For a 55g tank, three to five Lionheads........OR........two Orandas.......Use pea gravel from Home Depot, really inexpensive($4 for 25lbs........)Get a bunch of fake tall plants---Vallisernia, Hornwort.............If you can afford it, get a system for live plants--CO2 and light fixtures..........Filtration, an Aqua CLear 101($79.99)........Do 50% water changes every week........
Orandas are capable of living as long as singletails do although other variants may not.
As far as CO2 is concerned, I don't encourage that for goldfish tanks. Goldfish need plenty of oxygen. CO2 defeats the purpose why we aerate our water properly in order for the fish to thrive. A low tech plant setup works better for goldfish than high tech setups do. And several variants of goldfish are quite capable in damaging several plants. Anubias, Java ferns, vallisnerias, cryptocorynes and Amazon swords are most likely to survive however several others including duckweeds, salvinia and Egeria densa probably won't.
Ideal temperature range for fancies should be 72-78 degrees Fahrenheit. Singletails are much more tolerant to colder temperature though.
I like goldfish a lot, just like some other fish more so I don't have the tank space. You can keep other fish with them...minnows and danios seem popular, dojo loaches, hillstream loaches, etc. A lot of barbs can tolerate lower temps but you just want to make sure they aren't too nippy.
I wouldn't bank on hillstream loaches to be very compatible with goldfish. Yes, they tolerate cold temperature range but they are unlikely to tolerate the lack of much needed currents that is part of their comfort. Neither will the goldfish tolerate the high currents so there is no compromise to allow these two to work together.
I don't encourage mixing barbs, minnows and danios with the fancy varieties. A lot of fancy varieties are too slow to be able to outcompete the rest of their tankmates for foods. The singletails may likely work but they'll eventually gobble their smaller tankmates.
Bristlenose plecos and dojo loaches though fit the bill quite well and can definitely be combined with any goldfish with no issues.
Thanks for your input guys, especially Lupin! I'm thinking of maybe an oranda and some clown loaches. Would that work? I have two already and I'm planning on getting them about 3 more friends. They are currently about 3".
Although you can allow it with temperature overlapping as a compromise, I don't personally recommend combining clown loaches and orandas. Your orandas will only feel harassed by the clown loaches' constant "whiskering". I tested my yoyo and clown loaches once (as I was moving them around and with impatience, decided to move in the goldies) with the fancies and they seem very unhappy with them constantly following and "whiskering" them around prompting me to move the loaches out. Dojo loaches remain the best option you have as they mingle better and do not bother their tankmates in any way that they can.
