they will be fine I am sure, angel fish are territorial so as long as they have there own space should be ok
I love my glass catfish! They are really very easy to care for, just make sure you get more than 4 or 5, because they are a fairly timid shoaling fish, keep their water parameters good (i.e. in a cycled aquarium with ammonia 0, nitrite 0, and nitrate 5-20), and feed them well. I feed mine freeze-dried daphnia and bloodworms which they go crazy for, as well as a basic tropical pellet. They were a bit timid at first, but now they are very active and love to explore my tank!
Be careful you don't overstock, as an Angelfish is enough to max a 29 on it's own though I guess if there weren't territory issues and you kept the water good you would be ok