How can you tell a fish in good health? You're not a vet, or neither you can run test on the fish at the time you buy it, assume you buy it in person. Best you, or me, or most if not all the fish keeper can do is tell by looking at it, that it doesn't look skinny. Once you get it home, and it doesn't eat, acting funny, then that's when you'll get worry or panic... Wonder if it's your husbandry or if it's the fish that's not in good health. And if you buy it's on line, then forget about it! All you see is a picture! So, does reputation mean anything now?