Congratulations, seems you have green hair algae. If grown well on a driftwood or rock it can be very pretty, provided it doesn't turn brown.
What kind of glass fish do you have? Not the painted kind I hope.
If you really want to get rid of the hairs, apple snail (big 2cm ones) and Yamato should do the trick, you may have to scrape the remnants off with an old credit card.
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