Trois complains there are fishes in the 40cl drinks. Maybe you could mix him a drink without a fish in it?
You need two glasses with drinks on them. One is on the cocktail bar counter. The other one can be found from counsil floor (pink key in the elevator).
Great. The other glass has a fish in it. Trois was right. Now that you have both glasses go to the blender. It is a skippable minigame of getting most of the drinks into the blender without the fish.
Serve the cocktail to Trois.