There are serious issues here, not only proposed but existing.
First, what are the source water parameters, being GH and pH? You already have fish species that are as opposite as they could be but there is some adaptability depending upon the numbers.
Second, on the angelfish. This is a big mistake. How long have you had the two together? How old/large are they? This is a fish that lives in small groups in their habitat. In an aquarium they will establish an hierarchy fairly quickly after being put together, and "intruders" are not likely to be tolerated. The two you have may suddenly decide to separate, leaving one dead very shortly, depending upon their gender and individuality. A corner 190 liter is way too small for this fish.