What are soft water fish sensitive to?

Joshaeus

Member
Hi everyone! I understand that soft water fish (licorice gouramies, tetras, etc) are quite sensitive to excessive KH (or, in some cases, ANY KH) in the water. However, are they as sensitive to GH or other non-KH substances in the water? For example, would a TDS of 50 ppm, primarily comprised of small quantities of fertilizers added to distilled/RO water, be an issue for keeping and/or breeding soft water fish so long as the KH and PH are within a good range? Thanks
 

MacZ

Member
I think it will only be a bigger issue with wild caught specimen. Tank bred individuals should be adaptable.

Otherwise, it depends a lot on the provenience of the fish. Fish from the Congo basin should be accustomed to different minerals and metals in the water than fish from Sumatra or the Amazon basin. As you bring up fertilizers, I'd expect a higher sensitivity to Nitrates.
 
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Joshaeus

Member
MacZ said:
I think it will only be a bigger issue with wild caught specimen. Tank bred individuals should be adaptable.

Otherwise, it depends a lot on the provenience of the fish. Fish from the Congo basin should be accustomed to different minerals and metals in the water than fish from Sumatra or the Amazon basin. As you bring up fertilizers, I'd expect a higher sensitivity to Nitrates.
Yeah...as I am not so sure whether a nitrogen cycle would establish itself in a tank with little to no KH, I might skip on dosing nitrate entirely and let the plants subsist on the ammonium produced by the fish in such a scenario.
 

MacZ

Member
Fertilizers and low-pH biotopes don't mix anyways. One of the main attributes of these biotopes is an extreme lack in nutrients. If any fertilizers I'd go with root tabs or dirt/soil under a layer of sand on top.
 

Islandvic

Member
I dont think "soft water fish" are entirely dependent on living healthy lives in water that matches exactly where their species originated from.

For example, my Tetras and SA cichlids do just fine in our water with 7.8pH, high TDS and hard water.

Jason from the Prime Time Aquatics channel YouTube lives in the greater Chicago area and has hard water with a pH of 7.8-8.0, yet he successfully breeds healthy SA cichlids.


 

chromedome52

Member
A TDS of 50ppm is still relatively soft water, so it's not going to interfere with most softwater fish. "Soft" and "Hard" are relative terms, and two of the most abused terms in aquaristry. I've seen personal ideas on what constitutes each, but never a solid point where one becomes the other. Many species live in a zone that I call "moderately hard", and this is where most aquaristry takes place. I put this between 100ppm and 250ppm TDS. However, this can waver with high Calcium content (KH).

Chicago city water system draws from Lake Michigan. The hardness is usually about 150-170 ppm TDS, and I have no clue what the alkalinity is because I've never tested for that. I'm reasonably sure it's fairly low. The pH runs from 7.5 to about 8.0, depending on various things. When I was using Benton Harbor city water - also drawn from the Lake - these were approximately the same parameters that I had to work with. I bred a few easier Tetras in this water, tons of Killifish and numerous SA Cichlids such as Apistos. But I also bred livebearers quite easily, and the few East African Cichlids that I kept had no problems breeding in it, either. I bred a couple of Pseudotropheus species, Cyrtocara moorii, and some of the Victorians. I called it "Lake Michigan Magic Water" because I could breed just about anything in it. However, there were still a few fish that called for special conditions. I had to use peat filtered DI water to breed Lemon Tetras. Apistogramma agassizi would spawn but the eggs didn't hatch. The Gold Ram eggs did, though.

30 years ago I moved to a more rural setting with a well, in an area where the average well water has a TDS of 400-600, most of that being Calcium based (KH), and a pH around 8.5. I've had to adapt. I used straight well water for Swordtails and a few other livebearers, they loved it. Malawi Cichlids...did not. Tangs did alright, though. Believe it or not, R/O is not a magical cure for hard water. Being on the downwind side of Lake Michigan, I was able to get by for many years by collecting Rainwater and filtering it through peat, but this can also be troublesome in a dry year. Using a combination of sources, both Rain and R/O, mixing with the well water, I can usually find what I need to get fish breeding.

So why did I tell you all of this? To point out that I've had to experiment a lot to find the right conditions for breeding some fish. Your common aquarium fish are, indeed, highly adaptable, but most really aren't soft water fish, or even really hard water fish. And as has been pointed out here at FishLore many times, there's a fine line between surviving and thriving. Cardinal Tetras are the best example of this. They will survive, have good color, and appear to behave normally even in moderately hard water, despite being one of the species that originates from genuinely super soft waters. However, they will never spawn if you raise them in water above 30ppm TDS. They will not be able to spawn later even if you give them the soft water. If they don't grow up in super soft water, they will never be able to breed. In my opinion, a fish that is prevented from breeding by the conditions under which they are being maintained cannot be described as "thriving".

