Jack-knifefish Eques/Equetus lanceolatus

The Jack-knifefish is a Drum, named afer a repetitive drumming sound it makes, and also after the very high dorsal fin like the blade of a jack-knife. It is native to the Western Atlantic coast from North Carolina to Brazil and the Caribbean. They can grow to 25 cm long. It is one of only two species in its genus, the other being the Spotted Drum with a range from the Gulf of Mexico to the Caribbean (although there are nearly 300 species in the family of drums and croakers).