Pros

Good burst damage
Almost ungankable
Extremely fun to poke with
Your ult is a freaking shark


Cons

Squishy if you don't build tanky
Prone to get focused
You're gonna need a bigger boat

Taking exhaust help to secure those kills early on and with ignite and fizzes burst its practically a garenteed kill.
I used ghost and flash before but with his mobility the are not that important.
and the rest just dont seem to be so useful for an assasin.

this is the best masteries tree i have tried out the dmg in offence is great plus a bit of defence and hp helps you when you jump in early to kill.

The skill sequence shows how to take the skill seastone trident should be taken up to only lvl 3 because that dmg doesnt grow too steadly so max out playful/trickster to lower it cooldown and increase dmg dramatically also it great for killing creeps then complete seastone trident and of course ult when you can and dash then nimmbe fighter

I dont recommend fighting until your at least lvl 2 and even then carefully when u got them all three activate seastone trident and charge in depending on the situation either after hitting some basics you jump out or use it to finish the fight.
Fizz is great at killing an enemy whose under his turret get your mobs under the turret and and use the combo or ultimate if needed but always leave your jump for escape also since he has little mana calculate if you have enough for the skill sequence or else your stuck under an enemy turret which is not good... :D