Effects of dietary Arthrospira platensis supplementation on the growth, pigmentation, and antioxidation in yellow catfish (Pelteobagrus fulvidraco)

Spirulina, Arthrospira platensis, contains high levels of protein and lutein. To evaluate nutritional, pigmentation, and antioxidation effects of A. platensis, a total of 900 juvenile yellow catfish (Pelteobagrus fulvidraco) were divided into 18 tanks (3 tanks/treatment, 50 fish/tank) and fed a diet supplemented with A. platensis for 50 days. A. platensis was used in quantities of 0, 57.6, 115.1, 172.7, 230.3, and 287.9 g kg(-1) for experimental diets to replace fishmeal protein at levels of 0 (AP0), 20% (AP20), 40% (AP40), 60% (AP60), 80% (AP80), and 100% (AP100). Results revealed that substituting up to 80% of fishmeal by A. platensis biomass did not have a negative effect on fish growth, feed utilization, or apparent digestibility. However, significantly lower growth rates were observed when 100% of the fishmeal was substituted (P < 0.05). A. platensis replacement groups led to an increase in skin yellowness and dose-dependent enrichments of total lutein in dorsal skin, abdominal skin, and liver tissues (P < 0.05). There were similar enhancements observed in glutathione concentrations and glutathione peroxidase activities in plasma and liver (P < 0.05). Analyses based on lutein concentration between abdominal skin and experimental diets revealed that the optimal substitution amount was 72.03% (207.4 g kg(-1) of A. platensis), which could ensure growth and pigmentation in yellow catfish.