How to carry as fizz

Imo i feel like he doesnt do enough like sure he will kill your adc in about a second but what if the enemys have like a fed yi hes gonna kill ur whole team and once fizz 1 shots someone even if fed he then has to wait for his cooldowns to be back up while the enemy yi needs to wait about 0.2 seconds to do his dmg then he keeps going without cooldowns unless u count 1.50 as a high cd