Did this kill my arowana?

[Bderick67]

Ya, I would just be curious to see how quickly you tank proccessed the ammonia and nitrite. Also I would try to figure out if the ray is the problem. If you are feeding it a large amount of food and it then takes a large dump later on this could be the reason for spikes. I know other have suggested that is could be leftover food but I would doubt that could or would be the problem.

 

[6 bar]

I'm not thinking it is left over food either so much as fish waste. Between the stingray, the 4 loaches and the flagtail most foods get consumed.