The Collaborative International Dictionary of English v.0.48:
Soapfish \Soap"fish`\, n. (Zool.) Any serranoid fish of the genus Rhypticus; -- so called from the soapy feeling of its skin. [1913 Webster]WordNet (r) 3.0 (2006):
soapfish n 1: fishes with slimy mucus-covered skin; found in the warm Atlantic coastal waters of America