Hi DaveW
It sounds to me like the experience smithrc had with his adolfois was one that could have happened with any kind of wild caught cory. I don't think C. adolfoi is any more delicate than most corys.
What often happens when you buy fish from a lfs, is that they have just been shipped in and have not yet had a chance to recover from their grueling journey. From the time they are scooped out of their river they have passed through a number of different tanks in various places. During the process, the pH might have been different, they may or may not have been fed, the temperature has fluctuated. They have also been crowded in together for extended periods of time.
By the time they finally reach your lfs, they are usually, to some degree or other, suffering from either disease or chemical poisoning, maybe both. Probably there are some that have not survived, and your lfs staff has removed them. If they look good, they probably are good, but not always. Sometimes they just can't manage another change in water, or are so weakened by the trip that they fall ill to some bacteria that the fish you already own are immune to. There is always that risk to take when you buy wild caught fish.
So what can you do? There are two things. First, you can avoid buying them when they first arrive at the lfs. If you have a reliable seller, he will be honest with you and tell you what you need to know to make a wise decision. In time, they will either stabilize or die in his tanks, rather than yours. This is where my advice usually ends for the hobbyist.
But I know that smithrc is a little further into fishkeeping, so I will go on a bit more. If you want to be certain of getting a fish that is unusual and might not be seen again in your area, you can buy them and try to restore their health yourself. This is where a quarantine tank comes in. I would not suggest buying any fish that already looks bad, for example, if it is gasping for air at the surface, very pale, shaking badly or swimming erratically. They don't have much of a chance. A fish with a little fin rot can make it, and so can others that have just been mildly effected by the trip.
Before doing anything, I will put this kind of fish in quarantine and feed them lightly for a few days, while watching them closely. A tsp. of aquarium salt per 10 gallons of water often eases their transition. An airstone, to increase the oxygen content of the water is sometimes helpful too. Then, if medication is needed, it can be given. Often, lots of clean, fresh water and good nutritious food will be all you need to do. It might take a few weeks until you are sure they are OK to go in a tank with your other fish, but IMHO, it's often worth the effort to get a special, hard to find, group of corys.
