Morning, well I can't really give an update, I may go down in a bit and turn the lights on and drop in some food to get an idea of what's going on - I don't like doing this though, I feel it messes up their daily cycle, but it is the only way to see what's going on.
Looking into the tank I can see a couple that seem to have increased breathing but I don't think it's as rapid as it was, and they don't seem to be as jumpy as they were and are more active - providing these are the same ones. The real question is though, is this the eSHa clearing up some infection, or whatever they don't like in the water dissipating. In any case I think the best course of action is to neglect water changes and keep treating with the eSHa for the time being until the fish stablise, if they do. Given the size of the tank, the light stocking, the number of plants and the fact I've stopped adding fertliser it should be fine without a water change for a good length of time.
I'm not really sure about these fish's history - I've read a lot of them are wild caught and they came directly from a wholesaler so they've never been in tanks in a fish store but that's as much as I know. As you say they may not be used to tap water but given these symptoms didn't arise in quarantine when I was gasing off the chlorine its more likely to either be the water conditioner (which i admit is old and probably well out of date) or something once off that arose in the tap water. As I say the water conditioner is old, but it hasn't affected the other fish, or upset the filters, so it is working, and my shoal of Harlequin rasbora are relitively new, so it isn't just a case of the fish being used to it. There is so little left it doesn't bother me just chucking it just in case and I have Seachem Safe to start using - but I find it all a bit hard to believe.
I don't use carbon in my filters, don't really believe in chemical filtration. However, for that reason I do still have the carbon pads that came with the filters, so could easily give this a go. It's something I should really buy, but I do have some somewhere. It always seems very wasteful never really knowing how much is needed or when it needs replaced. And nobody seems to know how much to use, or how long it lasts etc And generally the plants should take on the role of the carbon I believe - they'd certainly suffer long term with its use. However, as a way of eliminating water quality issues it's definitely worth a shot.
The plecs visibly appear fine, I'm not sure I'd notice heavy breathing on them though?? What I can say is it's very easy to get a good look at their gills when they are feeding on the glass and there is no sign at all of inflammation or infection.
So plan of action I think, is
1)Keep Watching And Hoping
2)Treat with eSHa and avoid water changes until things appear normal
3)Change water using an alternative product
4)Add carbon if problem arises again
There is the small problem though that it may be an infection that is clearing up, but that if they find the water changes stressfull, may flair up again. And then I'm back to the same cycle and not really knowing whats going on. Fish, who'd have them, and I love these little guys, they have so much character.