Hey Iam stuck on ff 9 i got to disc 3 but iam stuck at ipsens castle when I get to the boss. That big zonbie Fish I hardley take any damage of Zidane was my strongest character but on the fish he takes 44 off of him.

I used Grand lethal twice on it and I still Couldent beat it any help whould be grateful.

I assume you're talking about Taharka.

Stats-

HP: 29, 186
MP: 1, 776
Level: 46

Weaknesses: Bird Killer, Fire, Wind.

Basically, keep using move with those attributes. There's no point in attacking with physical attacks when it curls, because they're pretty useless. Have Vivi use Focus then cast Firaga repeatedly. Steiner with Flame Sabre and Add Status will cast heat on Taharka and make it a lot easier. And just remember to keep healing.

I assume that you might still have the character's weakest weapons on. As Ispen's Castle, the lower the attack value the more damage it'll do. But this doesn't work with the boss, equip your most powerful weapons and take your strongest physical attacks along with Eiko and you should do fine.