Bioadhesive strength between biofilm from yellowfin tuna (Thunnus albacares) gelatin and rat skin treated with glutaraldehyde was compared with bovine and porcine gelatin. Tuna biofilms treated with 0.5 M glutaraldehyde at 60 ℃ and neutral pH for 2 h had an increase in bioadhesive strength of approximately five times when compared with intact tuna biofilms. When glutaraldehyde-treated tuna biofilms were applied with sodium borohydride, the bioadhesive strength was reduced to the level of intact tuna biofilms. The bioadhesive strength of tuna biofilms was superior to those of bovine and porcine gelatin biofilms.