Fish Health In My Tank

It would be helpful to get others' views on this.

In my main tank, I have 3 remaining male x-ray tetras from the original shoal of 6 (age 4), all 6 of the original shoal of harlequin rasboras (age 3.5), and 4 of the 8 recently purchased neon green rasboras (3 months). They just don't seem to be in optimum health, despite water testing pre- water changes (1 x 40% plus 1-2 x 10% per week) and water being consistently at 0, 0, 20 for ammonia, nitrite and nitrates. Problems are as follows:
* one x-ray tetra with cloudy / cataract-like eye which culminated in a pop-eye type situation, seemed to burst, leaving a flap of film over the eye which disappeared and left the eye seeming very flat and possibly blind, but the pop-eye situation has now recurred
* another x-ray tetra which intermittently has an injured eye, possibly through sparring with the former
* a harlequin rasbora which has been getting skinnier for many weeks now and who I haven't seen eating at all - he swims towards food and mixes in the feeding frenzy but doesn't actually eat anything, even when it falls or is put in front of or beside him and even when it's the favourite of garlic-infused brineshrimp; otherwise, his behaviour is fine albeit less active
* a harlequin rasbora which seemed to have scraped itself on something, this evolved into a hole-like ulcer not dis-similar to the female x-ray tetra who had this recurringly, then healed but looks as though it may be recurring
* one neon green rasbora with a raggedy tail (slightly torn, slightly speckly but never evolving completely into a fungus or whitespot) - this fish seems to have taken command of the tank, occupying the middle 60% width of it, with anyone in her space being chased away
* one neon green rasbora with the top portion of the caudal fin missing, and only a partial bottom portion; this looks as though it's just growing back when it disappears again
* one neon green rasbora with a non-full tail (ie the upper and lower portions of the caudal fin are pointier/thinner

The x-ray tetras' problems might be accounted for by a combination of sparring and becoming older. Reluctant though I am to admit it, the harlequins' problems seem to have coincided with the neon green rasboras' arrival, whether due to reduced swimming space in the same upper echelon of the tank and/or the greens' comparatively lively behaviour +/- one green's tendency to nip. I've witnessed a few nipping episodes and I'm trying to recall whether one of these was caused by a harlequin. Last week, I had a harlequin peck me quite strongly / with intent during the main water change, then again shortly afterwards (if it was the same one); in the past, they've been inquisitive but have never bitten, let alone with force. The greens' health situation was like this pre-move from QT to established tank but has never really improved. [In contrast, in the QT, all 4 "newer" (but of the same batch) of neon green rasboras are in optimum health, with tails all intact; they seem to get on very well, with no one fish being in command or chasing the others, and generally seem very content in their QT.] Any further thoughts for likely or potential causes? The only "anomaly" I've noticed is that KH and GH seem to have been lower than usual (KH=1, GH=3), although PH remains the same at 7.5 (water company seem to artificially increase it).

I have 3 types of treatment - medication which would require moving the fish to a hospital tank and which I haven't been using (which is currently in use as a QT, though), Melafix (aka tea-tree oil which I have been using in 3-day rather than 7-day doses as I've been a bit wary due to others having problems with it) - this seems to result in temporary improvement of the various health problems above but these recur after treatment is ceased) and Easylife Voogle (which, on the few occasions I've ever used it, seems to result in the hole-like ulcer developing an almost immediate saprolegnia-type fungus before falling off and healing starting but no other visible improvement for any of the other health problems). I also have catappa / Indian almond leaves in the tank.

Thoughts on potential explanations or solutions welcome (aside from the temptation to allow the new neon greens to inhabit the QT as a permanent home given that they're doing so well in there!). Thanks. 

Melafix is not a terribly good medication. It's more like putting dettol on a cut - good to stop it getting infected but useless if the cut is already infected. I would try something a bit stronger (eHSa 2000 or Myxazin)

Ah, I'd forgotten about the snails.

I know that eSHa 2000 does not kill cherry shrimps because I had to treat my betta for finrot a couple of weeks ago. And it doesn't kill pest snails (they'd survive a nuclear holocaust  ) or Malaysian trumpet snails, but nerites are a whole different kettle of fish. Or snails.

