Glass transition of fresh red meat of bigeye tuna (Thunnnas obesus) and its filtrate occurred between —71°C and —68°C, independent of cooling rate from 1 K/min up to 50 K/min. Glass transition at low temperature appeared to occur in the liquid part. Neither dilution nor concentration of the filtrate affected the glass transition temperature (Tg) but the solute concentration of the freeze concentrated phase (Cg) was affected. Addition of salt to the filtrate caused a decrease of ∼20 K in Tg. Results suggested the possibility of qualitative improvement in quality of fish by lowering the storage temperature by 15 K below the present storage temperature (—55°C).