I Give Up - Total Carnage!

[Gruntle]

Hi all,
 
Last Saturday (27 September) I purchased a dozen Neon Tetras to fulfil my 25 year ambition to own some.  They did fine in the tank and everyone was getting along.
 
On Monday 29th (late afternoon) we made a snap decision to go on holidays for a couple of days.
 
I came home to absolute disaster.
 
Original tank occupants (as at 27 Sept):
2x BN Pleco
5x Head and Taillight Tetra
3x Crimson Spotted Rainbowfish
12x Cherry Barb
12x Neon Tetra
 
Tank occupants as at 3 October (mid afternoon):
1x BN Pleco
5x Head and Taillight Tetra
3x Crimson Rainbow
7x Cherry Barb
5x Neon Tetra
 
Since then I've been cleaning carcasses from the water, changing water, and panicking. As of this morning the neons are down to two (with one very pale), 3 cherry barbs (all of whom seem to be pointing head-down and listless), and nothing I have done seems to have slowed the death rate. I lost two cherries while making a cup of coffee!
 
Ammonia is zero, Nitrite is zero, Nitrate was a bare 20-30ppm on my return (and should now be much lower but I haven't had the heart to check). PH was 7.4. The Rainbows are all now showing lesions (I have a suggestion from a Native enthusiast who believes it may be fish TB), have gone very thin and I don't expect them to last. The only things that seem to be thriving are the mystery snails and the H&T's (and the remaining bristlenose).
 
I fed them before we left. I have left them foodless in the past (barring the neons) for 4 days without issue.  My cherry barbs were breeding in the tank up until recently.
 
I can only think that the neons were diseased and have passed on their infection to everyone bar the H&T's. If this is likely the case there will be a very angry phone call to the LFS (which has an excellent reputation).
 
I'm at the point of letting the remaining few succumb, dosing the tank with chlorine and starting afresh with a whole new fishless cycle. I'm done with it.

 

[sbenbow]

OMG - I am so sorry for you.
 
Definately give the LFS a call - it does sound like the neon's are the culprits as they are the only new additions to the tank and all the other readings / tank params sound fine.
 
Fingers crossed for the survivors.

 

[star4]

To 100% confirm TB a dead fish would need to be sent off to a laboratory, if your LFS is good they will know where to send it. However your death rates seem very fast for TB, this usually takes much longer to show, other symptoms appear first, yes leisions are part of it. Do any of the fish have bent spines? looking at them from above they would have an S shape to the body.

 

[Byron]

I would also check with the store to see if they have lost neons, which would at least pinpoint the source absolutely.  QT all new fish is really advisable these days, as I have learned by a couple of very tragic and similar circumstances.
 
Byron.

 

[Gruntle]

No losses for 24 hours, cherries are swimming almost normally again (those I have left, anyway). I'll call the LFS to see if they've had issues with their neons.

 

[sbenbow]

I'm really glad things are getting back to normal (or as normal as they can be with depleted stock).  Fingers crossed that that is the last of it.

 

[DrRob]

Could possibly have been a mini spike after the introduction, although I'd be somewhat surprised that the biofilter couldn't cope with the addition of 12 small fish given the existing stocking. You didn't lose power whilst you were away did you? A mixture of an increased bioload with a filter going down for any length of time might account for it if the LFS have had no trouble.

 

[Gruntle]

I guess a loss of power isn't totally out of the question, we had builders onsite (although they just laid some concrete and put some rails around the deck). I don't know, because in my second tank I added 3 male and 3 female Endlers at the same time and they're thriving (one of the boys even rushes over to the glass in the mornings to greet me/get some food).
 
I did some painting, so perhaps there's an issue with fumes (but the tank has a fairly complete lid apart from the outlets for the filter hoses).
 
It might remain as one of those eternal mysteries. Without being there I can only try and piece it together. I was surprised to see my BN pass on, she wasn't very old (6 months). Maybe she caught something and died, and the others had a nibble (her belly was gone by the time we got home).