Feed or get eaten by Fin the shark man

Fin was an experiment when he was a baby, but he had a disability where he could not poop, because of that, he was born with special stomach acid that disolved anything that went in his stomach. Fin would always be hungry, he would eat ANYTHING, even non edible things. Nothing could poison him or get him sick. When he is really hungry, his stomach acid would stop disolving things for a period of time.