Nice goku.....
Well I will make this assumption: the oranda is still small and not going to be in same community.....
So he gets to move to the 10 a while; when your community moves to the 55?
For a cheap
QT if you are more willing to be patient to avoid a large layout;
you get a thermal compact
(hagen. largest expense for your QT but it is a good back up) 25 watt and
put that in a 6-7 dollar 3 gallon kritter keeper (5 is better).
Get a throwaway 3 dollar filter that is good for about 3 weeks (perfect for long
QT as I do or short)
You get a cheap airpump or split off one you have if it can power it.
You can
QT about 3-4 same type fish in the 3 gallon.
Now to start getting animals in sets of 3-4 that will go nicely in your 55.
You probably cannot get more than 8-9 fish of any type for a 10.
Depends on just how soon you truly expect to get your 55.
I cannot suggest many species with confidence since my speccialty is in labyrinth fish and some of goldie and a wee bit pirahhna.
AS far as my experience goes; your oranda really needs to be alone in the 10 gallon or with another fancy if you want to keep it vital and get those really amazing colors to show. And really will need eventually a pristine kept 20 minimum for himself and a 30 for him and goldie companion. Heck I think the loose rule of thumb for goldies now is like 8 gallons per inch of fish? :?
Not to mention it really
isn't that good to mix goldies with tropicals because many species like it warmer than a goldfish will tolerate. I suppose a half dozen cloudfish or certain guppies coud be okay if they are not nippers.
A person that knows those breeds better can say.
Also a nixing for mixing, goldies need monster filtration and some current to be happy, many small fish may not like current. I found them to be high maintainance fish when I used to help my grandfather with his prizewiners. I love to look at them but I will NEVER own one because of that. Unless I have a pond
One last note..before buying a single fish more..but a reliable brand test kit.
Your tapwater readings may narrow the field and make deciding easier.
And it is the number one tool of any fishkeepers toolkit!