عنوان مقاله [English]
A survey was carried out to evaluate the effect of natural (gammarus and marigold) and synthetic (astaxanthin) carotenoids on growth indices, skin color and blood of redhead cichlid (Paraneetroplus synspilus) in spring 2015. Total number of 120 redhead cichlids with an average weight of 9.63 ± 2.90 g were distributed in 12 aquaria and kept at a density of 10 fish per aquarium. Fish were fed four rations including 1- control (skretting without pigment), 2- 100g/kg gammarus in skretting, 3- 100g/kg marigold in skretting and 4- 50 mg/kg astaxanthin in skretting in three replicates for 70 days. At the end of the experiment, blood sampling was conducted via caudal artery or vein (under vertebral column). The highest final weight, total length, percentage of body weight increase, average daily growth, specific growth rate, condition factor, gonadosomatic index and the lowest FCR were observed in fish fed astaxanthin which there were significant differences in gonadosomatic index with other treatments (P<0.05). Fishes fed marigold showed an increase (P<0.05) in RBC, hematocrit and hemoglobin. Fish fed astaxanthin, marigold and gammarus had much astaxanthin (P<0.05) in blood and higher coloration (P<0.05) at the top of opercle and under pectoral fin compared to the control. Based on results, addition of pigment in the diet is mandatory and astaxanthin at the level of 50 mg/kg and marigold at the level of 100 g/kg can play important roles in increasing growth, skin coloration and also improve hematological parameters in redhead cichlid fingerlings.