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AbstractCommon carp (Cyprinus carpio) is the most farmed freshwater fish worldwide. In recent years, use of natural products in fish diets has become popular in aquaculture, to improve fish health and growth performance. The present study investigated the effects of essential oil from the leaves of Monterey cypress (Cupressus macrocarpa; CMEO) on growth performance and blood parameters in common carp fingerlings. Identification of 96.1% of the CMEO total volatile components was achieved, with the highest contents for terpinen-4-ol and α-pinene, at 22.9% and 47.7%, respectively. After 60 days of feeding of the fingerlings with supplemented diets without CMEO (CMEO 0%) and with CMEO at 0.5%, 0.75% and 1%, the best growth performance was seen for those fish fed with the CMEO 0.5% diet. No significant differences were seen for the haematological parameters and blood cell indices versus CMEO 0%. Serum glucose, triglycerides, cholesterol and glutamic pyruvic transaminase were significantly reduced in the fingerlings fed with the CMEO 0.5% diet versus CMEO 0%. Thus, CMEO oil as a 0.5% dietary supplement can be used to improve the growth performance and health status of the common carp without any adverse effects seen.

In the present study, fish meal (FM) was replaced by pea (Pisum sativum) protein (PP) in diet for Rainbow trout (Oncorhynchus mykiss) at levels of 0% (PP0), 25% (PP25), 50% (PP50), 75% (PP75) and 100% (PP100), and the effect of dietary PP level on the digestive system tracts and liver was investigated by micromorphological and histopathological evaluations. Morphometric measurements (mm 100g fish −1 ) of the liver width and stomach length in rainbow trout were found to be significantly larger (p <0.05) in fish with high-level pea protein as the main protein source (PP75, PP100) compared to the low-level PP replacement group (PP25). No significant differences were found in morphometric measurements for pyloric caecum and intestines among treatment groups, whereas the number of the caecum of fish fed the PP25 diets significantly increased over the control (PP0) (p<0.05). In the histological examination of the liver, mild hydropic and vacuolar degeneration was observed in all experimental groups except PP0 and PP25. The measurements of pyloric caecum fold height, enterocyte length and width of tunica muscularis of the high-level pea protein groups of PP75 and PP100 were significantly higher (p <0.05) compared to the control group. In conclusion, 25% substitution of PP can be suggested for FM in trout diets, because the findings of the present study provided evidence that the digestive system improved by increasing the number of pyloric caecum at this replacement level.

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As from January 2010 The Israeli Journal of Aquaculture-Bamidgeh (IJA) will be published exclusively as an on-line Open Access (OA) quarterly accessible by all AquacultureHub (http://www.aquaculturehub.org) members and registered individuals and institutions. Please visit our website (http://siamb.org.il) for free registration form, further information and instructions. This transformation from a subscription printed version to an on-line OA journal, aims at supporting the concept that scientific peer-reviewed publications should be made available to all, including those with limited resources. The OA IJA does not enforce author or subscription fees and will endeavor to obtain alternative sources of income to support this policy for as long as possible.

The effects of different dietary protein levels on growth performance and health status of TwobandBream Diplodus vulgaris juveniles were investigated. Three test diets that had increasing protein levels (30, 36, and 42%) and used fish meal as the protein source were formulated. Each of the test diets was fed in triplicate groups of 28 juvenile fish (initial weight, 23.65 ± 0.34 [mean ± SD]) to satiety for a period of 80 d. Growth performance and feed utilization were best in the group fed the diet with a protein level of 36%. Ammonia nitrogen excretion showed an increasing trend as dietary protein levels increased, and retention rates of ammonia nitrogen per intake were highest in fish fed the 42% protein diet. Whole‐body proximate composition and hematological variables were not significantly affected by protein level in the diets. However, serum glucose, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) values were significantly affected by dietary protein level and showed an increasing trend as the dietary protein level in the diets increased. As a result, an improved health status of Twoband Bream was observed in the fish fed a 36% protein level.

The aim of the study was to determine the potential and sustainable use of pre-commercial product ITTINSECT™ APS V1 as a major protein source in rainbow trout (Oncorhynchus mykiss) diets. A 60-day feeding experiment was conducted to potentially use ITTINSECT as fish meal replacement in the diets of rainbow trout. Five isonitrogenous in dry matter (38% crude protein) and isolipidic (15% crude lipid) diets were produced: a control diet (fishmeal-based) (ITT0) and four experimental diets replacing fishmeal by 25 (ITT25), 50 (ITT50), 75 (ITT75) and 100 (ITT100) %, with ITTINSECT™ APS V1. Triplicate tanks, containing 15 fish each (65.81 ± 1.26 g), were hand-fed to apparent satiation twice every day during the experiment. At the end of the feeding trial, significantly higher growth performance was observed in the group fed ITTM25 and ITTM50 diets. This performance was supported by growth-related gene expressions analyzed in muscle; significantly higher GH and IGF-I genes expression levels were determined in ITT25 and ITT50 when compared to control (ITT0) (p < 0.05). While no significant differences were found between the hematology values (p > 0.05), serum total protein, globulins and glucose levels were significantly different between experimental groups (p < 0.05). In addition to this, the immune-related genes such as TNF-α, IL8 and IL1-β expression levels were determined to be significantly different (p < 0.05). In conclusion, in order to achieve the best growth performance in rainbow trout and enhance sustainable aquaculture practices, replacement of fish meal with up to 50% ITTINSECT™ APS V1 in diets for rainbow trout is suggested.

Rainbow trout (Oncorhynchus mykiss) were fed replacement of fish oil with diets including poppy seed oil (PSO; 0%, 50% and 100%). At the end of the 90‐day feeding period, the water holding capacity of the fillets decreased when the storage time increased. The colour and pH values were affected by both storage and diets. The hardness, springiness, gumminess and chewiness index of the fillet samples decreased as a consequence of increasing storage time, whereas the cohesiveness values of the fillets increased. The addition of PSO increased unsaturated fatty acids and reduced saturated fatty acids in the fatty acid composition of the fillets. These results demonstrated that the fatty acid (FA) composition of the rainbow trout fillets was reflecting the FA composition of dietary treatments and oils sources. The total mesophilic and psychrophilic bacteria count of the fish oil (FO), poppy seed oil/fish oil (PSO/FO) and poppy seed oil (PSO) samples was found within the legal limit on the third day of storage; however, it was found above the legal limits on the fifth day of storage. The sensory evaluation results showed that the fish fed with PSO diet were found to be non‐desirable. The results of the study suggested that the blend of 50% fish oil and 50% poppy seed oil could be used as a replacer of fish oil in diets for rainbow trout to obtained the best growth performance, fillet quality and storage conditions.