Enables fumarate hydratase activity. Involved in fumarate metabolic process; positive regulation of cold-induced thermogenesis; and regulation of arginine metabolic process. Acts upstream of or within homeostasis of number of cells within a tissue. Located in mitochondrion. Is expressed in several structures, including alimentary system; genitourinary system; nervous system; respiratory system; and sensory organ. Human ortholog(s) of this gene implicated in fumarase deficiency and lung non-small cell carcinoma. Orthologous to human FH (fumarate hydratase). [provided by Alliance of Genome Resources, Apr 2022]