Okayy. Fish source also might be an issue. Certain way they catch the fish will also result in the fish survivability. Put it this way, (i wouldnt disclose their shop to protect their identity , afterall is their livelihood) i bought firefish at LFS A for 5 time. All their firefish wouldnt last more than 7 day in my QT, even when they are feeding. Not only firefish, out of the 30 (estimated) other fish i bought from them, maybe only 5 survive. Last time i bought from LFS B it pass through my 21 day qt and it lasted for 6 month before it succumb to starvation as it cannot compete for food in my main tank. Ultimately It really boils down to how they catch their fish, hear say some lfs sources use cyanide to catch fish. I declare, rumour ah. [emoji1] So a piece of advice where to buy fish, either from reefers. Or.... from lfs u know that nv uses cyanide , which could be done if you check with other reefers.