Don't be too quick to remove humic substances (things that "stain" your water brown) from your pond.

[MitchM]

Humic substances have been shown to be beneficial in many ways. Humic substances have anti-fungal, anti-parasitic, antibacterial properties and can protect fish from many environmental stressors such as low O2, PH swings, high ammonia and nitrite levels.
Humic substances can also prevent outbreaks of cyanobacteria and prevent algae growth.

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.317.9931&rep=rep1&type=pdf

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[Meyer Jordan]

After briefly readings this paper, except for certain circumstances it seems that there are more cons than pros in maintaining high humic acid levels in a pond.
The primary and obvious effect it that it will reduce light penetration, retarding algae (periphyton) growth resulting in a lower Dissolved Oxygen level and a lower density and diversity of zooplankton.

 

[MitchM]

I wouldn't recommend high humic levels, but my takeaway is that HC has a stressor effect on fish similar to antibiotics on humans. It allows their bodies to adapt to poor water conditions and helps fight off bacterial infections that come from bacteria such as Aeromonas hydrophila.

Forgot the link
https://www.researchgate.net/figure...activation-of-Aeromonas-hydrophila-ATCC-35654

 

[Meyer Jordan]

I wouldn't recommend high humic levels, but my takeaway is that HC has a stressor effect on fish similar to antibiotics on humans. It allows their bodies to adapt to poor water conditions and helps fight off bacterial infections that come from bacteria such as Aeromonas hydrophila.

Forgot the link
https://www.researchgate.net/figure...activation-of-Aeromonas-hydrophila-ATCC-35654

Possibly, but an already otherwise healthy fish would have this ability anyway considering the ubiquitous nature of Aeromonas and other pathogens

 

[MitchM]

I suspect that most of our pond fish have higher levels of stress than we care to admit.

 

[Meyer Jordan]

Of that, you can be fairly certain.

 

[Lisak1]

I suspect that most of our pond fish have higher levels of stress than we care to admit.

That makes me sad... although "stress" in a fish is not the same as human stress, but still. Are there factors that can reduce that stress, or are we talking natural stressors like harsh weather conditions?

 

[MitchM]

That makes me sad... although "stress" in a fish is not the same as human stress, but still. Are there factors that can reduce that stress, or are we talking natural stressors like harsh weather conditions?

I'm talking about conditions that we as pond owners overlook when the focus of our pond is appearance instead of the ecosystem; water condition, hiding places, overcrowding, fish nutrition, lack of biodiversity.
Those kind of things.

Humic acids or humic compounds (HC) are present in all water and can play an important role in the health of a fish.

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[Lisak1]

Gotcha. So things we could control with some thought and care. It may sound silly, but I really do want my fish to be "happy", whatever that means in the fish world. Less stress = healthier fish, so it's a good goal to have!

 

[MitchM]

Gotcha. So things we could control with some thought and care. It may sound silly, but I really do want my fish to be "happy", whatever that means in the fish world. Less stress = healthier fish, so it's a good goal to have!

I think so too.
Our ponds are closed systems so they'll never be perfect, but I think we should keep those considerations in mind.

 

[MitchM]

Humbolt University in Berlin has a group whose focus is freshwater and stress ecology.
https://www2.hu-berlin.de/biologie/aquaoeko/index.php5?goto=research