A pond needs the same sort of maintainance an aquarium does (just on a larger scale). And unless you only keep one goldfish in there, you end up with the same problem: more goldfish than you can handle. There's no reliable way to sex young goldfish, and happy pond goldies breed, and breed, and breed...
Keeping the fish on the 55 gallon tank is probably the best solution for now, unless the OP wants a pond for other reasons.
Keeping the fish on the 55 gallon tank is probably the best solution for now, unless the OP wants a pond for other reasons.