Enables histone H4-methyl-lysine-20 demethylase activity. Involved in epigenetic maintenance of chromatin in transcription-competent conformation; histone H3-K9 demethylation; and histone H4-K20 demethylation. Predicted to be located in kinetochore; nucleolus; and nucleoplasm. Is expressed in several structures, including alimentary system; eye; genitourinary system; nervous system; and respiratory system. Orthologous to human PHF2 (PHD finger protein 2). [provided by Alliance of Genome Resources, Apr 2022]