Mouldy Looking/cotton Wool On Rainbow Fish

[alexdallimore]

I noticed one of my rainbow fish separated itself from the other 5 and started swimming in the filter current near the surface. Today I noticed that the others didn't like it anymore and on closer inpection it has a coating of white which looks like a mould/cotton wool down both sides. My levels are Amonia and Nitrite 0 and Nitrate 10-20. The fish came with 5 others from the shop 10 days ago and the other rainbows seem fine with no odd behaviour. I have issolated it about 20 mins ago but don't know what it is, how to treat, and what to do with my water. Help please. The fish will get taken back tomorrow purely because it's new. Just don't want my whole tank to die.

The tank is a 4 ft tank with

6 rainbows (included that one)
2 tiger barbs
3 rosy barbs
albino shark
clown loach
3 chinese algea eaters
5 fake siamese algea eaters

Not my choice of fish as tank bought second hand a month ago. Still sorting them out

No other fish are acting weird.

I do regular water changes. 10% each week and use stress coat and stress zyme when I do


Any idea's

 

[WILDER]

How many gallons is the tank.
Sounds like saddle back columnaris if you have fluffy bits on the side, does it also run along the back of the fish.
http/article.discusnews.com/cat-02/columnaries.shtml

 

[alexdallimore]

Its a 275ltr tank although I recon only about 220ltr water as rena volume is based on external tank size. The coating of what looks like fluff/velvet/cotton wool seems to be pretty much all over.

 

[WILDER]

Velvet looks like a dusting of talc, or a yellow to golden varnish on a fish.
Sounds like columnaris to me if its fluffy.

This is what columnaris looks like.
http/www.2cah.com/pandora/columnaris_noodles.jpg