Can fish survive at ph of around 4?

[Lakshen99]

Hi I just tested my aquarium's ph and got a reading of around ph 4. This was using a newly bought cheap ph pen from china. Tap water is ph7 and when tested, i do get 7. My tank is co2 injected btw. Can fishes even live at this ph level? My fish are doing fine, no signs of stress. Maybe my ph pen is wrong?

 

[Byron]

It depends upon the fish species. Most soft and very soft water species from South America for example live in watercourses with a pH in the 4-5 range. But fish like livebearers that require moderately hard or harder water with a correspondingly higher (basic above 7) pH will not last long.

CO2 will acidify water, lowering the pH. As will the natural organic decomposition in the substrate. Very soft water fish will have no issue with this.

 

[GuppyBreeder180604]

yes, there are plenty of fish species that can not only survive but thrive on a Ph of 4, these fish are fish that come from swamps, bogs, mires, or the main rainforest waterways like the rio negro so they are things like tetras, anabantoids, plecos, snakeheads, new world cichlids, etc. just make sure to do your research since not all the fish in these groups like a Ph that low, but plenty do!

 

[Utar]

I am curious about tap reading 7ph and aquarium water reading 4ph. This means that from the tap to the aquarium there is a drop of 3ph. How are you going to maintain a constant ph in your aquarium. Its not good for any fish to experience large changes in ph. I guess what I am asking is how are you going to control the ph, because when you do water changes from a 7ph tap into a 4ph aquarium the mixture of the two will raise the ph. Then over time the ph will again lower. Your fish will be constantly subjected to ups and downs in ph.

 

[Byron]

I am curious about tap reading 7ph and aquarium water reading 4ph. This means that from the tap to the aquarium there is a drop of 3ph. How are you going to maintain a constant ph in your aquarium. Its not good for any fish to experience large changes in ph. I guess what I am asking is how are you going to control the ph, because when you do water changes from a 7ph tap into a 4ph aquarium the mixture of the two will raise the ph. Then over time the ph will again lower. Your fish will be constantly subjected to ups and downs in ph.

This would seem the case, but in fact it is not so in many situations. I have a pH of 7.0 to 7.2 in my tap water, and my tanks all run below pH 5 (can't measure lower, so no real idea). A 75% water change occurs once each week, and has for years now. I was curious as to how the pH would change, and testing before/after indicated a minute change that was temporary (couple hours). Once you have an established biological system in the aquarium, it rather governs itself.

The one thing here though is the reason for the pH of 7 in the tap water. In my case, it is not "natural," but induced with the addition of soda ash. The GH and KH of the source water is zero so there is no buffering. The aquarium system does the buffering, and the soda ash dissipates out rapidly. If I were to be doing such massive water changes with water having a substantial GH, KH and high pH, that would be a different matter. But then, if I had that type of water, I would not be keeping very soft water fish anyway, without RO or similar.

 

[Avel1896]

Hi I just tested my aquarium's ph and got a reading of around ph 4. This was using a newly bought cheap ph pen from china. Tap water is ph7 and when tested, i do get 7. My tank is co2 injected btw. Can fishes even live at this ph level? My fish are doing fine, no signs of stress. Maybe my ph pen is wrong?

Maybe... How much CO2 (bubbles per minute) do you inject ?

 

[NannaLou]

I am curious about tap reading 7ph and aquarium water reading 4ph. This means that from the tap to the aquarium there is a drop of 3ph. How are you going to maintain a constant ph in your aquarium. Its not good for any fish to experience large changes in ph. I guess what I am asking is how are you going to control the ph, because when you do water changes from a 7ph tap into a 4ph aquarium the mixture of the two will raise the ph. Then over time the ph will again lower. Your fish will be constantly subjected to ups and downs in ph.

Can I ask a question about keeping the water 100% ‘the same’ temperature/ph etc...?

I totally understand that in enclosed water spaces (tanks) that things are going to be different than in natural waterways, but surely then even parameters will change..? I’m thinking really heavy rain - surely this will change the temperature/ ph..? A lot of the places fish originate from will probably be experience monsoon type rainstorms..? Does this negatively affect the fish in the wild..?

 

[itiwhetu]

4 is too low for fresh water fish. Anything below 6 is not desirable.

 

[GuppyBreeder180604]

4 is too low for fresh water fish. Anything below 6 is not desirable.

well, lots of fish from the amazon and southeast asian swamps live in a Ph of 4 or even 3

 

[Colin_T]

Reduce the CO2 and add some carbonate hardness buffer so the pH sits a bit higher.

