Oxygen and fish growth...it's true!

[FINWIN]

The topic of oxygen and fish growth has long fascinated me. It came up in another thread so I decided to do some looking into it. Something having to do with tissue efficiency and all that. I've always been big on water movement as a calming method for boisterous fish and keeping debris controllable. But I never thought about the growth factor. Over time I noticed most of my fish would grow to maximum known size and then some. At first I thought it was coincidence. Not.

female acara 6 inches
female rainbow 6 inches
male hrps that look like baby chancos 5-6 inches
all parrots near or over 8 inches
rapid hrp fry growth rate even at high density
synos nearly doubling in size over a year and a half
not certain about growth influence on Oscar. currently 15 inches at 4 years
uncertain effect on my previous severums
female hrp over 4 inches
female chocolate at 10 1/2 inches still growing at time of demise

here is some info I found. One is a long paper for those of you science based.

graphic



articles

Dissolved Oxygen In Water: PPM For Fish | Atlas Scientific

Fish require dissolved oxygen levels between 5-6 ppm (parts per million) to grow and thrive. Low dissolved oxygen levels (>3 ppm) become stressful for most aquatic organisms, and extremely low levels…

atlas-scientific.com

https://www.grocentre.is/static/gro/publication/58/document/yovita07prf.pdf

(science paper)

The Importance of Dissolved Oxygen Levels for Fish Growth | Aquasend

Fish breathe oxygen just as we do, so dissolved oxygen (DO) is a critical environmental indicator in aquaculture. Depleted DO is the leading cause of fish kills, and fish farmers […]

www.aquasend.com

 

[dmyersWv]

Great info. I've noticed the increased growth in my heavy flow tanks also. When I added wave makers and airstones to my gry out tanks.

 

[TwoHedWlf]

The atlas scientific one says they require 5-6. But greater than 3ppm can become stressful.
You can't have both!

 

[Dutchaj]

TwoHedWlf That says less than 3ppm is stressful

 

[TwoHedWlf]

TwoHedWlf That says less than 3ppm is stressful

It may have intended that, But that's not what "Greater than 3ppm" means. "<" is less than. ">" is greater than.

 

[neutrino]

I suspect a typo, considering it says: "Low dissolved oxygen levels (>3 ppm)."

I'd just note that the upper end is not limitless, gas oversaturation can cause serious issues (it's not just oxygen, more often it's nitrogen-- think of the bends) and it's more of an issue in warm and shallow water-- like most of our tanks. It's a known issue for fish farms, etc. and occasionally in the hobby. The commonly recognized causes are pump intake issues, sump issues, and cool, pressurized tap water, but if you research it spillways in rivers are a known cause with an obvious aquarium corollary. Results speak for themselves, not questioning good results, and it's a complicated subject-- just something to be aware of, it's possible to overdo it. Oddly enough, besides such symptoms as bubbles in the eye or skin, fast breathing can be a symptom.

 

[duanes]

One other aspect of this, that is just recently being studied, and published, is how elevated nitrate, hinders a fishes ability to access that oxygen, by muscling out dissolved oxygen in the water column.
And beyond stunting growth, can create enough stress to cause chronic maladies like HIITH.
When compared to natural nitrate levels, what is generally accepted by aquarists as OK, is quite different.
I have collected in at least 6 different rivers over the last 6 months, and tested nitrate levels and pH in each one.
Below are typical the results. The left tubes are e nitrates, the right tubes are pH



I often A/B each liquid test, with a strip, just to compare accuracy of either test.

 

[duanes]

A lot of tolerance, or intolerance to varied DO levels depends on species, and what natural habitat they have evolved to exist in.
When I worked as a chemist at a lab that tested raw Lake Michigan water daily, the average DO content was in the 8 to 10 ppm range, and coincided with water temp, an average of 50"F and lower depending on the season. The most common fish species in that lake are trout, and salmon, requiring those high DO levels.

Here in Panama where I now collect fish, the average water temp is around 80'F, a temp which may hold only 5ppm, when fully saturated.


You can see that flow, riffles and rapids are important factors in saturating DO and promoting the gas exchange they need, along with the non-detectable nitrate.
The thing is, the type species found in highly oxygenated environments like the photos above, where tetras, plecos and cichlids live, are quite different, and contain totally different species than low flow environments like the ones below.

In these low flow environs, mostly smaller species adapted to live near the surface, a zones where due to stagnant conditions, atmospheric oxygen is allowed to penetrate only a few inches into the water column.
Here in Panama this zone usually only contains live bearers, and killifish.

But not only here, the world over adaptations abound, such as the labyrinth organs Anabantids have evolved to bypass the low oxygen environs and use atmospheric oxygen.

 

[dmyersWv]

Great photos. I appreciate all the info you provide.

 

[esoxlucius]

It's way more complicated than just oxygen levels. Tank size, feeding regime, quality of food, stocking levels, compatibility of said stock and each hobbyists individual nitrate tolerances all play a part.

Your oxygen levels might be perfect but your fish could still become stunted if all the others issues are neglected.