This is a build guide that I find to be very effective with a lane fizz, either solo top or middle. The key to this fizz is getting alot of Ability power, while also having a decent attack speed, to maximize the number of hits on target, especially during that 5 second window during your active on Seastone Trident.

You begin with your first item depending on who you think you will be going against. If it's someone with a lot of ranged abilities that are skillshots, start with your boots, if it's someone with a lot of attack damage or non-skillshot abilities, it might be better to start with Doran's ring or the Amplifying Tome, so you can match their damage output. Always rush the Fiendish Codex off the bat. This will give you much needed mana regen and decent cooldown reduction. After the Codex it's best to finish off your shoes with the Beserker's Greaves to ensure that you get the most hits in with your Seastone Trident (W). Then once you have that it's good to get the Sheen, this will help you take down minions faster, by using your abilities and also will help you take down turrets faster by using Seastone Trident (W) and Trickster (E) while attacking the turret to proc the Sheen unique that amplifies your damage by a lot. Then you want to work on getting the Deathcap, this will make your abilities do a lot more damage and will amplify the AP from the items you already have and will have in the future. After you get the Deathcap, it's best to get the Lich Bane, this will essentially make you a hybrid champion, since everytime you dash (Q) to your target you can auto-attack them once to proc the Lich Bane and then hit your Seastone Trident (W) to proc it again, and if you are able to kill the target it's best to use your Trickster (E) for that third technically critical hit, since with the Deathcap and other items you should be doing around 400 attack damage for each Lich Bane proc. After you've got Lich Bane, you want to immediately go for finishing the Nashor's Tooth. This will give you a much higher attack speed and reduces your ability cooldowns so that you can escape easier with Playful (E) because it should be on a 4-5 second cooldown at this point and will also give you a chance to proc the Lich Bane more often. After you've got the Nashor's Tooth you will then want to get Rylai's Crystal Scepter, to make you more durable in a team fight and also gives you the ability to slow targets with your abilities. After you've got the Scepter, it's best to go for the end game item that will allow you to dominate anyone in a 1 vs. 1 situation, The Hextech Gunblade, it will add to your overall attack damage and also give you a ranged slow. The Lifesteal will also drastically heal for every Lich Bane proc and the Spell Vamp, will allow you to win those narrow situations where you are low and being chased by someone else who is at lower then 50% health and you have your ultimate. You can easily Ultimate them, then wait a little to Dash (Q) to your target and burst them down while they are still being knocked airborne by your shark, and the Gunblade will ensure that you will heal up a substantial amount of health during this manuever so you won't be easily taken down if they happen to survive the ultimate combo.