Do water parameters matter?

[Fishkeeper123]

First of all I’m not talking about ammonia, nitrite, nitrate. I mean hardness. For example, when I first started it occurred to me that the water I lived in decided which fish I kept. But does water parameters actually matter for shop bought fish? For example, Bristlenose plecos were originally soft water fish. However I wouldn’t hesitate to recommend them to someone who has hard water.(like 12dgh) There are extremes which I wouldn’t do like a licourice gourami in really hard water and a shell dweller tank in really soft water. But altering the water of fish can cause more problems as it’s inconsistent. What are everyone’s thoughts? This was raised in a few threads so wondering where people stand.

 

[Magnum Man]

I killed a lot of angel fish, all domestic bred, when I was only using my hard water, so I would expect it varies by fish, some likely live in water that varies between dry and rainy seasons

 

[gwand]

High calcium and magnesium can cause slow but steady decline in kidney function in soft water fish. Their lifespan is shortened. I have observed this damage under my microscope. Tank raised soft water fish will suffer the same fate as wild caught soft water fish unless selectively bred over many generations to tolerate hard water. Hard water fish require high calcium and magnesium as well as other cations for normal heart and kidney function. Subjecting East African cichlids to soft water is a bad idea. Now I admit there are exceptions to this paradigm. Exceptions within a species and between species. However my philosophy is not to risk that a fish is the exception to the rule. Especially when I often spend $55 to get a wonderful fish shipped to me. Let alone the cost of the fishes themselves. On another philosophical note, some people don’t care that a fish live 1-2 years rather than seven years. In that case my argument is moot.

 

[seangee]

I believed that and for many years kept my favourite cardinal tetras (along with other soft water fish) in hard water. And of course this was supported by the LFS experts. My fish appeared to be healthy and in good condition.
The LFS was all too happy with my annual visit to replenish stock, after all these are little fish and only have short lives. At the time the average life of my cardinals was 12-18 months.
One day I visited a friend who kept similar fish in the midlands, where they have very soft water. I immediately noticed his fish were much brighter than mine. When I mentioned the short lifespan he was shocked.
Long story short - I switched to RO and today the usual lifespan of my tetras is 6 years plus. They were literally dying of old age (organ failure) well before their time.

SInce you mentioned bristlenoses, and in another thread too, I suspect these are fish that have evolved to survive a much wider range of conditions. I had a bristlenose that lived for 20 years. For the first 12 of those he lived in my tap water which is hard enough to walk on. For the next 8 he lived in very soft water.

As an aside I once spoke to an employee at a well known local chain store who is also a local breeder. In the store they always tell you that the wild caught SA fish have been hardened up. What this actually means is that they are thrown into tanks with hard water and left for two weeks. What doesn't die is sold as hardened. In practice in my area the mortality rate is higher than 70% - and of course this is built in to their pricing.

 

[MaloK]

I found out that the ratio between magnesium and calcium was more important than total hardness.

Adding magnesium to a too rich in calcium source can have more positive effects than diluting it with demineralized water and end with even more unbalanced water.

 

[jaylach]

I try to have all fish in a tank be in the same hardness range but will stretch things a bit. For instance I plan on having Panda Garra and Ember Tetras. Going just PH since I won't get a good idea of GH/KH until the tank is up and running I will be running on the edge. The PH of my tap water varies between 6.3 and 6.7. 6.5 is the low end for Pandas and the high end for the tetras so I will be on the line as to the fish matching the water but I don't really think being off 0.2 back and forth is a big deal since the average will be within range for both fish.

Now, I used to do pretty much S.A. Cichlids and would have never considered adding hard water African cichlids as it would just result in a short life for the Africans.

I guess what I'm saying is that I don't think the water hardness/softness has to be exact for each species but it should be as close as possible.

 

[sharkweek178]

I never believed the idea that fish would just adapt to non-compatible hardness by being bred into it in captivity. As if a few generations of breeding would overcome millions of years of evolution.

 

[jaylach]

I never believed the idea that fish would just adapt to non-compatible hardness by being bred into it in captivity. As if a few generations of breeding would overcome millions of years of evolution.

Sure, soft water fish could become tolerant to hard water; that is called evolution, but it could never happen in a few generations. It would take thousands of generations, possibly hundreds of thousands.

Can fish change what they need? Of course they can but it takes ages. Take Lake Erie that is the Ohio northern border. There is an area under the lake that is mined for salt by Morton Salts. This indicates that, way back when, the Great Lakes were actually an inland salt sea that would, naturally, have beasties that like salt. Yet today lake Erie thrives with fresh water fish. So, yes, fish CAN adapt to sever changes but it takes ages, even millions of years. Not something that is about to happen in a fish store.

 

[MaloK]

I disagree, evolution makes every generations completely adapted to the current environment.

But Environment normally are not changing fast... or it causes extinction.

But atm there's everywhere in the world an unknown number of tanks. That contains bullet proof nitrate resistant strains of many life bearers.

 

[jaylach]

I disagree, evolution makes every generations completely adapted to the current environment.

Sorry but that is just not true. The evolution process can take millennia. Mayhaps I'm missing what you are trying to say but throwing enough salt into a fresh water tank to kill most but not quite all the fish will not result in the fresh water species being fine in salt even if they were to survive long enough to breed.

 

[CassCats]

Columnaris bacteria is more prevalent in hard water.

Fish that evolved in soft water aren't as immune to it and are often more likely to succumb to worsened, more fatal infections.

Fish Reared in Hard Water are More Susceptible to Columnaris Disease : USDA ARS

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

Bacteria levels tend to be lower in soft, acidic water and the more acidic the environments, the less of these bacteria thrive... but then the fish who come from these habitats are thrown into environments favorable for these bacteria, cannot cope with them and will die off quicker and easier.