SA wrote:
I cannot believe I did this but I think I managed to kill an entire
tank of cichlids tonight. I am really bombed out about it.

I have a 45 gallon tank with some juveniles thriving for the past 3
months. Typically I changed the water once a month when I had some
community fish in there and once the cichlids were really small.
Today I decided to test for nitrates and switch to a biweekly water
change. I had changed 25% two weeks ago. The nitrates were kind high
so I decided to a more aggressive water change around 40% of the
water, I used a python like I always do and filled the tank up with
water close to temp as the tank. The thermometer did not register a
temp change and the heater stayed up after it was full for maybe 3min
I used a water treatment in the tank. immediately after this all my
fish went to shock, sitting at the bottom of the tank still gasping
for air. Couldn't understand what went wrong initially I thought they
were just frightened because of the substrate vacuum etc.

Two hours later still gasping and one already dead... I'm afraid they
will be more!

I am so mad right now.

Any comments as to what might have gone wrong are very much
appreciated.

And just yesterday I was bragging about their colors and behavior to
my wife, I screwed my self so bad.

TIA

Steve

Use Amquel next time. It's the best friend to a Python system. Works quick,
and eliminates Nitrates and Ammonia.. nitrites too!!