Need your opinions on my cory situation

[Byron]

Ok. This makes a lot of sense. What I am understanding from this is that you can never go wrong matching the parameters of your tank to what the fish would naturally be in out in nature.

Absolutely, no question. If you can provide comparable parameters to their habitat waters, the fish will without question be in a better position to be healthy.

You also point out that because of breeding and such in captivity and most likely in waters that do not completely match that of those in their wild habitats that it is possible they are able to do well in a lower GH and there is potential overlap in the adequate GH for both species. Am I understanding this correctly?

This is the general held view among many biologists, but it cannot be taken at face value. Very few species can adjust to significantly varying parameters to such a degree that the parameters make no difference. Evolution can result in this over many years. And some species do seem to have a higher tolerance than others. Unfortunately, none of us can talk to a fish to see how it actually manages. And this is not being silly--the fact that a fish "lives," eats and even spawns in water having different parameters from its natural habitat does not for one minute mean the fish is not being somehow impacted. Even longevity is not always a reliable guide. The will of a fish just like any animal to survive and reproduce is very strong, and the fish will try to manage. This has a weakening effect on the physiology however, most of the time.

As far as I can tell, if someone WERE to match the tank’s parameters to suit both fish, they would want to aim for a GH of 7. Does this sound about right? I want the fish to be able to thrive.

This is where it gets difficult. Survival is uppermost to the fish, as I pointed out above. The extent to which the fish merely survive as opposed to thrive is not easy to see; there is plenty of evidence that the fish may outwardly behave the same regardless, but that does not mean it is able to manage without problems. If we could talk to the fish we could likely be certain here, but we cannot. And regardless of what anyone thinks, you just cannot use the outward appearance as a certainty that things are OK.

I would aim to provide more for the pygmy cories here than the guppies. But that means I would never combine the two. I am not going to knowingly subject guppies to very soft water. But I will also never increase the GH with cories beyond the lowest GH I can provide realistically. Ian Fuller told me there is no question but that pygmy cories are best in basically RO water, and that is what he provides to spawn this and other wild caught species. I am lucky to have this come out of my tap, and I do nothing to increase GH/KH or pH. All of my fish have similar needs, I just will not acquire fish that need "harder" water, period.

 

[OliveFish05]

Absolutely, no question. If you can provide comparable parameters to their habitat waters, the fish will without question be in a better position to be healthy.



This is the general held view among many biologists, but it cannot be taken at face value. Very few species can adjust to significantly varying parameters to such a degree that the parameters make no difference. Evolution can result in this over many years. And some species do seem to have a higher tolerance than others. Unfortunately, none of us can talk to a fish to see how it actually manages. And this is not being silly--the fact that a fish "lives," eats and even spawns in water having different parameters from its natural habitat does not for one minute mean the fish is not being somehow impacted. Even longevity is not always a reliable guide. The will of a fish just like any animal to survive and reproduce is very strong, and the fish will try to manage. This has a weakening effect on the physiology however, most of the time.



This is where it gets difficult. Survival is uppermost to the fish, as I pointed out above. The extent to which the fish merely survive as opposed to thrive is not easy to see; there is plenty of evidence that the fish may outwardly behave the same regardless, but that does not mean it is able to manage without problems. If we could talk to the fish we could likely be certain here, but we cannot. And regardless of what anyone thinks, you just cannot use the outward appearance as a certainty that things are OK.

I would aim to provide more for the pygmy cories here than the guppies. But that means I would never combine the two. I am not going to knowingly subject guppies to very soft water. But I will also never increase the GH with cories beyond the lowest GH I can provide realistically. Ian Fuller told me there is no question but that pygmy cories are best in basically RO water, and that is what he provides to spawn this and other wild caught species. I am lucky to have this come out of my tap, and I do nothing to increase GH/KH or pH. All of my fish have similar needs, I just will not acquire fish that need "harder" water, period.

Thank you, this thoroughly answered all of my questions. I appreciate you taking the time to give me such in depth answers.