I put 9 mollies in my 75 gal tank-- 6 dalmation, 2 orange lyretails, and a silver-- and they eat the thread algae in the tank.
Before adding these fish, parts of my tank appeared to be covered in cobwebs. I tried to manually remove the stuff, as it came off of the plants easily, it pretty much "dissolved" in the water, and I knew it would only be growing back the next day.
The mollies are constantly eating it, I'm a little worried they will get overfed. In addition to the algae, they also eat the shrimp pellets and algae wafers intended for my plecos. I had also been feeding frozen brine shrimp and a little flake as well. No starving mollies here
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I also added SAEs which have helped, but it seems like the mollies clean it up just as well if not better.
It has been nearly a week since I launched my attack on the thread/hair algae, and there has been/is no signifigant regrowth that I have had to remove.