Meet Hannibal - Gymnothorax Undulatus - Undulated Moray
~16" when I got him, 4' and as big around as my upper arm when he died 25 years later.
He spent most of his time with me in a 150 long, eventually by himself. He'd eat anything else I tried to keep with him including a saucer sized sailfin tang, a large guinea fowl puffer, and a emperor snapper that measured 16-18".
The biggest issue I had with him was sky high nitrates due to his enormous appetite. I solved that using a spare 120g tank with ~300 pounds of sugar fine sand as a refugium. Filled the fuge with kenya tree and palythoas, both of which thrive only less than pristine water conditions. It took the nitrates that were so high as to be untestable
after a 100g water change to barely detectable within a couple months.