Effect of Hard water on Soft water fish?

[FishFinatic77]

I was wondering if there are any scientific studies about the effect of hard water on soft water fish? Are there any I can find online? I know that living in the wrong water is bad for fish, but I would love to read about what actually happens, in a scientific sense.
Thanks!

 

[CassCats]

Byron would know more, but just some digging myself and ive found this for you

USDA ARS Online Magazine Water Hardness Has Big Role in Fish Disease

For most people, the choice between soft and hard water for everyday use is a matter of preference or geography.

agresearchmag.ars.usda.gov

 

[kwi]

I did read this the other day.

One of the paradoxes in freshwater fishkeeping is that while most fish naturally from soft water environments will thrive in hard water aquaria, the reverse is almost universally not true. Tetras, Barbs, Gouramis, Corydoras catfish and Angelfish are all examples of originally soft water fish that are routinely and successfully kept in hard water community tanks. But Livebearers, Central American cichlids and Rift Valley cichlids almost never adapt to soft and acidic water conditions. In other words, if all you want is a mixed community tank, then hard and alkaline water will allow you to mix Platies, Neons and Corydoras without problems.

But don't know if there is any scientific basis for this or just anecdotal.

 

[CassCats]

And another good read.

FWHardness

 

[kwi]

And two articles on osmoregulation, the process involved.

Osmoregulation in Fish: Meaning, Problems and Controls (With Diagram)

ADVERTISEMENTS: In this article we will discuss about:- 1. Meaning of Osmoregulation 2. Problems of Osmoregulation 3. Factors Affecting Obligatory Exchanges 4. Osmoregulators and Osmoconfirmers 5. Osmoregulation in Freshwater Fishes 6. Osmoregulation in Marine Water Fishes 7. Controls. Contents...

www.yourarticlelibrary.com

Osmoregulation In Fish | Ionic Balance For Marine | Earth Life

Osmoregulation In Fish. It is easy to understand that fresh and marine waters do not have the same ionic balance.

www.earthlife.net

 

[2tank]

This is pretty cool to know

 

[FishFinatic77]

Thank you for all the links! These are really helpful!

 

[Essjay]

Byron has referred to a study done in Germany involving necropsy of cardinal tetras kept in hard water which showed calcium blockages in their kidneys.

 

[FishFinatic77]

Byron has referred to a study done in Germany involving necropsy of cardinal tetras kept in hard water which showed calcium blockages in their kidneys.

Do you know which thread that was in?

 

[Essjay]

Post #13 is one example

What kind of fish can I keep with my angelfish?

Pretty much what the title says. I just want to know what kind of fish I could keep with 5 angelfish. I'm aware that they're a shoaling fish so I've decided on a 75 gallon tank. I would really like to have a community orientated tank with lots of color, plenty of bottom feeders to eat the algae...

www.fishforums.net

 

[seangee]

I have stumbled across that article independently. As many of you may know I keep soft water fish in RO. My tap water is very hard and for years I thought that was ok as my fish were fine. I also thought the average lifespan of tetras was 12-18 months and used to spend a fortune replacing fish every year.

This year I lost the last of my glowlight tetras which started life in hard water and were switched to RO (gradually). They were all over 6 years old. I have cardinals that are a similar age and in recent years have only bought these to increase my group size. I know its not evidence - but based on my experience I will be sticking with soft water. Oh and the fish colours are noticeably more vivid in soft water.

 

[The Lumpfish Guy]

So I am going to jump in here because I have an opposing view to that of a few people on here
I have discussed previously that I do not believe that hardness is a big an issue as many make out to be;

The only papers I have found which have actually looked into the effects of water harness on fish has been in Tilapia (2 species plus hybrids), African catfish (plus hybrids), Salmon (Diploid and triploid) and Trout. Where growth performance was affected (still way above "natural") but no effects on measured welfare indicators including skeletal deformities, cataracts ect.

For example in Rainbow trout there has been some identification of parthenogenesis increases as found in the below study, there was only one correlation between hardness and any measured parameter of welfare measured, Cortisol (stress hormone). However when separated out by holding type eg cage and management style there was no association.

