I don't remember for sure but I think it was Neon Tetras. When I was about 14 I had a tank in my bedroom for a couple years. I had neons, a BGK, small bala shark, and a few others. I didn't really know anything about them as far as sizes because I had them all in a 20g. I did do regular water changes and filter upkeep. This was about 1995 in NY and I'm now a lot older and in California.
Of my newest batch the first fish were goldfish. My fiance had to save those poor feeder fish :-/ We filled up a 55g (fills up quick with goldfish although they are moving to a pond once we get a house). Then we wanted more fish and I wanted non goldfish so we setup a small 20g with tropicals. Of them the first in there was a dwarf gourami and some harlequin rasboras.