With one bandage on his cheek/neck compared to Luffy, Zoro, and Sanji being all wrapped in bandages. And most of them were sustained when Who's-Who was gayopsing him with posse.
That wasn't "Fish-Man rage mode" Jimbei, that was just a pissed off Jimbei. Look at the eyes.
For comparison, here is a pissed-off Arlong's eyes.
This is Fish-Man rage mode Arlong's eyes. Note how the pupils go vertical.
Notice Jimbei after breaking Who's-Who's with amped-up CoA did not do that.