it is not easy to acclimate wild angels to tap water. However, there are a few folks around the world who are managing to spawn them. Tank raised Altums are way more hardy that wild caughts. My first load were all dead in about three weeks. I learned then I needed to create a brand new tank for them. I could not use anything taken from another established tank.
Fish which come out of such acid waters have an edge relative to bacteria diseases. Many bacteria cannot live in acid waters. So the Altums may niot have any real immunity to some things. The stress of foing into radically different parameters can also mean radically diffferent diseases/parasites may await them and further, what they bring in will be pretty alien in respect to aquarium life.
Next, at the point I started with Altums one of the biggest issues was with the importers. When the came in they went into water not at the proper parameters and not isolated from pother potential problems. So what we keepers were able to get were not in the best of shape. They were extremely hard to keep alive. The staff at Finarama worked with a few importers and even exporters to try to remedy the problems. There was a certain amount of success and over time the survival rate for some imports got much better.
The Altums I now have are tank bred in the USA, They are pretty fish and a lot more hardy than wild imports. The one thing I will never have but wich I want more than any Altums are the ones bred by Simon Forkel in Germany. If you have not seen either of the following vids, the second one is shot mostly at his facility, The fish are so lovely it almost makes one cry. They should be watched in order.