Hmm I need more details. How exactly is Kaido's devil fruit being a fish model when we already saw his Oni and Dragon form?
Does it mean either his oni or dragon form is fish related or that he has another devil fruit? But the gorosei said Blackbeard was the only one in history with the ability of eating 2dfs without dying, so it wouldn't make sense
I hope the relation between his Oni and Dragon form is clarified
On the other side, I guess Oda decided to delay the Ace flashback for later