It's probably a protozoan infection. Get a broad spectrum medication that treats bacteria, fungus and protozoans. Make sure it is safe for scaleless fish (catfish, eels and loaches). If you can't find one suitable for scaleless fish, use a normal medication at half strength.
Make sure the medication does not contain copper or it will kill the shrimp.
To work out the volume of water in the tank:
measure length x width x height in cm.
divide by 1000.
= volume in litres.
When you measure the height, measure from the top of the substrate to the top of the water level.
There is a calculator/ converter in the "How To Tips" at the top of this page that will let you convert litres to gallons if you need it.
Remove carbon from the filter before treating or it will absorb the medication and stop it working.
Wipe the inside of the glass down with a clean fish sponge. Do a 75% water change and gravel clean the substrate. Clean the filter if it hasn't been done in the last 2 weeks. However, if the filter is less than 6 weeks old, do not clean it. Make sure any new water is free of chlorine/ chloramine before it is added to the tank.
Increase surface turbulence/ aeration when using medications because they reduce the dissolved oxygen in the water.
