Perfect Water, Dead Fish

[mhancock]

I have found several dead fish in my tank today, all of them had fins missing. Dead fish: 1 male guppy, 3 cardinal tetras, and my male betta.

Tank has been fine and peaceful, only recent changes have been adding the guppies a week ago, and yesterday I had a flood in the house which meant they did not get fed at their normal time.

Stats:
55l tank
pH 7-7.5
Ammonia 0
Nitrites 0
Nitrates trace
(liquid test kit)

Stock:
5 panda corys
1 male swordtail
1 small plec
7 male guppies
9 Cardinal Tetras

The stocking is heavy (25-30 inches of fish in 15 gallons), however the tank is very well planted, they are all small fish, and I do 80% weekly water change.

Could it be that the Betta had a big fight with lots of fish and they all lost? The tank has been incredibly peaceful thus far. Maybe adding the guppies just made it too crowded, although I thought I was OK with stock, albeit full.

Edit: the betta and guppy both had tail/fins missing, of course this could have happened after they died......

 

[KISSfn]

Sounds like overcrowding and stress brought on a brawl.

 

[mhancock]

Sounds like overcrowding and stress brought on a brawl.

Sadly, whilst I was hoping for another explanation, that is the only likely answer. Some lessons you learn the hard way.....

 

[KISSfn]

I've learned my share and am still learning...