How can I get jellyfish flesh?

So I am a magma-ash mage and I want to know if there is a way I can get jellyfish flesh because both my magics don’t work underwater. Is there like something I can do other than trading to get jellyfish flesh? Thanks.

No sadly

Trading is the only way for heat mages, unfortunately.

if you use self pillar explosion while standing atop the jellyfish it may work

weapons like greatswords/greathammers could help you out here