The mola-mola, or ocean sunfish, is one of the largest, dirtiest, and ugliest fish in the sea. But it IS the best at something: it lays the most eggs of any vertebrate - three hundred million at once! Fish Eggsplosion! So why aren’t the oceans crammed with them? Well, not all of the eggs get fertilised, and their tiny young are easily swallowed by predators. Eventually only one or two reach maturity. Phew!

More information:

nationalgeographic.com/animals-with-most-offspring-fish-eggs-reproduction