Sudden Death - Waspfish

[iliveinazoo]

Ammonia = 0ppm
Nitrite = 0ppm
Nitrate = 10ppm
PH = 7.5-8.
SG = 1.003 - 1.006 (normally around 1.005)

100litres/26US gallons
Tankmates:
2x Figure 8 puffers
4x Bumblebee Gobies
1x Halfbeak

The waspfish has always been fairly active and up until yesterday when i found him floating at the top breathing very heavily there has been no sign of injury or disease or change in behaviour.
I could not really tell but part of his right hand side appeared to be white, the girlfriend and I could not agree if it was a type of fungus causing the whiteness or because he was missing scales. The only aggressive fish that we've got is the halfbeak but he stays at the top of the tank and they rarely come into contact.

I'm wondering if the salinity is too low and he picked up an infection and couldn't fight it off but I would have thought that we would have noticed something sooner?
We couldn't get RO water from the LFS for a few days so we changed the water 7 days ago with rainwater from a water butt in the garden and I'm wondering whether that water had deadly bacteria in it but again I would have thought that we would have noticed something sooner?
He got attacked that day and even though there weren't any serious wounds he still succumbed to the injury?

 

[WILDER]

The white on the fish did it look fluffy like cotton wool, or just bleached out bemeath the skin. any whiteness around the scales.
Any signs of flicking and rubbing.

 

[iliveinazoo]

The white on the fish did it look fluffy like cotton wool, or just bleached out bemeath the skin. any whiteness around the scales.
Any signs of flicking and rubbing.

No signs of flicking or rubbing. The girlfriend said that it looked fluffy but I thought that it looked more bleached out beneath the skin. It started midway down the body and continued for about 1.5cm and was irregular in shape which made me think that some scales were missing.

 

[WILDER]

If no flicking and rubbing dosn't sound like a parasite involved.
Columnaris can cause the skin and scales to peel away.
I would just do some water changes for a few days on your tank.
http/www.flippersandfins.net/flexibacter.htm

 

[iliveinazoo]

If no flicking and rubbing dosn't sound like a parasite involved.
Columnaris can cause the skin and scales to peel away.
I would just do some water changes for a few days on your tank.
[URL="http/www.flippersandfins.net/flexibacter.htm"]http/www.flippersandfins.net/flexibacter.htm[/URL]

That's a possibility as the suddeness of it sounds about right - maybe he got picked on a lot (so stress) and we didn't see it but it didn't look half as bad as that one in the picture but I'm convined that a number of scales were missing.

And it's very annoying because that tank is the one that we take care of more than any other and even the thought of water quality problems is very strange indeed (but anythings possible). I would have thought that the puffers would have been the first ones to go if it was water quality issues.

Thanks for the help and thoughts.

 

[WILDER]

Stress weakens there immune system, ahd thins there slime coat, so stress can cause columnaris.