If you are going to buy goldfish for a Pond you want Comets, Commons, Shubunkins etc. Now while they certainly do get too big for a 20gal, thats going to take about 6 months. Move them into the pond then, and buy a couple more baby ones. After a couple of years you will have a fully stocked pond.
2 x 4-5" goldfish are OK in a 20gal, just they will get much bigger eventually. Growing goldfish in a tank for 6-12 months to give them a bit of size before moving them to a pond is perfectly fine.
Ian
2 x 4-5" goldfish are OK in a 20gal, just they will get much bigger eventually. Growing goldfish in a tank for 6-12 months to give them a bit of size before moving them to a pond is perfectly fine.
Ian