Predicted to enable hyaluronan synthase activity. Acts upstream of or within several processes, including circulatory system development; dorsal convergence; and fin regeneration. Predicted to be located in Golgi apparatus and endoplasmic reticulum membrane. Predicted to be active in plasma membrane. Is expressed in several structures, including cardiovascular system; mesoderm; pericardial region; presumptive paraxial mesoderm; and swim bladder bud. Orthologous to human HAS2 (hyaluronan synthase 2).