Does resting fish before serving affect its texture or taste? More and more recipes seem to turn up that tell you to rest fish before serving. Not for very long, but still. That seems not right to me. You rest meat to reabsorb juices and relax,so it seems more tender. And to even out temperature differences.

Fish is a completely different kind of "meat", and I don't see why resting would help here. For one, the cells have less tough walls, so it is tender anyway. And the temp issue seems less important as well, being less dense than meat.

You could argue that dense fish flesh, such as monkfish, is more like meat, and therefore resting is necessary, as I have heard. But that seems a very dubious reasoning to me. But the chefs on the same level as Ramsay propose to do this...not that these chefs are necessary right and up to date with the WHY's of what they do, of course.

Would resting fish change the its taste or texture in any noticeable way?
Would resting fish change the its taste or texture in any noticeable way?

No, in short.  The only mention of 'resting' of any fish is from the Lophius genus (aka Monkfish, Angler fish).  It is suggested to allow the monkfish to rest if you are going to slice it before serving to reduce the amount of liquid released.  

I would suggest to portion the fish before cooking, and serve asap after cooking.

I think mainly the term 'resting' for fish is inappropriately used, as the fish is actually undercooked and the carry over/residual heat completes the cooking before it is consumed.