understood, but if you find a reliable LFS then the survival rate should be very good. Find one you trust and that actually acclimates their livestock properly before selling.
I have no worries about the fish we got last weekend, just picked up the same combo of yellow tank and blue hippo both were at the store for over 14 days and are both eating pellets/frozen and flakes after 2 days. I am hopeful they will be healthy for the long term but you never know.
good luck