Enables sphingolipid delta-4 desaturase activity and sphingosine hydroxylase activity. Acts upstream of or within ceramide biosynthetic process and sphinganine metabolic process. Predicted to be located in endoplasmic reticulum and membrane. Predicted to be integral component of membrane. Is expressed in stomach. Orthologous to human DEGS2 (delta 4-desaturase, sphingolipid 2). [provided by Alliance of Genome Resources, Apr 2022]