OK, I've a general interest question about fish and their particular pH requirements. I'm preparing to restock a recently (heavily) replanted 55 gal. tank, and am genuinely puzzled about the water parameters listed by online suppliers. I get that these might be rules of thumb, but how accurate are they in general?
Several examples: because of a whole house water softener and iron treatment system, we have odd water parameters- pH consistently 8.4, GH 4 (German units, sorry) and KH 11-12.
I didn't even learn about GH and KH until I started research to restart the tank, and realized that years ago before the internet I struggled mightily with pH, and probably hurt more fish than I helped trying to reduce it w. liquid additives which many pet stores pushed.
At that time among other things we stocked Corys (julii, I think) and Silver Hatchets. One of each has survived the intervening years of neglect. Some online retailers don't list water parameters (warning sign?), but those that do list the high range for some Cory species at c.7.6-7.8, and Hatchets at 7.0.
I'm sure this is all extremely complicated, but were these little survivors just outliers that somehow managed to adapt? I assume that some fish might be more adaptable than others- are there any good bets? Or is acclimatization even to a somewhat extreme environment something that most fish can do?
Of course the fish we're most interested in are mostly South American soft-water types like the hatchets, tetras (esp. tetras), Corys, and Rams...
I don't want to kill fish needlessly (and waste money), so any advice would be immensely appreciated.
Bump: Sorry for the verbose wandering. My questions in summary:
* Are the water parameters listed by retailers for fish reliable?
* Is there a reliable, unbiased source online for species requirements?
* if the requirements are accurate, are many fish adaptable to parameters outside their listed "comfort zones", or is this more likely to be random, in individual fish?
* Are there many species more adaptable than others?
Thanks again (and, for the record, I'm not at all interested in the African cichlids which might be happy with my odd water, so...)