Thats a shame. Loaches are quite sensitive. I have just had ich in my one tank, but after a week and a half it has claimed none of my fish, and all are looking better (less flashing etc. one very young pleco even had full on white spots, that have since dissappeared and has recovered almost completely). Part of the success is since i've had it before a couple of times unfortunately i caught the syptoms really early (aswell as knowing the fish's behaviour). Its a nasty disease, sorry bout your losses.