Cloudy eye on rainbow and swordtail Please help.

[dnaelting]

Last night I was doing my water change on my 70 gallon tank and noticed one of the turquoise rainbows had a cloudy eye that was slightly swollen. Otherwise it acted fine. This morning I found one of the swordtails also had a cloudy eye that is slightly swollen, but it is hiding in the plants. I also found one of the cory cats dead.

There have been no additions to the tank in months.

Water parameters:
Temp 77.5
Ph 8
GH 13
KH 7
Amonia 0
Nitrite 0
Nitrate 10

The tank has been up and running for about a year. It is planted and has 5 rainbows, 3 adult swords, 5 juvi swords, 2 cory cats (after the loss), and 20 guppies.

The only change I can think of is we bought a new can of flake food since the old one got used up. Same type of flake food, so I don't think that would be the issue.

Any ideas?

Thanks.

 

[dnaelting]

Forgot to mention feeding. We feed 3 different flake foods, and once a week they get freeze dried blood worms, and once a week they get a frozen food treat.

 

[dnaelting]

Just in case anyone else ends up in this situation. My water quality tests great, and there have been no additions recently to the tank. This hit accross fish types, both rainbows and swordtails, and was moving fast. I went to:

http://www.nationalfishpharm.com/diseases.html

and found it could be bacterial. I bought some Marycin Two and started treatment. The fish are recovering now.

Now I am left trying to figure out how it got started. I know the swordtail is prego and about to deliver, so she may have been comprimised. But there is still a question of how the bacterial was introduced. If I find out more I will let you know...

 

[sudz]

Is it possible that its just always been there, but since the fish was pregnant her immune system was weakend? Contact with your rainbow might have spread it?

Just a guess. *shrugs*

Good luck with recovery! sounds like you know what you're doing.

 

[dnaelting]

possible, but cant know for sure. With how fast it spread, I would have to say there must have been something bringing it into the tank. I am going to check everything I can. I can only figure something in the food...