Danio With Swollen Red Eye

[Kwiddows]

Hi,
6 months ago one of my zebra danios lost an eye - there was no indication of infection or other physical damage, it just wasn't there anymore. The danio was absolutely fine with 1 eye until this morning when the remaining eye was hugely swollen, popping out of his head, and bright bright red. I don;t know fi this was the right thing to do, but I was so worried about him ending up blind that I euthanased him this morning with ice water.

I'm worried though that it might be something in the water that could affect the other fish or something I may have done to injure him when I cleaned the tank yesterday (he was fine before I cleaned the tank, and seemed fine after I finished it was only this morning I noticed the eye).

My question is - should I treat the tank for something now to stop the other fish getting the same problem?
Thank you.

Tank size: 4feet long, 18 inches high, 1 foot deep
pH:8
ammonia:0
nitrite:0
nitrate:40ppm
kH:240 - the water is always this hard
gH:180 - the water is always this hard
tank temp:26 degrees C (a little high for danios I know - but they have been quite happy in there for over a year)

Fish Symptoms (include full description including lesion, color, location, fish behavior):

The now dead fish had already lost one eye (but been fine for 6 months) and this morning the other eye was really massively swollen and bright bright red. He was also hiding a lot and wasn't swimming with the others as normal.

Volume and Frequency of water changes:

The tank at the moment is being looked after by parents while I move house so water changes are not regular they are only when I can back here to do it. Last change was 3 weeks ago about 50% and then yesterday 50%. But the tank is way under capacity for fish stocking and has 2 filters running, so although its not ideal its not as bad as it sounds.

Chemical Additives or Media in your tank:
Easy life and aqualibrium at minimum dose levels also plant food - plantamin

Tank inhabitants:
1 yoyo loach
4 zebra danios (there were 5)
5 jullii cories
4 neon tetras (4 died when I moved the tank to my parents house and I don't want to add more fish until I move it back again)
8 black phantom tetras
A couple of amazon swords which are not doing very well since I moved the tank to my parents place
Several other plants which I cant identify which are all growing very well

Recent additions to your tank (living or decoration):
4 phantom tetras added about 3 months ago - nothing since then

Exposure to chemicals:
None I am aware of

Digital photo (include if possible):
Can't get a file small enough to upload.

 

[fluttermoth]

If all the other fish are fine, I'd suspect injury.

Could be your yoyo loach; they can be quite aggressive when kept singly, so you might want to keep a close eye on that.

If you want to post a pic, you need to upload it to a hosting site, like Photobucket or Flickr, and then paste the IMG code into your post

 

[Kwiddows]

If all the other fish are fine, I'd suspect injury.

Could be your yoyo loach; they can be quite aggressive when kept singly, so you might want to keep a close eye on that.

If you want to post a pic, you need to upload it to a hosting site, like Photobucket or Flickr, and then paste the IMG code into your post

Thank you.

The yoyo has never been aggressive as far as I know. I wondered about that too as some advise to keep them singly and some advise larger groups of at least 5 - but he seems to have never caused a problem (I thought he was killing tank mates a while back but it turned out to be a lone rosy barb which got aggressive when the other died - I took back to the shop when I realised it was him and since then I've had no problems)

Thanks for the photo advice too - I've added links as the images wouldn't display in the post preview - They are not very clear I'm afraid:

This is the top view
http/www.flickr.com/photos/61751043@N06/7740954578/in/photostream/

This is the view from the bottom
http/www.flickr.com/photos/61751043@N06/7740955504/

I'm really hoping I didn't do it to him while I was cleaning the tank - because all the danios are very curious when I do anything and tend to follow me around the tank while I clean the filters etc. But then again - I suppose a one off injury is better news than an infection that might spread to the others.

Do the pictures shed any light on it at all?

 

[fluttermoth]

Hmm, the pics don't really help (me anyway). I'm not sure what else to suggest; just my normal, palliative advice I suppose; keep the water in tip top condition, watch everything in the tank very closely and keep your fingers crossed.

Not very helpful, I know. Hopefully it is just a one off death; we all get them sometimes.

 

[Kwiddows]

Thank you Fluttermoth.

I will just watch them (or get my parents to watch them) for a few days and try to come back next week to check and do another water change. I'm moving house next weekend and after that the tank will come to my new place so I will have them all back and it will be much easier to look after them. Hopefully they will move OK - I lost a few when I moved them to my parents