Enables ammonium transmembrane transporter activity and cation:chloride symporter activity. Involved in ammonium import across plasma membrane. Acts upstream of or within chloride transmembrane transport. Located in plasma membrane. Is expressed in vestibulo-cochlear ganglion. Orthologous to human SLC12A7 (solute carrier family 12 member 7). [provided by Alliance of Genome Resources, Apr 2022]