Fish Psychologist anyone? (long)

I really do not know where to post this, so i try it here, if wrong.... sorry, move me around!

I had a VERY peaceful 175 liters tank with
2 goldfish, 6 white clouds minnows, 1 buenos aires tetra, 2 zebra danios, 3 pearl danios, 2 rosy barbs

It was heaven, only a few displays amongst minnows and danios, a few bumps into each other a few chases, lots of love and now I introduced a new goldfish...

He/she - let's call her Angie - is a beauty, is a meteor canary yellow, but she is a bully. That's her story...

I first got her with other fish (not the one in the 170 liters tank)
1 zebra danio, 2 buenos aires tetra and 3 red eye tetra

Put them all in a 120 liters tank and after a few days found the Angie's fins and a couple of the tetras frayed, so I observed the tank and before long saw that one of the BA tetra was stalking her, going very quietly behind her and attacking her without any provocation; and run away after a biting her fins. The same tetra would also swim faster than the others and bite the slower fish out of his way. Angie was very distressed, and it seemed that the other tetras were learning the stalking and biting behavior (possible?).

I separated the scoundrel in an emergency tank, and it seemed everything was nice and dandy in the 120 liters tank. But because it wasn't really fair to the BA tetra, being lonely and scared all the time, I gave him another chance, put it back in the 120 liters, and after 30 min he started all over the biting thingy.

Now different strategy, Angie and the danio got their own separate tank (danio too to give Angie a bit of company), results; the 120 liters is now property of 5 tetras that go along very well, and Angie and danio are fine together.

Or so it seemed, a few days ago I found the danio injured, and after a day he died. I do not know what happened,a freak accident? (now I think if it could have been Angie? possible?)

Anyway, this morning I add Angie to my 175 liters tank, thinking that the quarantine period is passed, better she stays with her kind of folk.

After a few min of adaptation she started to challenge Eira and Zap (the other two goldfish), and soon after started the biting, really looking for their fins, and also any other fish that swims around her.

Now.... what do I do?
Leave her there hoping she'll stop? It is an adjusting-to-new-environment behavior?
Will the other fish in the tank 'learn' to bite each other?
Is she better off by herself?
Have a tank with all the bullies and let them sort it out?

Hope I was clear enough, and sorry for long post... All insight are welcome!

ok only a few quick points, goldfish shouldnt be in tropical tanks as it speed up their metabolism and growth rate thus shortening their life span, also ba tetras are a shoaling species and like tiger barbs can be nippy if kept singly or in pairs so advice is either get rid of it or add 5/6 more so they'll spend more time chasing each other rather thn other fish, as for the other 2 goldfish they have probably made their territorys in the tank and the addition of a new fish has upset their territories, so change the decor around and it should hopefully change the situation as they will all have to set up new territories.

hope this helps
Seamus

Thank you Seamus for input,
1- the 175 liter tank is not heated at this moment, and all the fish are doing fine, when the temp. will go down I'll move the goldfish out and heat the tank.
2- strangely enough the ba tetra that i have by itself in the 175 l. is actually schooling (if not shoaling) with the danios, and no biting at all
3- the ba that I have in the 120 l. are schooling with the red eye tetra and - after i got angie out of there - going along well enough.
4- the 'original' goldfish in the tank are not bothered at all by angie, do not even fight back, just move out of her way
5- I did change the decor around a bit, not major, but there's not enough decor inside for big changes!