Yeah, I agree. With the proper protocol, freshwater to freshwater works. The emphasis though is on maintaining good water quality and not over feeding. Hungry fish are healthy fish. I think making the presumption that your feeders are diseased and acting accordingly is prudent. Just elevating the salt to .6 - .8% in quarantine makes a big difference. Also, with all goldfish, feeders and fancy, flukes are a problem and usually the last parasite standing. Prazi makes sense, but Oddball has it down and has seen enough feeders to know the difference between a batch that is good and one that should be avoided.