Hi Bryan. You should be able to find most information about how to keep parosphromenus species on this page, theres a lot of information. Also you might want to visit our facebookgroup, you can find it (and the group on facebook) by following the link on the frontpage here.
Its difficult to give you much advice on your questions, – of course there are many things which can be the problem, – its a delicate species which requires special water conditions, – and do not thrive in ordinary high light, strong current tanks, – but since you do not describe what kind of tank you have them in, its difficult to answer. And I think first of all, I would recommend you search all the information on this homepage and maybe that will give you an idea.
The forum here is unfortunately not so active, – most of our activity is happening in the facebookgroup. So maybe see you there 🙂
Kind regards Helene