DIADEMICHTHYS LINEATUS or Clingfish.. This is what we refer to as a kind of CLING FISH . This lives commensal on the Long Spine Urchin named Diadema setasum.. I have attached pictures. On the same Urchin lives a Pistol shirmp with EXACT the same colors and pattern named : STEGAPONTONIA COMMENSALIS.. ( Picture by Gary Bell ) The Clinfish has the Latin name DIADEMICHTHYS LINEATUS , though there is also an other one , but not found here..It carries a "suction cup "on the belly and clings to one of the spines of the urchin that way They make great fish for the so called NANO REEFTANKS...