yea that's an oscar.
I got 12 for free from petsmart. they out grew their tank and no one wants them.
quarantined them for about a month and fed them with cichlid gold and so far my rhoms love them. the blue already made two kills. he basically attacks them as soon as he sees one in his tank. black made one kill so far while in that tank. the blue is way more aggressive than the black and less shy, so far so good
since I moved the black diamond to my 75g I've been feeding him shrimp, squid and fish filet only. so far he's not eating as aggressive as when he was feeding on oscar.