Predicted to enable ammonium channel activity. Acts upstream of or within ammonium transmembrane transport and urea transport. Predicted to be located in membrane. Predicted to be active in plasma membrane. Is expressed in several structures, including ball; cardiovascular system; gill; hematopoietic system; and pleuroperitoneal region. Human ortholog(s) of this gene implicated in Rh deficiency syndrome; hemolytic anemia; and overhydrated hereditary stomatocytosis. Orthologous to human RHAG (Rh associated glycoprotein).