Hi, I'm Lobex and I'm a challenger Fizz main. Here are some things about me:

-Challenger Fizz Main on NA
-80% WinRate Smurfs to Masters
-Streams on Twitch
-2+ Million Mastery Points

Pros:
-Massive damage
-Very mobile
-Hard to lock down
-Can Engage Fights

Cons:
-Melee
-Poked in Lane
-Squishy after escapes are down
-If Ult misses, you're entire team spam pings you :P

Early Game as Fizz
Allow them to push you in early and try to avoid taking too much poke until level 3. If you're vs melee, you can E + 2 autos for electrocute trade and back off pre level 3. Take trades with your Q + auto + W for electrocute and back off with E for an easy way to wither them down. Recall on cannon waves because when they shove the wave while you're in base, the cannon will tank turret shots for long enough for you to get back to lane without missing too much of the wave.

Try to slow push the wave into the enemy tower and look for roams bot/enemy jungle and top in that order of priority. Sniping the enemy ADC with an ult will most likely ensure your team wins skirmishes. Work on looking for fights around dragon and rift herald and make picks because after all you are an assassin.

Aim to get to the enemy back line by either flanking from the side or flashing through the front line onto the back and wiping their carries quickly. Even if you don't kill both carries, you'll pressure them long enough to give your a chance to win the fight. Watch your positioning though, if you get caught late game, you lose. You can probably burst a carry with just a flash + Q W + E.

Its okay to go Precision/Inspiration/Sorcery secondary, they are all viable and your choice depends on your play style.

Note: Triumph + Legend: Tenacity from Precision is good vs heavy CC like Lissandra.

R + Flash
Hard to react to and you can do this over walls to catch people off guard. This makes your ult go pretty damn far.

E + Flash
Press E once and flash in the direction you want to go when you're coming down from the trident, this is really good for catching people off guard.

Q + R
Extended engage range and good for following up ganks.

Flash + Q + R
Same as last trick but even further

If you have any questions or want to learn more by watching, come by at My Stream

Good luck getting those wins and I look forward to seeing you in High Elo.