BACKGROUND: The use of natural immune stimulants is one of the most effective methods for strengthening immunity and preventing diseases in fish. OBJECTIVES: Due to the abundance of red algae (Laurencia caspica) in the Caspian Sea, the aim of this study was to investigate the effect of this algae on growth performance and blood indices of rainbow trout. METHODS: The present study was performed on 750 randomly selected rainbow trout (Oncorhynchus mykiss) in 5 experimental treatments including an algal extract-free diet (control), and diets supplemented with 0.5, 1, 1.5, and 2% of algal hydroalcoholic extract. During the experimental period, fish were sampled to measure growth performance and blood indices every two week for 8 weeks. RESULTS: Growth indices were not affected by the algal extract at the end of eight weeks of feeding. There were no significant differences in fish survival at different treatments. Total counts of red blood cells, white blood cells, hematocrit percentage, hemoglobin concentration and neutrophil and monocyte percentages were affected by algal extract with significant increases compared to the control group (p < /em><0.05). Results of serum biochemistry showed that significantly increased total protein, albumin and globulin and also significantly reduced ALT, AST and ALP compared to the control in rainbow trout. CONCLUSIONS: Based on the results of this study oral use of red algae (L. caspica) as an immune stimulant in rainbow trout (O. mykiss) was recommended.

BACKGROUND: Replacement of natural materials with syntheticdrugs in order to increase production and safety. OBJECTIVE: The purposeof this study was to investigate the effect of feed supplemented with ginger (Zingiberofficinale) extract on the growth, biochemical and hemato-immunologicalparameters of rainbow trout (Oncorhynchus mykiss). METHODS: Fishwith an average body weight 14.1±0.2 g were fed diet for 8 weeks with 0.5% and1% ginger extract and with unsupplemented commercial diet as the control. Bloodsamples were collected from caudal vein from apparently healthy fish at the endof trial. Growth (weight gain, specific growth ratio and condition factor),hematological (RBC,WBC, Hb, Hct, monocyte, lymphocyte and neutrophil),Biochemical (glucose, total protein, triglycerides, cholesterol, albumin, AST,ALT, LDH and ALP) and immunological (lysozym activity, ACH50,IgM, and SOD)parameters were determined. RESULTS: The results showed that there wereno significant differences (p>0.05) in growth, hematological, biochemicaland metabolic enzymes between fish fed control and ginger extractsupplementation. The lowest level of cortisol was observed in 0.5% gingerextract (p<0.05). Lysozyme activity was significantly increased in 0.5%ginger extract fed fish (p<0.05). CONCLUSIONS: The results suggestthat by using 0.5% ginger extract there will be an improvement in growth andimmune function of rainbow trout

BACKGROUND: Enzymes are organic catalysts that trigger and/or accelerate chemical reactions. OBJECTIVES: This research was done to compare the separate and combined levels of commercial multienzymes on feeding efficiency and carcass chemical composition of common carp (Cyprinus carpio). METHODS: Total number of 96 common carp fingerlings weighing 13.06±2.56g were distributed in six treatments including control (without multienzyme), 1 g/kg Combo, 1.5 g/kg Combo, 1 g/kg Natuzyme Plus, 1.5 g/kg Natuzyme Plus and mixture of 1g/kg Combo+1 g/kg Natuzyme Plus in two replicates for 8 weeks. RESULTS: Growth indices such as the final weight, percentage of body weight increase, specific growth rate, food conversion ratio and average daily growth in treatment 1g/kg Natuzyme Plus showed significant differences compared to other experimental treatments (P<0.05). Also, all experimental treatments had better condition in comparison with the control. The highest condition factor was seen in fish fed 1.5 g/kg Natuzyme Plus which showed significant difference with 1.5 g/kg Combo (P<0.05). Common carp fingerlings fed mixture of Combo+Natuzyme Plus recorded a slight increase in protein content of carcass compared to other dietary treatments. Fish fed multienzymes had less (P>0.05) lipid content of carcass in comparison with the control. There was no significant difference in ash and moisture contents of carcass (P>0.05). CONCLUSIONS: According to results, it can be stated that Natuzyme Plus at the level of 1.5 g/kg can be effective in improvement of growth performance and feed efficiency in farmed common carp fingerlings.

BACKGROUND: Balance in the amount of minerals in the aquatic animal’s diet is very important. Phosphorus is one of the most important minerals in fish and aquatic animal’s nutrition. Phosphorus is important not only for the proper growth and fish health, but also for excessive phosphorus excretion that may cause water pollution and algal bloom. OBJECTIVE: In this study the effects of adding monoammonium phosphate in the diet of fish (Cyprinus carpio Koi) and its comparison with monocalcium phosphate were investigated. METHODS: 650 koi fish weighing 17 g were distributed in 15 tanks (5 treatments - each in three replicates) and mono-ammonium phosphate-fed diets at three levels (0.75, 1.5 and 3% of the diet), monocalcium phosphate in one level (3% of the diet) and a control group (no phosphorus supplementation) were fed for 8 weeks. RESULTS: Growth indices and feed conversion ratio in fish fed 3% monoammonium phosphate showed the best results. The control group showed the lowest weight gain and the highest feed conversion ratio. Blood phosphorus was also significantly correlated with increasing monoammonium phosphate. The highest level of calcium in the blood was observed in the group fed monocalcium phosphate (3%). CONCLUSIONS: Considering the improvement of growth and nutrition indices, adding 1.5 to 3% monoammonium phosphate in the diet of koi fish was suggested.

BACKGROUND: Probiotics and prebiotics are the most important bioactive compounds for aquatic health. OBJECTIVES: In this study, the effects of prebiotic (immunowall) and probiotic (primalac) were assessed on growth performance, survival, body composition, and blood biochemical parameters in the Caspian Sea common carp Cyprinus carpio fingerlings. METHODS: Juveniles (n = 100 per tank, 21 tanks) were distributed in four inclusion levels (each in three treatments) of 0, 0.05, 0.1 and 0.15% of immunowall and primalac inclusions for a period of 56 days. Growth, body composition, and hematological parameters have been evaluated in different inclusion levels at the end of culture period. RESULTS: The increment of body weight, specific growth rate, and feed conversion ratio in fish fed with diets containing 0.15% prebiotic and 0.1% probiotic improved considerably compared to other treatments. The survival rate of the juveniles was not significant between treatments, and the group fed with the pre- and probiotics revealed higher survivals. Protein content in the group fed with the pre- and probiotic showed significantly higher contents compared to the control group, and lipid content showed increasing trend in different inclusions. The red blood cells contents showed no differences between treatments; but the white blood cells contents revealed higher performances in the fish-fed probiotics compared to prebiotic and control groups. CONCLUSIONS: These results recommend the addition of 0.1 % immunowall and 0.15 % primalac in the diets of the juveniles in terms of growth, feeding, and hematological indicators in the Caspian carp.