Here are tips from a Diamond fizz main.
First off Fizz top isn't a tank, not until his 3rd or 4th item, he is squishy before that and excels in short burst trades. So anyone tanky or aa based with a dash or aa enhancer works. Fizz can't duel you with aa's he want's to make you miss abilities or run around you until he has w ready.
Fizz will build mostly ad items, but that doesn't mean he has no ap dmg. Early on the majority of his dmg is ap, so build mr. Spectra cowl is the best for this, but don't finish it. It's passive is great against fizz w dot, it gives you hp regen for the dmg w does (the dot does no dmg, base hp regen on tanky champs is stronger). W dot will reset the passive and you get more heal. After you get that get tabi, because at that point he will start to aa more and get ad dmg items (Sheen, phage). This will reduce his ad dmg a lot and he won't be able to duel you.
Dodge the god damn ult, it's not hard. The missal speed is literary slower than morgana q. Without it he wont be able to insta prock w and cc combo you. Without it he can't go in on you if you have more than 45% hp.
Abuse Fizz whenever he sues e early. It's on 16 sec cdr, he's helpless then. Ask for ganks or start poking him because he is not safe and can't win a trade.
Go juggernauts, they beat him. Juggernauts are tanky and do dmg, as well as being great in prolonged fights and can force them. Champions like
(max w first, q will be dodged),
,
(best choice, counter fizz top completely),
(w negates his burst abilities, also go on him with q and turn e on when he jumps and off when he lands to q him),
(E max, passive is too much for fizz but needs to go tanky items),
(fuck this guy),
(negates aa's and is too tanky to kill while doing a lot of dmg).
Hope this helps. Top Fizz is a result of a un-necessary rework that left his ap build too unreliable and one hit wonder.