Hi there waterfaller1
The thread you are writing in is about two years old, – which may mean that the question you ask regarding how much might not be answered.
I would actually advice you to create a whole new thread, and possibly describe your situation a bit more in detail.
My experience with parosphromenus and illness is that ick is seldom with these fishes, – so you should really be sure that it is ick before treating them – and one or two spots to me is not very much to determine whether they have it or not.
Please describe what the spots look like.
Fish can have spot-like things, or small particles of something that is sitting on them and one can imagine all kinds of bad things which really isnt what it is. Ick shows up as many many small particles on the skin, – like if you dusted sugar on them. Not one or two spots.
Odinium is another thing, – which also looks like small small dust particles, – and yes you could also find that. Probably more often than ick.
I have never seen a paro with ick, – but I have had paros in tanks with boraras which had ick, – it did not spread to the paros. I am not saying they cannot get it – I just dont think they are prone to it.
Anyway, if you wish to have some more comments and advice, please consider making another thread or at least tell us a bit more about what the problem is.
Always also with medication you should consider that medication can really be tricky, – and a small fish as this, the reaction can really be quite the opposite than you expect and hope. So be careful with it.