So I have a 90 gallon tank with Discus and pleckos and some other small fish we do have wood for the pleckos to eat and we feed our discus bloodwors and brine shrimp in the last 2 weeks we have gone from 3 discus bieng black and not eating much and now we have some who have died who didnt look black we asked around in a store in the citys for medication to help they gave us something called (kananycin) hope that is spelt right? The directions given were to do one dose every five days with 25% w/c btw each dose after doing both doses and even taking out about 30% out instead and adding more RO water with conditioner we still have pleckos dying as well not sure what to do we are going tom to get a test kit for water and get our water tested as well any suggestions as we cannot figure out why this is happining our usual water temp is 86 if that helps?? Oh i forgot to say we did buy and add that blue rapid ick cure about a day ago?