Mysterious Death, Neon Tetra

[Mournelithe]

I was hoping that someone here could help me figure out what happened to this Neon Tetra.



The Tank
- 30 gallons, Above and below ground filters
- Aeration via stone + power head.

Stocking
1 yo yo loach
5 zebra Danio's
5 Neon Tetras
+ assorted plants, densley stocked


pH = 7.8
Temperature = 71


Symptoms: This morning all 5 neons were healthy and eating. I noticed no problems from any of them. I did a partial water change (I do a water change of 5 gallons every week to pick up excess food/debries and to prune plants if necessary). In the evening I went to feed one and noticed that one was very listless and apart from the rest. About 30 minutes later he (I think) was having trouble swimming and was in obvious distress. Gills were pumping very fast but the colors were dark. No fins were torn, clouded or otherwise discolored. I am fairly certain it wasn't NTD as the fish did not exhibit the classic symptoms (no abnormal curvature of the spine, no fading in colors or white bloches). The neon settled to the bottom and was on its side when it was taken out and euthanized.

The decline happened very quickly, luckily I don't see any sign of problems from the rest of the Neons, the danios or the loach. Any ideas?

 

[WILDER]

Water stats would be good in ammonia,nitrite,nitrate, and ph.
Sounds like swim bladder, did he swim upside down, bloat up, and couldnt maintain his balance in the water.

 

[Mournelithe]

Water stats would be good in ammonia,nitrite,nitrate, and ph.
Sounds like swim bladder, did he swim upside down, bloat up, and couldnt maintain his balance in the water.

The neon was a bit bloated.

pH is 8.
Ammonia is 0
Not sure about Nitrite or Nitrate as I don't have a test kit for that I will look into it though.

Just as a follow up, no other fish either appear sick or have died.

 

[WILDER]

If the fish was bloated and swimming oddly sounds like swim bladder, hard to cure once it has advanced.
Cook some frozen peas in boiling water for a few minutes, let cool down, pop out of shell, mush between fingers and add to the tank.

 

[vinylman]

The temperature seems a little low.