A Preliminary Assessment of Microalgae (Spirulina spp.) Based Diet on Performance of Juvenile Koi (Cyprinus rubrofuscus)

This study evaluated the impact of Spirulina-supplemented feed on the growth performance of koi fingerlings (Cyprinus rubrofuscus) over a 5-week period. The experiment aimed to compare the effects of control feed (T1) and Spirulina-supplemented feed (T2) on key growth metrics, including weight gain, daily weight gain (DWG), specific growth rate (SGR), relative weight gain (RWG), and feed conversion ratio (FCR). A total of 15 fingerlings were randomly assigned to two groups, with each group receiving either regular feed or feed supplemented with 1 g/kg of Spirulina. Results showed that the Spirulina-fed group (T2) demonstrated superior performance, achieving a cumulative weight gain of 12.83 g and DWG of 3.49 g/day by the end of the study, compared to 5.88 g and 0.14 g/day, respectively, in the control group (T1). While the SGR improvement was minor, with T2 peaking at 0.15% and T1 at 0.12%, the RWG of the Spirulina group (46.99%) was significantly higher than that of the control group (15.31%). However, the enhanced growth came at the expense of feed efficiency, as the FCR for T2 was 2.14, compared to 1.07 in T1. These findings suggest that Spirulina supplementation enhances growth performance and nutrient utilization, though it requires higher feed input for similar efficiency. The study concludes that Spirulina can be an effective dietary supplement for aquaculture to improve productivity, particularly when rapid growth is prioritized.