MacIntyre, C. M. (2008). Water quality and welfare assessment on United Kingdom trout farms.
El-Sayed, A. F. M. (2019). Tilapia culture. Academic Press. - tilapia reference too

The articles in this thread, only the first is a study, the others talk about osmoregulation but neither offer any references to back up their statements.
The first article links to the Paper published in Aquaculture here : https://doi.org/10.1016/j.aquaculture.2014.10.003
Now this study states that the Cations in the water are required for the bacterium to attach to the gills. While this is obviously bad for the fish the authors link to the parthenogenesis of the bacteria not a direct effect on the fish.

So while there is evidence that in many of the farmed species there is a potential for microbial risk, Hardness does not appear to pose a heath risk itself to these species.

There is some possible evidence that it could be more of an issue with juveniles
I have found a study which shows low growth rates for Angelfish in 300mg/L CaCO water concentrations. However the study did not find issues with any other tested parameter. The justification in the study was energy required to rebalance the ion loss through the gills. But the methodology is a bit odd and they didn't test for some things that maybe should have been ( possibly why it is in a bad journal and not cited at all!)
BONDRE, V. V. V. B. R., & BELSARE, S. (2007). Effect of water hardness on growth and survival of fry of angelfish, Pterophyllum scalare (Lichtenstein, 1823). Indian J. Fish, 54(4), 397-402.

A publication in the journal of fish diseases looking for dietary and water chemistry effect on hole in the head in discus found no relationship between water hardness and levels within the blood plasma, and no abnormal histology. ( Nor any hole in the head !)
Amesberger‐Freitag, A., Tichy, A., El‐Matbouli, M., & Lewisch, E. (2019). Hole‐in‐the‐head disease in discus fish, Symphysodon (Heckel, 1840): Is it a consequence of a dietary Ca/P imbalance?. Journal of fish diseases, 42(8), 1133-1142.

 

[mbsqw1d]

I know the question is specifically about hard/soft water, but PH has a big part to play, certainly in 'natural' water. PH doesnt always follow the law of nature with tap water as water companies supplement soft water with bicarb to raise the PH, in a bid to prevent pipe corrosion from what would otherwise have been soft, and therefore acidic water.

I'm not going to pretend to understand the majority of this:

physiology of fish at low pH: the zebrafish as a model system

Ionic regulation and acid–base balance are fundamental to the physiology of vertebrates including fish. Acidification of freshwater ecosystems is recognized as a global environmental problem, and the physiological responses to acid exposure in a few fish species are well characterized. However...

jeb.biologists.org

but it is evident that theres a decline in fish due to a decrease in PH in natural waters (acid rain).
From what I gather, this is partly due to the make up of fish gills (see ionocytes). The gills of fish who are adapted to acidic/soft water, don't 'work as hard' as fish who are not adapted to acidic/soft water. The gills of non-acidic dwelling fish develop more mucus, the gill structure deteriorates, and eventually the fish suffocates.

Thanks for asking the question @FishFinatic77 , some interesting reading afoot!

 

[The Lumpfish Guy]

The physiology of fish at low pH: the zebrafish as a model system Ionic regulation and acid–base balance are fundamental to the physiology of vertebrates including fish. Acidification of freshwater ecosystems is recognized as a global environmental problem, and the physiological responses to acid exposure in a few fish species are well characterized. However...

jeb.biologists.org

A peer reviewed piece of work

 

[FishFinatic77]

I know the question is specifically about hard/soft water, but PH has a big part to play, certainly in 'natural' water. PH doesnt always follow the law of nature with tap water as water companies supplement soft water with bicarb to raise the PH, in a bid to prevent pipe corrosion from what would otherwise have been soft, and therefore acidic water.

I'm not going to pretend to understand the majority of this:

physiology of fish at low pH: the zebrafish as a model system

Ionic regulation and acid–base balance are fundamental to the physiology of vertebrates including fish. Acidification of freshwater ecosystems is recognized as a global environmental problem, and the physiological responses to acid exposure in a few fish species are well characterized. However...

jeb.biologists.org

but it is evident that theres a decline in fish due to a decrease in PH in natural waters (acid rain).
From what I gather, this is partly due to the make up of fish gills (see ionocytes). The gills of fish who are adapted to acidic/soft water, don't 'work as hard' as fish who are not adapted to acidic/soft water. The gills of non-acidic dwelling fish develop more mucus, the gill structure deteriorates, and eventually the fish suffocates.

Thanks for asking the question @FishFinatic77 , some interesting reading afoot!

This is really interesting. Thanks for the link!