Loaches Online Forum

There is a thread concerning something that sounds similar posted on this site a year or two ago. Im not sure if what your fish has is the same condition, but it might be normal "shedding" that occurs in hillstreams. Do you have any pics that show this?
One thing you do have to worry about with hillstreams is that they sometimes don't ship well and can die up to a week after coming in. I suspect that they are deprived of oxygen during shipment and don't recover. This seems to happen less than it used to, but it still can happen. It happened to the first gastros and sewellia I purchased.
Hopefully, yours will be okay. If they are feeding, then they should be okay.
Keep us posted!

I felt like experimenting a bit and added another internal filter. The male and female are out a lot more now.

Currently running:
AquaClear 50 (200 GPH)
Aquatop IF-450 w/ Venturi (119 GPH)
Jebo AP2100F2 w/ Venturi (400 GPH)
Rena Air 200 on high

The male seems to hang in the airstone's bubble stream & the female is out more, usually taking cover under a driftwood. She looked like she was feeding on the walls, cleaning some of the algae off of it.

I'm wondering if this might be too much filtration?

They seem to be more active now than when I only had 320 GPH, but 720 GPH seems a bit much for a 20 gal long.. over 35x turnover. I can take out the Aquatop and put it down to 600 GPH or just leave the Jebo so it's exactly 20x turnover, if that will be more comfortable.

The Gastromyzons are definitely enjoying the extra current. Minus the G. scitulus who's hiding in a cave, they're all scaling the glass like they're on a mission!