Enables mRNA (N6-adenosine)-methyltransferase activity. Involved in mRNA catabolic process; mRNA destabilization; and mRNA methylation. Predicted to be located in cytoplasm. Predicted to be active in nucleus. Is expressed in several structures, including alimentary system; brain; cardiovascular system; genitourinary system; and hemolymphoid system gland. Orthologous to human METTL16 (methyltransferase 16, N6-methyladenosine). [provided by Alliance of Genome Resources, Apr 2022]