Copper (Cu) elimination was investigated in the tissue and organs of rainbow trout (Oncorhynchus mykiss, Walbaum, 1792), after Cu-free diets exposure. In the current study, fish were fed to satiation on diets containing 0.022 (Group 1; Control), 0.043 (Group 2), 0.123 (Group 3), 0.424 (Group 4) g Cu*kg -1 diet for 60 days before elimination experiment. A total of 288 fish (mean weight 84.28±1.05 g) were randomly transferred to 12 fibreglass tanks. The fish were fed the Cu-free diet twice daily, until apparent satiation, during 60 days. Subsequently, the experiment was established for a period of elimination, during which samples were taken at days 15, 30, 45 and 60. Cu concentration in the muscle, gill tissue, digestive system, liver and whole body of fish were determined after 60 days depuration.Cu concentrations in tissues of rainbow trout decreased during depuration period, and the order of Cu elimination in tissue and organs of rainbow trout was: digestive system (73.1 %), then gill (41.1 %), muscle (31.5 %) and liver (17.2 %) for group 2; digestive system (74.1%), then muscle (65.8%), gill (60.0%) and liver (34.6%) for group 3; and digestive system (85.8%), then muscle (80.8%), liver (50.5%) and less/equal in gill (50.2%) for group 4. In statistical analysis, both groups and time were significant factors (P<0.05) on elimination rate. Moreover, significant interaction between groups and time were identified on elimination rate. Digestive system showed the fastest elimination rates of Cu at all groups compared with other tissues.

The aim of this study was to investigate the effect of different carotenoid sources on goldfish (Carassius auratus) skin pigmentation. The value of goldfish depends on the intensity of the skin color. In the red variety of goldfish, an orange-red hue is desirable. Juvenile goldfish were fed one of five diets for five months to determine the effects of carotenoids on skin pigmentation, growth, feed efficiency, and survival: (1) astaxanthin (carophyll pink at 75 mg/kg), (2) canthaxanthin (carophyll red at 75 mg/kg), (3) Gammarus spp. (75 mg/kg), (4) Oleoresin paprika (180 mg/kg), and (5) an unsupplemented control. Growth and feed efficiency did not significantly differ among groups. Initial and final samples of head skin were measured by colorimetric analysis for lightness (L*), redness (a*), yellowness (b*), hue (Hº ab), and chroma (C ab *). The best red color (a* and Hº ab) was obtained with the astaxanthin, canthaxanthin, and paprika diets.

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This research was designed in order to examinate the effects of 17α-methyltestosterone and 17β-estradiol hormone use on the development, growth performance, survival, sex ratio and coloration of the electric yellow cichlid (Labidochromis caeruleus Fryer, 1956). Seven different groups were designed in the study. While no hormones were added to the control diet, 6 different rates of hormones were added to the other groups. Cichlid mean weight was determined as 0.64±0.01 g, were stored such that three replications for each group. The fish were fed with the feeds for a period of 2 months. At the end of this research, the highest weight gain was determined in the 20 mg kg -1 17α-MT group (0.39±0.17 g). When the sex change rates were evaluated, it was determined that the feminization rates in the 17β-ES hormone group were 80.00%, 82.22% and 86.67%, respectively, and all fishes in the 17α-MT hormone group were 100% male. When the results of the physical color analysis were evaluated, it was determined that the best coloration was obtained in the 17α-MT groups. At the end of the study, the 17α-MT hormone was determined to have a better effect than 17β-ES hormone on the growth, feed conversation rate, sex change and pigmentation of electric yellow cichlid (Labidochromis caeruleus Fryer, 1956).

This study was performed to investigate the effects of 17b-estradiol (ES) and 17a-methyltestosterone (MT) on growth, development, survival, sex ratio and colour change in the electric blue hap (Sciaenochromis ahli Trewavas, 1935). The hormones were not supplemented to the control feed, while six other feeds were prepared by adding 20, 40 and 60 mg kg À1 17b-ES or 20, 40 and 60 mg kg À1 17a-MT to each, resulting in seven different feed treatments. Average live weight of the fish supplemented with these diets was 0.42 AE 0.04 g. At the end of the study, the highest weight gain was observed in fish fed 60 mg kg À1 17a-MT group (2.62 AE 0.11 g) and the difference with the groups fed with 17b-ES was found to be significant. All fish fed 17a-MT were male, while the rates of feminization in fish fed 17b-ES at 20, 40, 60 mg kg À1 were 91.11%, 88.88% and 93.33% respectively. Survival rates were respectively determined as 80%, 95.56%, 84.44%, 93.33%, 77.78%, 84.44% and 84.44% for the control, 20, 40, 60 mg kg À1 17b-ES and 20, 40, 60 mg kg À1 17a-MT treatments. The best colouration was achieved in the 17a-MT groups (P < 0.05). The L* values varied between 32.98 AE 4.44 and 61.35 AE 2.19, a* values between À7.06 AE 0.22 and À3.42 AE 0.11, and b* values between À7.74 AE 0.10 and 11.65 AE 0.03, while Chroma (C*) and Hue (H°a b ) angle values varied between 7.54 AE 0.22 and 13.60 AE 0.01 and between 119.76 AE 0.05 and 239.73 AE 4.86. In conclusion, the 17a-MT feeding was found to have a greater effect on the growth, feed conversion ratio, masculunization and pigmentation of the electric blue haps than the 17b-ES treatment.