Ive got a few 12-16in Hoplias im looking to rehome. These were caught in Ecuador. Under certain lighting conditions, these sport a nice blue tinted coloring on the sides of the head and gill plate. After viewing on a VERY reputable sponsors forum, he believes these might be the adult version of Hoplias Prognatus. I purchased them as Hoplias Malabaricus. Of ALL the Hoplias ive EVER owned, these Hoplias from Ecuador have the LARGEST heads of ALL. Im asking $50 and UP! Depending on the size taken. 
