Aggresive tetras ??

[Dj1ford]

I have 12 neon tetras and have had them for about 3 months in a 240 litre (approx 50 gallons) and they have started attacking each other nipping off fins and mouths. I have saved one which has only half it's mouth left by putting him in with my fry tank a couple have had half there tail fins removed and others are showing damage around mouths and fins, can anyone explain this behaviour as I thought these were peaceful shoaling fish.

 

[mudraker]

When neons attack each other it is usually because there is an illness in the tank, usually caused by poor water conditions.

What are your water parameters/test results?

How often do you perform PWC?

 

[Dj1ford]

Usually done weekly missed last week as I added quite a few new plants, readings today read
20 ppm nitrate
Trace nitrite( not quite zero but not in first colour band of 0.25)
0 ppm ammonia
7 kh carbonate hardness
7.1 ph with co2 injection.

Compared to 2 weeks ago nitrate has dropped from 80 ppm at which point I did 50 % water change and then for 3 days 20% a day to get it down and now looks as though plants are helping to keep that down, did 20% change last Thursday. And this is done on a weekly basis. Will take pics of tank so you can see what's in it.

 

[Dj1ford]

These are pics of tank.

 

[mudraker]

They are probably stressed from the elevated nitrite reading, even if it is low. Keep changing the water until it is firmly 0.

 

[Dj1ford]

Ok thanks will give it another 20% tomorrow and keep testing the water to ensure the nitrite does not elevate. Would have done it tonight but I am short of de- chlorinater.