Hi..

The entire genus Ahyosemion. And every other genus of
killi. I'm not aware of any that can not be kept in hard
water (albeit they MUST breed in soft water). There are
hardwater killies (pupfish ans such) that will definitly
die in too soft of water.

It wasn't my purpose to declare each killi to be a soft
water fish.

Long while buddy! Years and years. Tetras, barbs, dwarf
cichlids, angels, tetras, they all do fine long term in
hard water IME.

More or less *long* buddy!

--
cu
Marco, coming from a different fish keeping tradition..