There's a company called Finless Foods which plans to use cellular agriculture (aka "lab meat") to create vegan fish products.
Finless Foods is an early-stage biotechnology company whose mission is to develop and mass manufacture pioneering marine animal food products for human consumption. Our objective is to create seafood sustainably using scientific cellular agriculture technologies, which will provide a cost-effective and healthier appetizing alternative to conventionally-caught and commercially-farmed seafood.
And in March 2018 Wild Type joined the industry with plans to grow lab-grown salmon.
There are other companies like Gardein which are creating vegan fish sticks from soy protein, vegetable fats, and starches.
And getting even closer to whole foods, Sutton and Sons (a London pub) recently showcased their vegan "fish and chips" (Video on Facebook) made from marinaded banana blossom, seaweed, and samphire.