Just because they apologized doesn’t mean that the joke suddenly disappears but they can show that they understood their mistakes by saying sorry since that’s all you can really do. But sometimes, saying sorry isn’t enough. Yet again, this is what I personally think.
Because the fish was dying it represented the grenade without its pin.Therefore you have little time to throw it before it explodes and in this casethe fish was suffocating and had a set time before it died.