The effect of natural and synthetic carotenoid source, fish size and tank colour, on the pigmentation of golgfish

In this study, the effect of tanks color and fish size on red pigmentation of gold fish (Carassius auratus, Cyprinidae) was investigated. Experiments were carried out at Çukurova University, Faculty of Fisheries, fish production facilities between March 20, 1995 and September 2, 1995. Fish samples of yellow-red varieties supplied by aquarium fish producers in the region. Three different experiment each lasting 60 days were earned out indepently. In each experiment pigmentation weight and legth of fish were measured in 20 day intervals. The data were analyzed using "Analysis of Variance (ANNOVA) " and "Duncan Multiple Comparison Test". Two methods; color scale method and spectrophotometric method were used to measure pigmentation. Colour scale was consisting of 8 tones of yellow-orange colour. In spectrophotometric method, total carotenoid deposition in fish skin was determined. Total carotenoid concentration was determined spectrophotometrically. 1% astaksantin acetone solution theoretical molar absoiption coefficient was for 1 cm cuvette, under 475 nm was taken as 2000. Experiment J: In this experiment fish were fed on by on diets containing 75 mg/kg zeaxanthin, astaxanthin, zeaxanthin+aslaxanthin, 6% alfalfa, red pepper, carrot or plankton {Daphnia spp. and Scenedesmus spp.). At the end of the experiment the diets caused the following total carotenoid accumulation in the skin of the fish; 33.52±0.62 mg/kg for zeaxanthin, 29.84±0.50 mg/kg for red pepper, 27.07±0.62 mg/kg for Daphnia spp., 26.52±0.42 mg/kg for Scenedesmus spp., 25.84±0.62 mg/kg for astaxanthin+zeaxanthin, 23.95±0.68 mg/kg for astaxanthin, 19.95±0.66 mg/kg for carrot, 16.58±0.64 mg/kg for alfalfa, 11.59±0.33 mg/kg for control group. Duncan test showed that all experimental diets gave significantly different pigmentation than the control group significantly (P<0.05). Zeaxanthin, red pepper and planktonic organisms were more effective in pigmentation of the fish than the other diets. Similar results were obtained both with spectrophotometric methot in the color scale. Red pepper gave statistically better growth than that of the other feeds (P<0.05). This effect is attributed to Capcaisin content of the pepper which gives hot spicy test. This material is thought to increase enzymatik reaction and segration of digestive enzymes which improve digestion. Feed conversion ratio was similar for in all groups. It was also62 calculated that while carotenoid sources decreased feed costs 2 %, carrot, synthetic caretonoids and red pepper increased the feed cost by 2%, 9.8% and 18 % respectively. When the other characteristics of pigment sources that mentioned above are considered these costs were not significant. Experiment 2 : Total carotenoid accumulation in the skin of four different fish groups fed on a diet containing zeaxanthin (75 mg/kg) was as follows; 19.23±0.46 mg/kg for 1.52 g weight group, 29.06±0.64 mg/kg for 4.19 g weight group, 31.10±0.53 mg/kg for 7.35 g weight group, 35.28±0.65 mg/kg for 13.1 1 g weight group. According to these results it was concluded that pigmentation increased with fish weight. Experiment 3 : Total caretonoid accumulation in the skin of the fish fed on 75 mg/kg zeaxanthin ration was as follows; 34.41 ±0.56 mg/kg in green tanks, 32.90±0.42 mg/kg in blue tanks, 28.60±0.74 mg/kg in red tanks, 28.58±0.52 mg/kg in white tanks and 26.96±0.7() mg/kg in yellow tanks. Pigmentation in green and blue tanks higher and statistically significant compared to the other tanks (P<0.05). Similar results were obtained with color scale method. In addition, it was observed that fish grew more in green and blue tanks. No significant difference was observed in terms of feed conversion ratio. It was concluded that presence of zeaxanthin ( syntethic carotenoid source) and red pepper (natural carotenoid sources) and planktonic organisms result in a substantial pigmentation in goldfish. Color of the fish tanks also affect fish pigmentation blue and green tanks are suitable for increasing fish pigmentation, and blue and green colored environments are suitable for increasing pigmentation. High mortality rales obtained in red tanks indicate that this color causes stfess on fish. Different weight groups reacted differently to carotenoid tteatments. Pigmentation level increases as the fish gains more weight. For this reason, the fish must be at a certain weight if they are to be pigmented with carotenoid suplemented diets. According to the results of this study the the weight of the fish must be above 4 g. Under the conditions mentioned above it should be possible to increase red pigmentation in goldfish skin which of course will substantially increase market ability and market value of the fish.