Balas not acting right.

fender

I have 5 juvenile Bala Sharks. They've been behaving normally, adapting well and eating for the past two weeks. My tank is 80 gal well aereated and planted. Chems test out good. Today when I can home I found them schooling tightly in one corner of the tank and dropping one at a time in a vertical position before returning to the school. Any ideas?

1077

A bit more information would be helpful.
How long has the tank been running with fish? What are exact readings for pH, ammonia,nitrites,and nitrAtes? CO2 injection?
Would submit that Bala sharks do best with moderate to strong current and often will posisition themselves at point where water returns from the filter into the aquarium if current is lacking.
Also appreciate Oxygen rich water which might prove to be problematic providing in planted tank without driving off CO2 that plants need?

fender

Thanks for replying. All testing is well within range except for GH which I will correct with A deionized water exchange. The tank has been in continual operation for ten years. It was a cichild tank previously. When the community dwindled, some fish living for 7 years, I rehabilitated and left it dormant for 1 month before changing it to an asian tank. All was well then they started acting odd. The temp is 82 -84F so I'm dropping it to 78 - 80F also. Between that and the GH adjustment, I'm hoping it makes a difference. BTW, Im not needing to supplement the CO2 at this time. The plants seem to be doing well with Fertilization. Tests don't show out of balance CO2. I'll post results. Thanks again.