan from shrimp wastes to enhance water quality, reduce stress and enhance tilapia flesh quality. Water quality parameters showed no significant differences among all treatments in (Dissolved oxygen, Temperature, pH, NO2 and Orthophosphate values). Treatment fish water with chitosan affected some nitrogenous parameters such as NH3 and NO3, where the values were (0.7, 0.6, 0.1 and 0.5 mg / l) for NH3, and (0.62, 0.61, 0.36 and 0.59 mg / l) for NO3, respectively. The lowest value of NH3 and NO3 was recorded in T3 (15 mg / l chitosan) followed by T4 (20 mg / l chitosan), T2 (10 mg / l chitosan) and finally T1 (negative control). Chemical composition of the samples revieled that the adding chitosan to the water improved moisture, protein, fat and increased ash content for fish flesh respectively, followed by control. Physiochemical quality parameters such as pH, acid value, Free amino nitrogen (FAN), Free fatty acids (FFA), total volatile bases nitrogen (TVB-N) and trimethylamine (TMA-N) showed that the addition chitosan reduce the increase in this parameters of the three treatments compared to the control The blood chemistry indices revealed that; T3 had the lowest AST; T4 had the lowest ALT values compared to control and T2, respectively. Despite the variation in Alb, Glob and ALP values among treatments they showed no significance differences. T3 showed the lowest values among all treatments for GLU, CHO, HDL, LDL and TG followed by T4, T2 and control, respectively.

The present study was conducted to evaluate the individual and combined effects of dietary crude protein levels and magnetic water treatment on the growth performance, water quality, body composition, physiological responses, and immunity of Oreochromis niloticus. Using a 3 × 2 factorial design, three levels of dietary crude protein (25%, 30%, and 35%) and two water types (magnetized and non-magnetized) were tested. A total of 180 juvenile tilapia (average initial weight: 4.13 ± 0.004 g) were randomly assigned to six treatment groups and reared for 10 weeks. Results showed that magnetic water treatment significantly improved dissolved oxygen and pH, while reducing ammonia, nitrite, and nitrate concentrations. Growth performance indicators, including final weight, specific growth rate, feed conversion ratio, and average daily gain, were significantly improved by both magnetic water and increased dietary protein. Carcass crude protein content improved with both the higher dietary protein level and magnetic water, while lipid content decreased. Liver and kidney function indicators (AST, ALT, ALP, and urea) were significantly improved by magnetic treatment and higher protein levels. Blood biochemical markers (TP, ALB, and GLO) were elevated, while glucose, cholesterol, and triglycerides were reduced by magnetic water; significant interactions were observed for globulin, triglycerides, and total protein. Antioxidant enzyme activities (SOD, CAT, and GPx) increased, and MDA decreased in response to magnetic water and high-protein diets. Similarly, digestive enzyme activities (lipase, protease, and amylase) and immune parameters (IgM and lysozyme) were significantly improved, with the best values recorded in the 35% protein + magnetic water group. In conclusion, magnetic water treatment and dietary protein level independently and interactively affect the physiological performance and health of Nile tilapia, with the best outcomes obtained at 35% protein under magnetic water conditions.

The present study was carried out to assess the effects of Spirulina platensis as a feed additive to enhance color and immunity of goldfish (C. auratus). Fish (3.5 g) were randomly assigned to eight concrete ponds (8 m3) with three fish / m3 capacity, and they were split into four treatments in two replicates. A commercial diet of 30 % crude protein was fed to fish in the four treatments as follow: the control group received no additive of Spirulina platensis, T1, T2 and T3 received 6, 8 and 10 g S. platensis per kg, respectively. The highest total carotenoids concentration in the skin of C. auratus was in T2 (1.32 ± 0.15 μg g-1). While MDA exhibited a considerable decline, antioxidants SOD, CAT, and GPx showed tremendous increases. At the termination of the feeding study, there was no discernible difference between the control and the investigated treatments concerning lysozyme activity, IGM, ALT, AST, and ALP. This discrepancy might be connected to spirulina's capability to improve fish health. Histological studies support these results, as no negative changes occurred in the cellular composition of liver tissue. Therefore, we conclude that using Spirulina platensis at a rate of 8 g / kg of feed improves the color quality of goldfish and thus increases their price.