threadfin rainbow, Are they Sensitive to Co2 Injection?

[DigDug]

Are Threadfin Rainbows more sensitive to co2 compared to other fish? 

I bought 4, and they seem to be struggling at the top of the tank compared to the Neon Tetra/Shrimp/Sparkling Gourami

 

[laritheloud]

That sounds like it might be an acclimation issue. When did you add them to the tank? Did you add them while CO2 was off and the lights were off? How did you acclimate them?

Did you quarantine your threadfins?

I don't want to be alarmist, but I did have a few pseudomugil rainbows that did this upon adding them to my tank, and it turned out that they were weak fish and ended up getting very sick a couple months down the road. If you did not quarantine your fish, keep an eye on them; if you can quarantine them, I'd move them to a separate tank without CO2 and observe.

[DigDug]

I added them last night, and did it the normal way i do for most of my fish.

They were fine, until the co2 kicked on this morning, although they seem like they are doing better now?  Im thinking about taking them out though, and putting them in another Tank.

This is a new tank, that is cycled, but don't really have many fish in there right now, so kinda treating it as a QT tank 

[laritheloud]

I'd keep an eye on them. Sometimes rainbows can be less robust, depending on source and breeding, especially the smaller species. Good luck!