Need help!!

[Dane.w]

Got a 40 gallon, set up with for for about 5-6 month now with fish, and suddenly all of them are breathing fast and one even tried to jump out of the water
Ammonia 0
Nitrite 0
Nitrate 0-20
I’ve done a 50% water change
Please help I don’t want to lose any

 

[JuiceBox52]

Do another water change

Have you added anything to the tank?
Have you recently done a water change?
Recently added fish or decor?

 

[PheonixKingZ]

Fast breathing usually indicates ammonia poisoning.

Test the water again (for ammonia) and make sure to follow the test instructions exactly.

 

[Dane.w]

nothing new has been added to the tank at all pretty much been the same since day 1, and I did a water change on Saturday which is when I usually do it (each week)

 

[JuiceBox52]

Do a 75% water change. I'm not sure what could he causing it. Doesn't sound like ammonia poisoning to me, probably something else

 

[Dane.w]

I’ve done it twice followed the instructions exactly, set timers but it’s still yellow (0)

 

[Dane.w]

25% to add to the 50% I’ve done or just a whole 75%

 

[JuiceBox52]

Probably a whole 75% the more water removed the better

 

[EllRog]

Be mindful of having anything on your hands that can contaminate the water or any contamination on equipment used during the water change. Is the water airated?

 

[Essjay]

Anything sprayed in the same room? Any painting done in the last few hours? Any children who could have put something in the tank?

 

[PheonixKingZ]

Anything sprayed in the same room? Any painting done in the last few hours? Any children who could have put something in the tank?

This is a possibility. Even Febreze™ could have done something.

 

[utahfish]

also take room temp and tank temp into consideration. Warmer water has less available oxygen in it which could cause fish to gasp at top as well. Can be helped by lowering temp or agitating water to create more oxygen. If oxygen is the issue.
I agree with others could also be ammonia spike or a containment in the water like soap or hand sanitizer or like has been mentioned some kind of aerosol spray, paint fumes.