With excellent plant tank conditions, moderately to soft KH's, good acclimation, 82F and warmer temps, well fed, they do exceptionally well, maybe 5% losses at best.
Some batches seem to vary , but over all, you cannot tell till it's too late and with being a fish pathologist, it is very difficult to see if it's the fish or you and somethign you have done.
So, with that in mind, the above list will help you isolate the potential causes much better, using the 5% or less as a guide for successes.
Slow acclimation is really critical for many species.
Take your time.
Feed well, they can almost 2x their size with good feeding in 1 month.
Ick is common when they have NH4/Cold temps etc.
I have 600 in a client's tank we have lost less than 5% and these came directly from the wholesalers....not quarentined fattened up fish in LFS.
I have lost them in past many years, but just focused on common sense things to minimize fish losses.
Large frequent water changes, I did that prior to having fully planted fish tanks. Good food, I learned that when breeding fish.
Good acclimation: slow steady acclimation, this goes without saying but even still......many folks...........
Smaller the fish, the more frequent the feedings.
Warmer temps and softer water will help many species from such waters.
Varies depending on species etc.
Try applying these basic things.
Then see if you lose many fish.
My bet is will not and if so, it's due to one of those or incompatible inhabitants.
Regards,
Tom Barr