so "Blue Shrimp" (Crevette Bleue) eats the algae right?

Answer 1

Yes, but don't expect them to make much noticeable difference to the tank - get them because you like them, not as an aquarium tool. They are also scavengers and do need to be fed pellets and spirulina wafers, especially if your tank isn't full of thick algae and/or live plants.