Enables glutathione transferase activity. Predicted to be involved in glutathione metabolic process. Predicted to be active in cytoplasm. Is expressed in brain; gill; liver; and pleuroperitoneal region. Human ortholog(s) of this gene implicated in Alzheimer's disease; Parkinson's disease; and asthma. Orthologous to several human genes including GSTO1 (glutathione S-transferase omega 1).