I usually don't cross post stuff, but I wanted to see what you guys in this
ng might think about this:

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My 6 clown loaches are doing some strange stuff, at least to me. I have a
75g planted tank and my 6 clown loaches like to go to the very top of the
tank and "root" along the glass just above the water line. they make a very
loud popping, slurping, clicking noise when they do this. the 2 big
angelfish and rainbow fish come up and watch like something strange is going
on, but they do not do this. i have looked where they are doing this and i
cannot see anything on the glass they could possibly be trying to eat. what
could they possibly be doing? is this an indicator of a problem in the
tank?