Oh there are lots of fish in there.
I grew up only 70km from the glacier that feeds the Elk River, and I've spent a lot of time up at the lakes just below the glacier. In the winter, the water is crystal clear, the clearest I've ever seen in my life. After spring run off however the water turns grey with all the limestone rock flour from the mountains, and it stays that way almost all the way through the summer, then it goes green.
Fishing in those lakes at those times is almost pointless if you're fishing with a cast and lure. The fish just can't see the lure through the murk. Ive been fishing with fish jumping all around me in those lakes and not so much as had a bite. Fly fishers have more success because their fly leaves a shadow on the water, which can be seen from below as a dark spot in the light on the surface, and the fish recognize as food.
Most all lakes in the mountains are stocked with fish, that much is true for the Canadian Rockies at least.
The flour actually does more to help the fish in those lakes than it does to hinder them. In mountain lakes fish are primarily preyed upon by raptors, bears, otters, and other critters. In the turbid waters the fish are safely concealed so they can't be spotted by predators. People out here will actually dye their private ponds so the fish can't be seen to protect them from birds of prey. If they don't then the eagles and hawks will snatch all the fish out of their ponds in no time.