While most blackwater fishes from the Amazon can live in water with a pH of 4.0, they don't normally live in it all year round. When the wet season starts and the rivers fill up and flood the banks, the pH sits between 6.0 & 7.0.

 

[Avel1896]

4 is too low for fresh water fish. Anything below 6 is not desirable.

No, not at all. Many Southeast Asian fish need very low pH and conductivity, especially many wild Betta, Betta brownorum for example.
Others like Betta mahachaiensis prefers ans needs hard water conditions.

 

[Byron]

Can I ask a question about keeping the water 100% ‘the same’ temperature/ph etc...?

I totally understand that in enclosed water spaces (tanks) that things are going to be different than in natural waterways, but surely then even parameters will change..? I’m thinking really heavy rain - surely this will change the temperature/ ph..? A lot of the places fish originate from will probably be experience monsoon type rainstorms..? Does this negatively affect the fish in the wild..?

A very good question; my comments are in reference to tropical regions of South America as I have researched those in grater detail, but apply to SE Asian habitats too.

It is impossible to underestimate how close the relationship is between fish and their environment. This means that any change in the properties of the water around a fish has an immediate and profound impact on its physiology. Fish are much more vulnerable to the changing state of their environment than are terrestrial animals. The natural aquatic environment is generally quite stable. Water has a number of properties that, in general, ensure that changes occur very slowly, thus allowing fish time to adjust their physiological functions.

Environmental pH levels remain fairly constant throughout the year. The same is true for temperature. Terrestrial daily temperature ranges of up to 15C/27F are not unusual, whereas water temperatures will vary by no more than 3-4C/5-7F. Seasonal temperature changes occur slowly over a period of months. Fish have thus evolved in an environment where these values remain relatively stable and any changes that do occur, do so slowly.

 

[NannaLou]

A very good question; my comments are in reference to tropical regions of South America as I have researched those in grater detail, but apply to SE Asian habitats too.

It is impossible to underestimate how close the relationship is between fish and their environment. This means that any change in the properties of the water around a fish has an immediate and profound impact on its physiology. Fish are much more vulnerable to the changing state of their environment than are terrestrial animals. The natural aquatic environment is generally quite stable. Water has a number of properties that, in general, ensure that changes occur very slowly, thus allowing fish time to adjust their physiological functions.

Environmental pH levels remain fairly constant throughout the year. The same is true for temperature. Terrestrial daily temperature ranges of up to 15C/27F are not unusual, whereas water temperatures will vary by no more than 3-4C/5-7F. Seasonal temperature changes occur slowly over a period of months. Fish have thus evolved in an environment where these values remain relatively stable and any changes that do occur, do so slowly.

Thank you for that very informative reply

 

[Slaphppy7]

A very good question; my comments are in reference to tropical regions of South America as I have researched those in grater detail, but apply to SE Asian habitats too.

It is impossible to underestimate how close the relationship is between fish and their environment. This means that any change in the properties of the water around a fish has an immediate and profound impact on its physiology. Fish are much more vulnerable to the changing state of their environment than are terrestrial animals. The natural aquatic environment is generally quite stable. Water has a number of properties that, in general, ensure that changes occur very slowly, thus allowing fish time to adjust their physiological functions.

Environmental pH levels remain fairly constant throughout the year. The same is true for temperature. Terrestrial daily temperature ranges of up to 15C/27F are not unusual, whereas water temperatures will vary by no more than 3-4C/5-7F. Seasonal temperature changes occur slowly over a period of months. Fish have thus evolved in an environment where these values remain relatively stable and any changes that do occur, do so slowly.

And, in Nature, fish can migrate to waters that are more suitable for them, temperature-wise and chemistry-wise.

In our tanks, they cannot.

 

[seangee]

This would seem the case, but in fact it is not so in many situations. I have a pH of 7.0 to 7.2 in my tap water, and my tanks all run below pH 5 (can't measure lower, so no real idea). A 75% water change occurs once each week, and has for years now.

My own tanks display similar behaviour and I also change 75% weekly. My "tap" pH is 7 but KH and GH are 0 (its RO water not really tap water).

Be wary of those pH pens. They do work but they require calibration against liquids of a known pH. Most pens sold in the UK don't mention this and don't supply these liquids. So if you are lucky they may be accurate for a short period. But you have no way of knowing if you are lucky or rnot.