9 out of 12 concivcts dead????

[cbheternal]

last night one of my female chiclids was doing the death swim. checked my levels. nitrate was 5.0 ppm everything else was fine. changed some water. gravel vacume. nutting out of the ordinary. the crazy swimmer died, before bed. woke up this morning. and 9 out of 12 fish were dead. these fish. were strong. no tank issues. please help. baby did this happen.

 

[HN1]

How long have you had them? What size tank?

 

[cbheternal]

20 gallon. Aquaclear 30 had the fish for 6 months. they were a rescue. when i got them. the water was so bad. I thought there was only 4 fish. drained the water found 12. they were in a 8 g

 

[HN1]

My guess is that they are maturing and the relatively cramped conditions are now leading to stress and aggression.

 

[cbheternal]

this is messed up. there were no signs of any issues.. no scale problems. no burning of the gills. just the one crazy swimmer. thought swim bladder infection. after the PWC. they were all huddling in the pirate boat. looked almost like they were in mourning. this sucks. so sad.