From personal experience, in the disease categorey, this is 99% on the fish keeper. Sure your fish can get diseases no matter what you do to keep the feeders healthy... It happens. About all of the videos on YouTube of people feeding live feeder fish show them going straight from the plastic, oxygenated bags from the LFS, to the fish tank. IMO this is why there are so many doubts on feeding these goldfish, because people like that have their fish killed and wonder why, blaming it on the risky feeding of live fish when they are the ones that neglected to quarantine the feeders to reduce the risk.
I was not trying to say feed live all the time but i personaly believe it should be a part of diet for sure ....As far as dry feed personally hikari all the way ive tried others and the quality just is not there IMO and Just mine .....When you keep big fish even tho you want to give the best dry's available you have to look for good and great fillers such as cut bait tilapia shrimp and others i could empty a one pound bag of Massivore daily into just one fish witch is not going to happen ...There is no reason to flame this guy even if he is a Koi breeder and telling people you can't feed live or your fish will wither away is not right either just throwen my opinion and guess what i can
Oh and last time i checked lions don't always come from Zoo's