Fishman is tanky as hellll so if u pair it w/ gas and Levi shield (which is what I'm gonna do) ur gonna become a literal tank (correct me if I'm wrong)
Use stuff with good mobility and can still damage sea events. Dragonheart is a good sword, draco works quite well because of flight, venom, magma or lightning work quite well, sanguine is the best pick for sea events and same with dragonstorm