well, as you may have seen already, fizz is a champion who deals a lot of damage in a really short time, its hard to master him, but when one does so, he is unstoppable.
I've mained fizz since it went out, and I've tried many builds, but this one here is the one that has been more useful to me. i got 13 straight wins with fizz and in 12 of them i got to legendary.

this is my first guide, so please dont be mean :P

PROS | CONS
great harassment | squishy
massive damage | dependent of gold
great chaser/escaper | gets focused a lot :C
when fed, can kill almost anyone
great starting fights
AOE damage
applies grievous wounds

well, you might think: why the hell should i get a lich bane first?! but it is really useful. it boost your W and Q together and become an even more powerful blow.
After that, if the match is going good for me, i get the mejai's soulstealer, the AP that book gives is amazing(:
After that i get the Rabadon's Deathcap, i get an AP boost with that, the damage output made is enormous! after that i usually get Rylai's crystal scepter, thnks for the slow after your Q, they wont be able to escape, plus it gives you more survivability.
then, if the enemy team has more AP than AD, i get the Abyssal scepter, it gives magic R. and lowers the enemy Magic R.
And finally i get the Morelo's evil tome, it gives cooldown reduction and gives mana regeneration, and good AP. you can change the abyssal scepter for something else depending on the situation or in the enemy team.

i pick this skill sequence, because the main source of damage will be your W , and at early levels, using your W with your Q will make an excellent harassment.

Ignite: this is one of the most useful summoner spells for fizz, this plus the damage your W leaves, will ensure a kill when the enemy champ still has some HP left.

Flash: this is a great escaping method, and chasing method as well, when you need a little less distance to throw your shark or use the Q. because the E of fizz cant jump all the walls, and some of them only with practice, this will be useful for escaping through the jungle

you can use a lot of other spells, but the more viable are:
Surge
Cleanse
Ghost
Clarity

well thnks for reading this guide, if you liked it, rate it and comment, if you didnt, do it as well, i want to know how to improve the guide, and the presentation of it(: but dont put stupid immature comments