plecoperson
Fishaholic
They have lots of tropical fish, and are probably far less diseased than Pets at Home, (although, the only problem i saw there was a larger goldfish stuck behind the pipe in there. It was alive) They also do reptiles, so I'm very hopeful
Just curous as to what grounds you consider that diseased?
and be especially aware of anywhere that sells reptiles...just because they sell specialist pets doesnt mean they have specialist knowledge!!!!
Danios can tolerate cool water but cant really be kept in a tank that size, neither can the minnows. they are very active fish.
a betta with a GHOST shrimp and a couple of ADFs could be a good combo but make sure you do your research on them first especially the ADFs. Most pet shops won't know much about them, if even if you find somewhere that stocks them.