On removing an ornament from the main tank to put into the QT ( which is now housing some new harlequin rasboras
), I noticed that one of the pygmy cories (which I've had for 5mths) had been hiding inside the ornament. Although there is some noticeable variation in size and colour of my pygmy cories, the one that had been hiding inside the ornament looks particularly small, if not smaller than he used to be, and rather "washed-up" like he's a black garment that's been through the washing machine too many times. Lately, I'd had trouble finding all 6 at once, although usually managed to do so - but now wonder if the cory that has been hidden regularly in the corner near the heater has been the same one and this one, and that he has possibly been making a habit of hiding inside this ornament.
This evening, he did move about a little for a swim along the front of the glass which is an improvement on yesterday - but, on inspecting him, his barbels look very short (although this could be that he just looks smaller all over), and I wasn't convinced that one of his eyes was functioning properly (although I can't be certain about this). There is some redness inside near his vent which I think looks like some red poo is about to come out - and could be accounted for by red-coloured food, if indeed he has actually eaten anything.
I'm not able to be very specific - apologies about this - but wondered if anyone had any suggestions for converting him from 'surviving' (barely) to 'thriving' once again? [This is where a dose of aquarium salt worked wonders on goldfish but I know isn't appropriate for cories - and not when the other tankmates all seem fine (touchwood).]
I do weekly water changes - the new siphon is quite strong in comparison with its predecessor and so the water changes have tended to be 40% lately. Water parameters seem to be consistent with ammonia and nitrite at 0, nitrates never higher than 15, PH 6.4, water is very soft but some Tuffa rock is keeping it from being overly so. Substrate is Unipac tana. Food is a mix of good quality flake and micro pellets, with some occasional Tetra Delica daphnia - the cories have been able to get more than their fair share of food in recent weeks as the x-ray tetras have been less interested in food than usual (albeit behaving fine) and therefore more has been falling to the substrate.
Thanks in advance for any suggestions you can offer.