Canary in a coal mine

[Gershom]

I have a pearl gourami which is deformed, with an upturned mouth/nose. He seems to be a healthy, aggressive fish, and was picking on my other male. So I put him in with some South American cichlids. It does fine in there.

This morning when I got up, all of the fish in that tank were at the surface. Clearly low on 02. I turned off the under gravel powerheads and added air stones, which seemed to solve the problem temporarily at least. But I watched the gourami, and it was still returning to the surface to breathe at frequent intervals.

It occurs to me that they can be used as a canary, to monitor the water. They can breathe air, and also have gills, but their gills probably are less effective than other fishes gills. If the gourami surfaces frequently, the water may be low in O2!

 

[skjl47]

If the gourami surfaces frequently, the water may be low in O2!

Hello; Maybe. They and the others of the kind (bettas for example) would go the surface often enough in my experience. An interesting thought tho.

 

[jjohnwm]

It would seem reasonable that an air-breather would surface more often in oxygen-depleted water than it would in water that is well-aerated. But it also seems that you would need to know the "typical" air-gulping routine to be able to compare it to the current one; sounds like it would require a lot of careful monitoring to determine both of these things.

I'd think that in a mixed community-type tank, the behaviour of the other non-air-breathing species would be an easier thing to observe for potential problems? I dunno, just thinking out loud.

 

[esoxlucius]

If labyrinth fish only breathed air at the surface when there was low oxygen, and absolutely no other time, then you might be onto something.

But labyrinth fish breathe air from the surface all the time, it's just their nature in my experience.

My giant gourami was always "topping" his labyrinth system up, even though surface agitation/oxygen levels were fine.

 

[Gershom]

All reasonable observations, and I agree. I was trying to say “more often than usual “.
But I guess the norm would vary depending on several things, including water temperature, gourami size and species, activity, etc…. So the numbers will only be applicable to a given situation, and therefore likely not clinically useful—sorry.

 

[skjl47]

So the numbers will only be applicable to a given situation, and therefore likely not clinically useful—sorry.

Hello; No reason to be sorry. In fact after some thought, it does appear some fish react to low oxygen water differently than others. I have seen such on the occasions of low oxygen water in my tanks. I did in the past overstock tanks so had incidents of finding fish gulping at the surface. Unfortunately I did not take particular note of which fish seemed troubled and which did not.
Another bit of fishing lore may apply. When the water temperatures rise during the hotter parts of the warm season I have heard the bigger fish go to deeper water. The shallow water becomes low O2. So, you need to fish a bit deeper.

Your idea is not so far fetched.

 

[Gershom]

When the water temperatures rise during the hotter parts of the warm season I have heard the bigger fish go to deeper water. The shallow water becomes low O2. So, you need to fish a bit deeper.

Your idea is not so far fetched.
[/QUOTE]
Interesting—I hadn’t thought about the fishing context, but certainly warmer water holds less O2. Considering how drastically less O2 there is in water vs air, many fish are probably more accustomed to being a little “short of water”.

And the adaptation (and tolerance) to that state is varied between species, probably much more than just air-gulpers vs non-.

 

[skjl47]

Hello; Back in my younger days I could dive into the waters of Norris Lake in TN. I could hit the thermocline layer and go from warm water to deeper cool water.