Enables histone demethylase activity. Acts upstream of or within cardiac muscle hypertrophy in response to stress and negative regulation of histone H3-K9 trimethylation. Located in pericentric heterochromatin. Is expressed in several structures, including branchial arch; central nervous system; dorsal root ganglion; early conceptus; and genitourinary system. Orthologous to human KDM4A (lysine demethylase 4A). [provided by Alliance of Genome Resources, Apr 2022]