African Cichlids like hard water, but of course will only work with their conspecifics because they are very aggressive. Central American cichlids (convicts, firemouths) can also tolerate it very well.
On the peaceful side, mollies can even adjust to brackish water, puffers, monodactilus.
Fish that don´t care about ph (will adjust to varying conditions) include danios (various types), barbs, gouramis, paradise fish, etc.
You can lower your ph via driftwood and peat moss, it´s not that difficult!