Injured weather loach?? HELP

[murben]

I am new to loaches and have recently purchased 2 weather loaches and have them in my 30 gallon tank with 2 goldfish. 1 of the loaches acts/looks perfectly healthy as well as the goldfish. The other loach has recently started resting on top a decoration that keeps him very close to the surface of the tank. I also just noticed a "bare" spot in the center of his back surrounding and including his dorsal fin. It looks like skin is missing. I know they are supposed to shed, but from what I understand, it is supposed to be similar to a snake. Even his dorsal fin is "missing" the skin. I can see the bones where the fin is supposed to be, but it is missing the webbing that is supposed to be there... Please help me understand what may be happening!

[emi-chan]

hmmm, sounds similar to what happened to one of my weather loaches.
if you could get a pic, it would help.

[Diana]

Loaches do not 'shed like a snake'.
This sounds like a bacterial infection called Flavobacteria columnaris.
It has several names depending on where it attacks the fish.
Saddle Disease is when it attacks the dorsal area of the fish. Fin Rot is when any of the fins are involved.
Some things that contribute to this disease:
High nitrates. You have a lot of fish in that tank. OK if they are all under 3", but this set up will not last.
Warmer water. Especially with these fish. Keep the temperature in the low 70s F (low 20s C).

There are antibiotics that will help, but making sure the environment favors the fish will help a lot, too. Do a few extra water changes and thoroughly vacuum the substrate to remove organic wastes. Clean the filter, and remove activated carbon. Then add an antibiotic designed for aquarium use. There are quite a few that are active against most of the bacteria that cause fish diseases, and availability varies in different countries. Get whatever is available. Probably will ba labeled for Fin Rot, as well as other diseases. Follow the directions about dosing, duration and water changes.