Are there any fish substitutions? I have found subsitution for everything else except fish.

There's a brand called "Veat" that is vegetarian (it has whey). There are also some Asian brands that taste amazingly like fish and even a faux shrimp that has a shrimp like texture.

There are recipes for faux tuna salad with tempeh and sea weed and such that are good.

I'd be careful of some of the asian brands, specifically if they come from taiwan. Apparently there has been an issue with 'vegetarian' meat products from taiwan being not quite vegetarian.

I never liked fish myself so I don't search out substitutes but there are a lot of seaweed recipes that will give you a bit of fishy taste if you want it.

I don't know if it's what you are looking for, but I just bought "Vegan Comfort Foods" yesterday and note that it has a fake fish stick recipe made from tofu.