The present study was conducted to investigate the effects of the red clover extract on growth, body composition and survival of African catfish Clarias gariepinus. Three concentrations (25, 50 and 75 mg/kg) of red clover at dietary were used for 120 days. The final weights of red clovertreated groups were significantly different from each other and the control group. The best growth was observed in the group receiving the 75 mg/red clover kg diet. Fish fed with all levels of red clover had higher weight gains than the control. The highest values of the specific growth rate and the food conversion rate were 1.14 ± 0.01 and 2.26 ± 0.04, respectively, for the 75 mg/red clover kg diet group. During the red clover administration period, the survival ranged from 97.78% for the 50 p.p.m. group to 95.56% for the 25 and 75 p.p.m. groups. Protein contents of the dosage groups were significantly different from control (P < 0.05). The highest value of protein content (19.97%) was observed for the 75 mg/ red clover kg diet. Lipid and ash contents were significantly affected by the red clover levels in the diets. The highest lipid contents were in the 75 mg/red clover kg diet (4.67%), and the highest ash content was 1.39% for the 25 mg/red clover kg diet.

This study examined the effects of Tribulus terrestris (TT) on sex reversal in guppy, Poecilia reticulata. The objective of this study was to introduce a new environmentally friendly method for masculinization in P. reticulata. Since male guppy has higher commercial value than female. TT is a natural, non-toxic herb which helps enhance testosterone levels in human and animals. It was prepared in a laboratory in France. Different concentration (0.0, 0.05, 0.1 and 0.15 g L(-1)) of TT was investigated for sex reversal in the Poecilia reticulata. TT extract was administered by immersion of newly born offspring once weekly for two months. Among the dosages used in the present study 0.15 g L(-1) TT was the most effective dosage that ensured maximum male ratio (80%, p < 0.01). Although, sex ratios of 0.05 and 0.1 g L(-1) TT were not significantly different from the expected 1:1 ratio, in these two groups treatment with TT also result in higher number of males (58.25 and 59.77%, respectively), than control (p > 0.05). Total survival rates in all treatments and control were uniformly high ranging from 83 to 87% (p > 0.05). It is concluded that TT has no negative effect on survival rate of P. reticulata. All groups of TT-treated fish exhibited successful growth acceleration comparing to the control group, but only TT treatment at the concentration of 0.15 and 0.1 g L(-1) TT significantly improved growth rate of P. reticulata (p < 0.01). Histological examinations revealed that testes of fish treated with TT-extract contained all stages of spermatogenesis. Sex reversal in P. reticulata demonstrated that TT treated new-born progenies showed successful sex reversal, spermatogenesis and better growth rate than untreated progenies.

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We have examined the effects of Tribulus terrestris (TT), a non-toxic herb, on sex reversal in the Convict Cichlid Cichlasoma nigrofasciatum with the aim of introducing a new environmentally friendly method for masculinization in C. nigrofasciatum. TT is a natural plant product that elevates the testosterone levels in humans and animals. Different concentrations (0.0, 0.10, 0.20 and 0.30 g/l) of TT extract were tested for their effect on sex reversal in C. nigrofasciatum by immersing newly hatched offspring once weekly for 2 months in TT extract. Of the dosages used in the present study, 0.30 g/l TT was the most effective in terms of masculinization, resulting in a maximum male ratio of 87.23% (P < 0.001). Sex ratios of 79 and 85% at 0.10 and 0.20 g/l TT, respectively, were also significantly different from the expected 1:1 ratio (P < 0.001). Histological examinations revealed that the testes of fish treated with TT extract contained all stages of spermatogenesis, clearly demonstrating that the administration of TT extract to C. nigrofasciatum stimulated spermatogenesis. Total survival rates in all treatments and the control were uniformly high, ranging from 88.57 to 90% (P > 0.05). We concluded that TT had no negative effect on the survival rate of C. nigrofasciatum. In addition, all groups of TT-treated fish exhibited successful growth acceleration compared to the control group, but only the 0.30 g/l TT treatment significantly improved the growth rate of C. nigrofasciatum. (P < 0.01). Sex reversal in C. nigrofasciatum demonstrated that TT-treated 0-day-old larvae showed successful sex reversal, spermatogenesis and a better growth rate than untreated progenies.

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An eighty‐day feeding study was performed to investigate the effects of mealworm meal (Tenebrio molitor) on the growth, survival and moulting frequency of juvenile Narrow‐clawed crayfish (Pontastacus leptodactylus). Three dietary treatment groups with triplicate were fed with a fish meal‐based without MW (control diet: MW0), two diets with 50% (MW50) and 100% (Mw100) of fish meal substitution with MW respectively. P. leptodactylus juveniles (11.0 ± 0.05 mm, mean ±SE and 0.011 ± 0.002 g, mean ±SE) were randomly stocked into nine flow‐through tanks with a density of 30 crayfish per tank and reared for 80 days. Crayfish fed with MW50 mealworm meal showed positive effects on weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER), apparent net protein utilization (ANPU), moulting frequency (MF) and feed conservation ratio (FCR), but lower survival rate (SR) as compared to the other diet groups. Protein and lipid contents of the whole body of the crayfish fed with replacement diet (MW50) were found to be higher than those of the other two diet groups (p<0.05). However, the MW100 diet slightly increased the moisture and ash contents of the crayfish. Our observation indicated that the addition of a 50% mealworm meal in the diet of P. leptodactylus juveniles improved the growth performance of the crayfish without causing any adverse effects. Therefore, T. molitor meal can be considered as an alternative animal source of protein for the narrow‐clawed crayfish juveniles.

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.

A preliminary study was conducted to evaluate the effect of the Rosemary extract (Rosemaria officinalis) on growth performance, feed utilization and body composition of the African catfish (Clarias gariepinus, Burchell, 1822). Fish with an average body weight of 10.59±0.31 g were fed with different concentrations (0, 0.25 and 0.5 %) of Rosemary extract at dietary for 60 days. At the end of experiment, the highest values of weight gain, specific growth rate and food conversion rate were 17.23±0.08 g, 1.93±0.07 and 1.16±0.06 at 0.5% Rosemary extract dosage group respectively. The highest survival rates were 100% at 0.25% Rosemary extract dosage groups. No significant differences were shown in whole body protein and lipid content among the dietary treatments. These results indicate that treatment of Rosemary extract has positive effect on growth in African catfish with no apparent effects on health status.