Crazy! I Was Reborn as a Unseless Clownfish

Five sea clans, the fire fish, the black sharks, the flying fish, the swordfish and the spirit fish, each had a princess promised to the same clownfish. All five break the engagement on one day, in public, and he becomes the joke of the whole sea. He has been the failure of his own clan for twenty years, unable to take human form when the rest of them could, and they have looked at him that way for most of it. The person inside is not a fish at all. An ordinary man woke up in that body and has been living in it since. To settle the five clans down, the clan chief sends him out to the abyss fishery, where the beasts are thick and nobody is expected back. There he finds that he can devour what he kills and take its strength into himself.