In this study, we investigated the chemical and enzymatic properties of unmarketable cultured bastard halibut (UCBH) Paralichthys olivaceus harvested at different times (March, May, July, September, November, and January), and we examined the physical properties of surimi gel from UCBH as a potential source of surimi and surimi gel. The moisture and crude protein contents of UCBH harvested in July and January were >78% and <19%, respectively, which is greater than the moisture content in UCBH harvested in May, March, and September, but lower than the crude protein content. Regardless of the month of harvest, the UCBH had a higher crude protein content than Alaska pollock, which is the largest fishery biomass used for surimi and surimi gel, but a lower moisture content. Regardless of the month of harvest, the enzymatic activity in crude extracts of UCBH muscle ranged from 0.31-0.59 U/mg for casein (pH 6.0 and 9.0) and 11.7-12.7 U/mg for LeuPNA. These findings suggest that autolytic enzymes were unaffected by gel formation. Gel strength was highest in the surimi gel prepared from UCBH harvested in September, November, and January; second highest in that prepared from UCBH harvested in March and May; and lowest in that prepared from UCBH harvested in July. Compared to the gel strength of surimi gel from grade SA commercial Alaska pollock surimi, the strength of the surimi gels prepared from UCBH harvested in March, May, September, November, and January were superior, whereas that of the surimi gel prepared from UCBH harvested in July was similar.