Multiple unhealthy Rainbow Fish

[Built2Prfctn]

I have a tank of about 15 Rainbows. Im noticing they are turning white and losing color and even bruising.

My water specs are perfect. No nitrates/nitrites/ammonia.

Only thing I can think of is the C02. Can this be causing it? Maybe over dosing. Fish seem to be acting normal.

HELP!

 

[Byron]

I stay out of disease threads as it is a very complicated topic and my experience is fortunately very minimal. But I can suggest a couple things for you to provide that will help others.

Can you provide the GH and pH of your water and the temperature. And the species of rainbowfish, along with any other fish in the tank. Tank size (volume and dimensions).

By CO2 you mean diffused CO2 for plants presumably. This does affect fish, but I wouldn't think that the issue here, though it may not help.

 

[Colin_T]

Pictures please.

What have you done to the tank in the last 2 weeks?
Have you added anything new to the tank in the last 2 weeks?

How often do you do water changes and how much water do you normally change?
When did you last do a water change?
Did you dechlorinate the water before adding it to the tank?

The following link has information about what to do if you fish get sick. It's long and boring but worth knowing. I recommend printing it out and reading it in bed to help fall asleep.
http://www.fishforums.net/threads/what-to-do-if-your-fish-gets-sick.450268/

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Do a 75% water change and gravel clean the substrate every day for a week.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

Clean the filter if it hasn't been done in the last 2 weeks.

Turn off the CO2 and increase aeration/ surface turbulence until the problem is resolved.