Bristle nose catfish breathing quick

[snickers1415]

My plecos look like they have a lack of oxygen and are at the top of the tank. All of my other fish seem like they are doing fine and behaving normally. One already died today and I cannot get any PH testing strips because it is night time. I am not sure of the levels of the water in my tank. I have already done a water change and have added some cycling liquid. I only had them for a week and I`ve checked the water temperature. Please help!

 

[Byron]

The best thing to do in this sort of situation is a major water change, and a second later today or tomorrow. Without tests there is no way to know what may be behind rapid respiration, but I have once or twice observed this and did nothing more than a major water change and the issue resolved. The second observation is that the bristlenose were not healthy, which could explain why only they are having trouble. Having said that, something toxic in the water might affect new fish but not be evident with the fish that have been in the tank longer. I've had this too, when a toxin leeched out from a piece of wood over time.