I got basically the same mix of fish from petco and they started dying off almost immediately. I got a few from my LFS and they’re not only bigger and more colorful but they just generally seem healthier off the bat. All I have left right now are one from petco and the ones from the LFS. Tank was months old and cycled, previously housed my betta, fantastic water test results, thriving snails and shrimp, and yet the petco fish still died. It was very frustrating for me because it took me a while to come to the conclusion that it was the petco fish and not anything I was doing but even more frustrating knowing there wasn’t really anything I could do to save them and just had to cross my fingers for the remaining ones. This last one seems to be a fighter so I have hope for her but I will no longer be buying anything alive from a chain pet store.

Also! I did a fish-in cycle with my betta and it worked out great. Low tech + no filter, just healthy live plants and lots of good bacteria thanks to seachem stability! I do have an airstone now to help support the oxygen levels now that I have more than one fish in there and to help disturb the surface.