Enables potassium channel activity. Predicted to be involved in potassium ion transmembrane transport. Predicted to act upstream of or within monoatomic ion transmembrane transport and potassium ion transport. Predicted to be located in membrane. Predicted to be active in plasma membrane. Is expressed in several structures, including eye; gill; heart; integument; and pleuroperitoneal region. Orthologous to human KCNK5 (potassium two pore domain channel subfamily K member 5).