Clown Loach - HELP REQUEST

[Teestee]

Hello everyone.
I have x2 clown loaches in an established (6yr) 120L tank.
Weekly water changes alternating 25% and 50% every fortnight - never any problems with nitrogen cycle.
All water changes treated with Tetra AquaSafe, Tetra Easy Balance, and API Aquarium Salt.
But the larger Loach has developed a flaky appearance at the base of its dorsal fin and has stopped using the fin.
No obvious signs of parasites, ICK, etc.
Any help diagnosing and guidance on treatment.
Photo enclosed.

Thanks, in anticipation.

[plankton]

Welcome to the forum.
Unfortunately the clown doesn't look too happy.
How long have they been in the 120l tank and how big are they?
They should really be in at least a 5' tank with at least 3 more clowns. (Info, not having a go)
The gravel doesn't look smooth, which it needs to be to stop them getting infections through their barbels.
What's their diet, and what are the water parameters exactly, including hardness and temperature?
It actually looks like something akin to "hole-in-the-head" (HITH) disease, so will need treating with something like Waterlife's Octozin. (It isn't exactly that, but it's normally caused by the wrong diet in loaches)

[Lo1]

It is difficult to tell from the photo. However, it is likely to be slime coat or skin problem caused by external bacteria.

[Lo1]

This is a good source:

https://www.jbl.de/nl/blog/detail/247?country=nl


This one has 500 photos, the disease names are in German, once you marry up your disease with a photo, just Google translate it:

https://www.jbl.de/nl/online%20hospital ... country=nl

[Clownman]

Loaches are sensitive to water quality, raise the tank temp a couple of degrees, and see what happens.

Also, why are you using salt and easy balance? I'm not a huge fan of messing with water chemistry, it's near impossible to get it exact every time, and with water changes equating to 75% every two weeks, there's a lot to go wrong.

Loaches are very sensitive to anything that goes in the tank, medications especially, so only dose half strength.

[Martinspuddle]

Greetings & welcome to

It's either what @plankton said or some sort of Lymphocystis.

What are you feeding them?