Will texture of fish cooked sous vide change, when cooking times increase?
Yes!  Cooking low temp absolutely degrades texture of fish.  I can't imagine that you would want a piece of salmon cooked for 10 hrs.  It would be mush....cooked, safe...but mush. Most fish...probably 20 minutes or so.  Any fish should just be cooked until done.   No more.  Otherwise texture is compromised and off putting.