The effects on growth and body composition that result from tuna byproduct meal (TBM) substituted for fish meal in the diet of juvenile abalone, Haliotis discus, were determined. One thousand two hundred and sixty juvenile abalone were randomly distributed into 18 70-L plastic rectangular containers. Six experimental diets were prepared in triplicate. The TBM0 diet included 28% fish meal and 13% soybean meal as the protein source. Twenty-five, 50, 75, and 100% of the fish meal were substituted with TBM, referred to as TBM25, TBM50, TBM75, and TBM100 diets, respectively. Finally, salted sea tangle (ST) was prepared. The essential amino acids, such as isoleucine, lysine and valine, tended to decrease with the dietary substitution of TBM for fish meal in the experimental diets. The weight gain and specific growth rate (SGR) of abalone that were fed the TBM25 diet were significantly higher than those of abalone that were fed the other diets (P < 0.05). The crude protein content of the soft body of the abalone linearly decreased with dietary substitution of TBM for fish meal. In conclusion, as much as 75% of the fish meal in the diet of abalone can be replaced with TBM without a retardation in weight gain and SGR of the abalone when 28% fish meal was included.