The effects of diets supplemented with spirulina platensis in different quantities on pigmentation and growth performance of Goldfish (Carassius auratus)

Abstract

Spirulina sp., a blue green algae, is in the form of a spiral ring with microscopic cells. S. platensis contains 60% vegetable protein, essential vitamins and β-carotene which is an important antioxidant. Spirulina’s dark green colour is due to the pigments of carotenoid (orange), phycocyanin (blue) and chlorophyll (green). Green chlorophyll is masked by blue phycocyanin, which is an auxiliary pigment, alloficocyanin and red coloured phycoerythrin. The only chlorophyllin that Spirulina sp. contain is chlorophyll a and its amount varies between 0.81.5% in dry weight. Xanthophyll content of freeze-dried Spirulina sp is quite high and it accounts 6.9 g.kg-1. Other major carotenoids are mycoxanthophyll (37%), β-carotene (28%) and zeaxanthin (17%). Due to its pigment composition, Spirulina sp. is utilized for pigmentation of ornamental fish used as a feed additive particularly in Goldfish. If the colour formation of Carassius auratus cannot be achieved at the desired level, it leads to decrease in market demand and value of such a fish significantly. Even though fish feeds containing carotenoids are available in the market, these feeds are quite expensive. For this reason, we investigated the effects of Spirulina platensis on pigmentation and growth of the Goldfish in the study. In this context, Specific Growth Rate (SGR), the Feed Conversion Ratio (FCR), Condition Factor (CF) and Survival Rate (SR) were investigated to evaluate the growth performance of C. auratus species through usage of 3 different feed quantities (25 mg.kg-1 diet, 50 mg.kg-1 diet, 75 mg.kg-1 diet). This study demonstrated that S. platensis added to fish-feed in various quantities had no significant effect on the growth of Goldfish however it contributed to skin pigmentation. The best carotenoid ratio was achieved in the feeding group in which 75 mg.kg-1 of S. platensis was supplemented to the diet. The goal in this study, the effects of the addition of Spirulina sp. as a carotenoid source at different levels to the fishfeed on the growth, development and pigmentation of Goldfish (Carassius auratus) were investigated.