Codroma is a favorite by the Venetian locals (it was recommended to me by my parents). Their dishes are carefully executed Venetian traditional recipes. Spaghetti al nero di seppia (spaghetti made with black squid ink sauce) are a must. Their "fritto misto" (mixed fried seafood) is also amazing and delicate. This is a real word Venetian restaurant (reasonably priced, not posh interiors). Their staff is also very kind and willing to explain the recipes. Go there with confidence.