Since my objectives in keeping fish always go toward breeding them, I have to find the right set of parameters for them. But even if you don't plan on breeding them, giving your fish the best possible situation for their health includes trying for those targets.
 

Nick72

Member
Joshaeus said:
Yeah...as I am not so sure whether a nitrogen cycle would establish itself in a tank with little to no KH, I might skip on dosing nitrate entirely and let the plants subsist on the ammonium produced by the fish in such a scenario.
My tap water comes out between 0-1 KH. My tank cycled in 20 days and the cycle has been rock solid for 14 months now.
 
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Joshaeus

Member
Nick72 said:
My tap water comes out between 0-1 KH. My tank cycled in 20 days and the cycle has been rock solid for 14 months now.
Thanks! My tests on my past blackwater tanks (all with virtually no hardness of any kind and with PH in the 4's or 5's) had been inconclusive...one such tank occasionally had a few ppm nitrate, another never had any. Seachem ammonia test kits did not seem to work in my blackwater tanks for some reason, so I could never ascertain whether they had truly cycled.
 

MacZ

Member
As far as I know for Ammonia tests you have to have a pH above 5. Instructions of mine say something like that.
 
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Joshaeus

Member
MacZ said:
As far as I know for Ammonia tests you have to have a pH above 5. Instructions of mine say something like that.
Good to know! Would simply adding some baking soda to the water sample and mixing it thoroughly solve that problem?
 

MacZ

Member
Joshaeus said:
Good to know! Would simply adding some baking soda to the water sample and mixing it thoroughly solve that problem?
I don't know, could be that the soda reacts with the ammonia, but technically... yes, raising the pH somehow without diluting should do the trick.
 
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Joshaeus

Member
MacZ said:
I don't know, could be that the soda reacts with the ammonia, but technically... yes, raising the pH somehow without diluting should do the trick.
They apparently do react, but not particularly readily;

Somewhat humorously, Ammonium bicarbonate is produced, not with baking soda and ammonia, but with ammonia and carbon dioxide. That substance is quite unstable, however.
 

MacZ

Member
Joshaeus said:
Somewhat humorously, Ammonium bicarbonate is produced, not with baking soda and ammonia, but with ammonia and carbon dioxide. That substance is quite unstable, however.
Doesn't backing soda produce CO2 when mixed with acids?
 
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Joshaeus

Member
It does...however, Ammonia is a base, not an acid.
 

MacZ

Member
Joshaeus said:
It does...however, Ammonia is a base, not an acid.
Yes, I was just referring, to your CO2-remark. So when you put baking soda in your acidic water the CO2 is released and reacts with the ammonia. Theoretically. But can this change readings I'm asking myself right now.
 

Nick72

Member
Joshaeus said:
Thanks! My tests on my past blackwater tanks (all with virtually no hardness of any kind and with PH in the 4's or 5's) had been inconclusive...one such tank occasionally had a few ppm nitrate, another never had any. Seachem ammonia test kits did not seem to work in my blackwater tanks for some reason, so I could never ascertain whether they had truly cycled.
My tap water 0-1KH comes out at around 6.8-7.0 PH, I suspect the water company is buffering PH with salts.

I do sometime see the PH drop after a few days, often down to around 6.5 (once went down to 5.6), but I've taken to using a bag of Crushed Coral near the canister output for the first 48hrs after a water change. I believe this increases my KH to around 2, and gives my a PH buffer of calcium carbonate.

I've just ordered a kg of CaCo3, and in future I will just add a couple of teaspoons of this in every water change - I'm already adding 6 teaspoons of Epsom Salts with every water change to increase GH.

I believe doing the above is both beneficial for my fish, and necessary for my plants.
 
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Joshaeus

Member
Nick72 said:
My tap water 0-1KH comes out at around 6.8-7.0 PH, I suspect the water company is buffering PH with salts.

I do sometime see the PH drop after a few days, often down to around 6.5 (once went down to 5.6), but I've taken to using a bag of Crushed Coral near the canister output for the first 48hrs after a water change. I believe this increases my KH to around 2, and gives my a PH buffer of calcium carbonate.

I've just ordered a kg of CaCo3, and in future I will just add a couple of teaspoons of this in every water change - I'm already adding 6 teaspoons of Epsom Salts with every water change to increase GH.

I believe doing the above is both beneficial for my fish, and necessary for my plants.
Agreed...magnesium especially is crucial to plants. Be forewarned that calcium carbonate does not dissolve in water very well (speaking from experience here).
 

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