Do Fish Also Need Carbon Dioxide As Much As We Do?

yerrag

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When we aerate an aquarium or a fishpond, we are increasing the surface area of water that contacts atmospheric air, so that oxygen gets dissolved in water for the fish to breathe in using their gills. Along with oxygen, other gases such as nitrogen and carbon dioxide gets dissolved as well.

When I search the web, I read that fish need oxygen and I don't read about the fish needing some carbon dioxide. In fact, what I read about is that the higher the dissolved carbon dioxide level is, the more difficult it is for the fish to release carbon dioxide from its blood to the gills.

But I want to know if there is a certain level of dissolved CO2 in water that would be optimal for fish health. What I seem to be getting is the idea that only dissolved oxygen is needed, and that any amount of dissolved carbon dioxide is not needed.

Does this mean then that I could simply replace the aerator in the pond with an oxygen tank, and be able to provide superior oxygenation to my fish? After all, oxygen is good and carbon dioxide is bad, right? Let's just assume that there are no plants in the aquarium or pond, so that we don't get to talk about the benefit of carbon dioxide to plants, as this will muddy things up.

I'm asking this because steeped already as we are in Peat, we know that carbon dioxide is needed for us to have adequate tissue oxygenation. And we know how the mainstream medical narrative differs from this view. I wonder also if such twisted thinking also applies in other areas of life that is not human, fish particularly.

I am a koi hobbyist, and I take my koi to the local koi shows in Manila once a year. There are two competing koi shows. One using aerators to provide oxygenation, while the other uses pure oxygen from oxygen tanks. When I say aerators, it is just using air to constantly keep the water in the vat filled with adequate dissolved oxygen for the fish.

Which of the two methods is better? Better in terms of not creating unnecessary stress for the koi during the duration of the show, which lasts for about 2 days? Note that koi are already going to be stressed these 2 days. They are fasting, and the vat water would be high in ammonia from their waste excretion. Ammonia is toxic, so water changes are necessary, but the ammonia toxicity levels can only be minimized, but not eliminated during the duration of the koi show.
 
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Spokey

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I'm not sure the mainstream science is really in opposition to this view, it's just that mainstream medical practice has lost sight of the science and history of CO2 and sometimes hyperventilate patients to death. I suspect the physiology is pretty similar for most animals. Excess oxygen seems like it might be another stressor.
 
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yerrag

yerrag

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I'm not sure the mainstream science is really in opposition to this view, it's just that mainstream medical practice has lost sight of the science and history of CO2 and sometimes hyperventilate patients to death. I suspect the physiology is pretty similar for most animals. Excess oxygen seems like it might be another stressor.
I'm right there with you Spokey. I was hoping someone though could point me to a study or a book so I could make a good case with the show organizer to go with aerators instead of oxygen tanks.
 

Spokey

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I don't know of any in fish, I guess there might be somewhere, but then I also wonder if there are any supporting the use of oxygen tanks to justify their use in the first place...
 
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yerrag

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I don't know of any in fish, I guess there might be somewhere, but then I also wonder if there are any supporting the use of oxygen tanks to justify their use in the first place...
I'm just going to have to tell the koi show organizer that uses oxygen tanks that I can't join his koi show anymore. I'll give him my reason, but he'll just laugh it off and then say I'm full of pooper.
 

Adrian

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co2 is used for aquariums with fish and plants
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yerrag

yerrag

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Adrian

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Thanks Adrian. I've wondered about this. Is the reason to inject CO2 because of the plants mainly? If there were no plants, would CO2 still be necessary? I mean, is the carbon dioxide content in air be enough?

I think it is mainly used for the benefit of plants, I experimented with an aquarium with small fish and only achieved overpopulation of microscopic algae.
 

Adrian

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It would be interesting to see if there are long-term changes but I do not continue with the experience.
 

tara

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I have no special experience or knowledge of fish.

I'd be surprised if the fish, any more than humans, need or benefit from having CO2 supplied under normal conditions. I'd expect them to be producing CO2 themselves out of the oxygen, just like us mammals do, for much higher than normal atmospheric or aquatic concentrations in the places they need it.

Like Spokey, I'd be considering/looking into whether or not excess oxygen might be a possible unnecessary stressor (I don't know whether or not it would be in the set up proposed).
 
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yerrag

yerrag

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I think it is mainly used for the benefit of plants, I experimented with an aquarium with small fish and only achieved overpopulation of microscopic algae.
Probably so. Injecting CO2 into water will mainly benefit plants. I was thinking that for fish, the CO2 fraction in air will probably be sufficient to support tissue oxygenation. My fear is that the use of pure O2 for oxygenation, in place of aeration, of water, robs the water column of the little amount of dissolved CO2 that would help koi oxygenate their issues. In a pond, the algae provides some CO2 as well. But in a koi show vat, it seems to me using oxygenation rather than aeration offers little chance of CO2 being available to aid with releasing oxygen from the fish's blood into the tissues.

I'd be surprised if the fish, any more than humans, need or benefit from having CO2 supplied under normal conditions. I'd expect them to be producing CO2 themselves out of the oxygen, just like us mammals do, for much higher than normal atmospheric or aquatic concentrations in the places they need it.
I wonder if fish rely on glucose for metabolism as much as we do. It seems they rely more on fat oxidation, as in the water, there isn't enough sources of sugar. CO2 may be more of an essential substance for them, as it's possible they produce little or none of it, and they would rely more on an external source for it, as in dissolved CO2 in the water column. Then again, if they produce their own vitamin C, as most animals do, they would definitely have to rely on glucose as a precursor for vitamin C.

Not that fat oxidation is incapable of producing CO2 as a by-product. So you may be right on this as well.
 

tara

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I wonder if fish rely on glucose for metabolism as much as we do. It seems they rely more on fat oxidation, as in the water, there isn't enough sources of sugar. CO2 may be more of an essential substance for them, as it's possible they produce little or none of it, and they would rely more on an external source for it, as in dissolved CO2 in the water column. Then again, if they produce their own vitamin C, as most animals do, they would definitely have to rely on glucose as a precursor for vitamin C.
I just looked up and read that koi are omnivorous. In mammals, both glucose and fat oxidation produce CO2, though I think glucose oxidation produces it at a somewhat higher rate per O2. Protein that is to be used as fuel is first converted to glucose. I'd be very surprised if koi are not producing most if not all of the CO2 they need under good conditions.
Even though there may be some downsides for humans running on fat as the primary fuel on very low carb diets, we know there are people who live for years like that. They will be producing quite a bit of CO2, even if it is not always quite up to optimal relative to their ventilation rate.

You know there isn't very much CO2 in air (~0.04%) compared with what we need to have in our systems - if we were relying on that we'd be in much bigger trouble than we are. That's why it's important that we can maintain good cellular production of it.
 

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