[WaterLife]

Just wanted to hear experiences on what fish you find to tolerate high levels of co2 (30 ppm) exponentially well (very little to no signs of distress).

Also what fish did you find particularly sensitive to higher levels of co2?

To keep the list short, just mention fish that do remarkably well or very poorly with high co2 levels, and just skip all the fish inbetween (we'll just consider those to have a fairly good tolerance, not their happiest at high co2, but still doing pretty well).

 

[Grah the great]

I don't use CO2, but I'm pretty sure anything that breathes air will not have an issue in such conditions as long as the PH doesn't wildly swing around with the CO2 concentration.

 

[Nordic]

I would venture the bottom dwellers.

 

[theatermusic87]

I would guess the labyrinth fish that can breathe at the surface

 

[jaliberti]

Grah the great and theatermusic87 have got it right, anything that breathes air, Labyrinth fish.

Don't know much about wildly swinging pH with the CO2 but Gambusia, which are not Labyrinths, can live - even thrive - in an oxygen depleted fluctuating chemistry. They're difficult to kill.

 

[Nordic]

there is a difference between low O2 and high concentrations of CO2.
Even a fish that tolerates high CO2, might not like being taken from a low CO2 environment into a high one without some time to adjust to a gradually increasing level.

 

[WaterLife]

Reason I ask is because some people have noticed some fish species are more or less tolerant of elevated co2 levels. Some would balance things out, by adjusting co2 levels according to how the fish tolerate it (whether that be less than 30 ppm), but the point is they were noticing that some fish tolerate high co2 levels better or worse than others (signs of distress to little or none). So I was just wondering what fish were noted to be sensitive to high co2 levels (or whether it's the pH fluctuation) and what fish species seemed unphased by high levels of co2.

Just to clarify, I mean the regular 30 ppm co2 levels, 1.0 pH drop throughout the day, and just assume oxygen levels are sufficient (not low o2, enough o2 or high levels of o2 from plants pearling). And yes I would slowly acclimate/introduce co2 changes to the fish.

Fish that can breathe air make sense that they could survive higher co2 concentrations. But what else? Referring more so to the typical community fish (planted tropical tank after all).

 

[burr740]

In my tanks Otos are by far the first to show signs of distress. Other inhabitants include Tetras, SAE, Cories, and Fancy Guppies. The guppies seem to have the highest tolerance.

I realize this isnt much info, just what Ive observed in mine.

 

[mistergreen]

Stream fish where they're used to high O2, low CO2 usually do poorly in high CO2.
These are loaches.

 

[Brian727]

Personally I couldn't kill my long fin zebra danios with too much co2. Same with the mollies. My Panda Garras and Cory cats were fine as well.