I don't know what to suggest. Anything that won't kill nerites probably won't kill any bugs either 


As a side issue, eSHa 2000 and Myxazin don't harm the filter bacteria. It's antibiotics that do, and we can't get them in the UK without a prescription.

How about putting your nerites in a bucket with an air stone and some filter media while you medicate the tank? Would probably require water changes to be on the safe side, but better than nothing in an emergency.
Also, will be obvious to Mr FCMF that it is only a temporary arrangement, rather than a new tank. 

Thanks, all - very helpful indeed. 

As a side issue, eSHa 2000 and Myxazin don't harm the filter bacteria. It's antibiotics that do, and we can't get them in the UK without a prescription.

That's great news - I was convinced they did, so that's welcome news.

I didn't like to suggest that, knowing Mr fcmf and another tank (he's like Mr Sue). I have used the nerites in a bucket option as well. Put something over the top to stop them climbing out and if you don't have a spare heater, put the bucket in the warmest place you have. You will have to do daily water changes.
Once treatment in the tank has finished, do a big water change then water changes every day. Run a couple of batches of carbon in the filter. The water changes will remove most of the medication, and the carbon will get rid of most of the rest. Finally, run some Polyfilter http://www.arcadia-aquatic.com/product/poly-filter/ in the filter for a few days. This should remove the last of the med. Yes, it is very expensive but I always have some in the cupboard.
Then put the snails back.

Mr FCMF recoiled in horror at what would be involved, blurting out "you'd be better setting up a new tank purely for the snails...", then immediately retracted that comment when he saw my face transform in delight. Argh - wish I'd managed to contain myself better! He then spotted me later on with a tape measure and I've been given a stern warning not to even think about this which of course I can't help doing...

A second tank is unfortunately a definite no-no. I'm also not prepared to put my snails at any risk at all - I hadn't appreciated just how fond I am of them, in particular the first one I got and with whom there's a definite rapport.

The new fish have now completed 3 weeks of quarantine and I had intended for at least the full 4 weeks. Therefore, my options are:
* move them into the main tank a week early, but run the risk of doing so causing further problems in the main tank, but move out those fish with problems for medication in the QT
* wait a week and move them into the main tank as originally planned and hope that the fish in the main tank don't deteriorate during that intervening week - the situation has neither worsened nor improved, albeit the skinny harlie hasn't eaten anything for possibly a couple of months now and is getting increasingly concave to the extent that his tail is almost larger and more robust than his body (not sure he'd actually survive medication - if anything, he'd be better in a tank on his own and encouraged to eat in there but without medication)
Dilemmas, dilemmas...

Thanks, Matt. I had an inkling Skinny Harley was on his last legs fins, having not eaten for 2 months maybe and looking more gaunt daily, and certainly wouldn't have survived medication if transferred to the quarantine/hospital tank along with the other fish requiring medication, and thus I delayed the quarantine > main tank transfer. True enough, this morning he was on the bottom, listing over / bent and spiralling. I had no option but to perform euthanasia. 

I'll set about the tank transfer for the other fish later on today.

A plan is up my sleeve for this (unbeknown to Mr FCMF), but it will require a massive clear-out operation on my part which isn't do-able overnight...

Thanks, @Littlefish.

After faffing around with filter sponge to attempt to seal any potential gaps at the side of the filter in prep for the new neon greens given their expertise at getting stuck behind filters, I've now swapped some fish around - the 4 new neon greens are now in the main tank and have been accepted by their tankmates from the outset and been settling in well from within a few minutes of their move, while the double-pop-eyed x-ray tetra and the almost-no-tail neon green are in the quarantine/hospital tank with eSHa 2000. The raggedy-tailed neon green seems to have mended, so this just leaves a neon green with a white spot on its lip that I would like to medicate but he's become wise as to what I'm doing and escaped capture and so I've abandoned that for today.

Fingers crossed things continue to progress in a positive manner with all your fish.