I've seen a lot of Burst Fizz builds, and with his passive being an on hit DoT, I decided to try and build an on-hit Fizz. I'm still experimenting on what items to get, but, I think that this is a pretty solid build so far. I've had only a few chances to play this build outside of Dominion. This build doesn't have a lot of sustain early game, but I'll touch on that later.

I open with a Malady because it adds AP, and attack speed. This will be very helpful early game for minor skirmishes in lane. Then build a Nashor's tooth. This will add cooldowns, AP, and attack speed and will help a lot in a fight because you can use your "q" and "e" more often if need be. Then Rylai's for HP and AP. You will be able to burst fairly hard on squishies and your burst will close the gap so you're in range for basic attacks. I then build Wit's End for the on-hit damage and attack speed. After Wit's End, Bloodrazor will help counter the tankier characters.

Before lv 6 you'll open with "W" into "Q". When you're near them, basic attack until you think you can win the engagement. If not, just use "E" to escape.
When you're lv 6 open with your shark and do the same.

Always stay behind until your tank initiates a team fight. Or, initiate with your ult and wait until the fight starts. Attempt to pick off their support, then carry, then tank.