Kisame wasnt at 30%
Remember way back when kisame and gai fought??
Well kisame used 30% of his total chakra in that transfer body technique and even then created a sea just from chakra itself (which is on par if not better than what the 2nd hokage could ever manage)
Gai then wiped him out with 7 gates phoenix attack, but kisame had made clones, and it states in naruto that clones distribute chakra evenly, so when naruto makes 1 clone, his chakra is half.
Kisame made 3 clones to trap the 3 kids.
1 clone = 15%
2 clones= 7.5%
3 clones= 3.75%
Kisame only had 3.75% of his total chakra, and managed to fight gai evenly if not better, and also use a very strong ninjutsu.