In order to exploit a new type of food source, enzamatically modified hydrolysates and the plasteins synthesized from the filefish (Nevoden modestus) protein hydrolysates by plastein reaction were investigated. The optimum conditions for enzymatic hydrolysis of filefish muscle and synthesis of plasteins using papain, pepsin, $alpha-chymotrypsin$ and protease (from Streptomyces griceus) were determined. The optimum temperature and pH for the hydrolysis of filefish muscle by papain, pepsin, $alpha-chymotrypsin$ and protease were $50^{circ}C,;40^{circ}C,;55^{circ}C;and;50^{circ}C$; and 6, 2, 7 and 8, respectively. Those for incubation time and enzyme concentration were 4hr, $0.5\%$ for papain and protease, 24hrs $1.0\%$ for pepsin and $alpha-chymotrypsin$. The pepsin was found to be more reasonable substrate for plastein synthesis from the economic point of view. The enzyme-induced plastein reaction could be optimized, namely, pH 4 for pepsin, pH 7 for $alpha-chymotrypsin$, pH 6 for papain and protease: substrate concentration $40\%$ for pepsin, $alpha-chymotrypsin$ and protease, $50\%$ for papain; the time of incubation, 24hr; enzyme_{strate ratio, 1 : 100(W}V) ; incubation temperature, $50^{circ}C$.