Hormone which plays a role in endochondral ossification through regulation of cartilaginous growth plate chondrocytes proliferation and differentiation. May also be vasoactive and natriuretic. May be important for freshwater adaptation. Highly expressed in brain and liver, and moderately in gut, gills and heart. Expressed to a low level in atrium, ventricle and liver of fresh water eels. Expression is generally higher in freshwater eels than in saltwater ones, except in brain, where the levels are the same. Belongs to the natriuretic peptide family.