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: 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.

BACKGROUND: Based on previous studies, aquaculture systems affect on flesh quality in cultured species. In biofloc system, as a modern and new aquaculture system, animals use microbial flocs as feed and it seem such flocs affect on bodycomposition. OBJECTIVES: The aim of this study was to evaluate growth and chemical, microbiological and sensory properties of common carp meat cultured in Biofloc system. METHODS: Three hundred healthy fingerlings were randomly distributed in 12 tanks (70 L) at a density of 8.3 kg m-3 and fed experimental treatments: commercial diet as a control and three biofloc treatments including sugar beet molasses biofloc (SBM+BFT), sugar biofloc (S+BFT) and corn starch biofloc (CS+BFT). Fish in BFT treatments were fed at 75% of the daily feeding rate of control. At the end of experiment, growth performance and survival investigated. In addition to evaluate cultured fish meat quality, sensory properties of raw fish (day 0), rigor mortis (3, 6 and 24 h after catch), bacterial count, pH, expressible moisture and TVN were also assessed during 16 days, (every 4 days). RESULTS: The results indicated that the lowest food conversion ratio (FCR) and highest condition factor was observed in fish fed BC which differed significantly from control (P<0.05). No significant difference among treatments was observed in rigor mortis and bacterial count (P>0.05). pH in carp flesh increased gradually during storage time (P<0.05), but at the end of the storage period no significant difference was found between the treatments (P>0.05). The lowest primary TVN was seen in BS treatment (9.0 ± 0.2 mg N/100g flesh) but in other treatments TVN was higher than 20 mg/ 100g flesh (P<0.05). CONCLUSIONS: Overall, based on the results of this study, biofloc cultured fish flesh had acceptable quality in comparison with control fish.

Koi herpesvirus (KHV) has infected farmed common carp in Poland clinically and asymptomatically since 2004. The role of non-carp species as vectors of virus transmission is well known except for in the case of KHV. The aim was to better understand this virus’ infection and transmission pathways in common carp, looking at the potential vector role of fishes kept with them. Eight species were experimentally infected with KHV by immersion in a suspension at 20°C ±1 and transferred to a tank after 45 minutes. Specimens were euthanised at intervals up to 56 days post infection (dpi) and tissue was examined for KHV DNA. Surviving infected fishes were introduced at intervals, each time into a separate tank, to naïve common carp for experimental infection. These were observed daily for symptoms, sacrificed along with controls after three months, and dissected to provide tissue samples. Also fish from 14 species collected from a farm with a history of KHV were sampled from 3 to 22 months after disease was confirmed. Organ sections from single fish were collected in a single tube. Viral DNA was detected in tench and roach samples up to 49 dpi, but in three-spined stickleback and stone maroko samples only up to 14 dpi. Transmission of KHV to naïve carp occurred after cohabitation. KHV DNA was detected in three fish species three months after the farm outbreak. We confirmed that grass and Prussian carp, tench, roach, and brown bullhead can transfer the virus to naïve common carp.