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.