jlk
Aquarium Advice Addict
Hopefully, your fish loss will slow but unfortunately, columnaris (and similar infections) can wipe out an entire tank in a very short period of time. Thats the bad news. Do you have somewhere else you can move your shrimp? I believe this med may be especially harmful to inverts. Inverts generally do not acquire fish diseases so this is not a concern.
In respect to a wc, how do your parameters look? Are they stable?