Originally Posted by fishyfiona
p.s i have been reading that Angel Fish can live in groups or on their own ? was thinking of just keeping this one ? Would the danios upset the Angel with their speed, is that what you mean ? thanks so much !
Angels occur in large or small groups in nature; they have a social structure within the group, much like most cichlids (and many characins for that matter). It follows that they will be less stressed and more "comfortable" in a group. However, tank size is important. Many fish, and angels are no exception, can develop quite different behaviours when they feel "confined" and may become antagonistic to their tankmates. Besides this, other fish (many tetras) see their fins as easy nipping targets, and this stresses the angels. Stress in fish, as in humans, brings on immune system deficiencies and thus poor health.
While I would always recommend a group (3-5 in a 55g for instance, more in a larger tank), as I pointed out previously there are other considerations. A single angelfish in a suitable environment may well be happy. This definitely does not work with other shoaling fish like the characins (tetras, hatchets, pencilfish), where being kept singly, in pairs, or even 3-4 is known to cause considerable stress in the fish, simply because they are not in the environment that nature has programmed into their instinct. I am not a biologist, so I cannot say to what extent this occurs in angels. I am not one who believes that if the fish "looks" OK, it is OK; it may not be.
In spite of all this, in your case I would prefer to see the lone fish in your better environment; it will likely live longer and probably be "happier." Just choose its tankmates carefully. The danios might nip at its fins, and they are active. Angels and discus do not like active fish around them; discus will refuse to eat, but I don't know if angels exhibit similar traits. That's why the Hyphessobrycon species such as those in the Rosy Tetra clade are usually good tankmates for angels and discus.
I have a trio of Poecilocharax weitzmani in my 90g. Absolutely stunningly beautiful little fish, but very quiet and shy. They have been in this tank for more than a year now. But they still get frightened by the other fish, and I have nothing even remotely resembling "boisterous" in this tank. The P. weitzmani will only eat bloodworms (or live foods); I am careful to squirt the worms in front of them, but if another fish approaches, they turn and very quickly dart away, and I have to wait and try again. This is an excellent example of how "active" fish upset quiet fish.
Hope this helps a bit.