Weii I suppose my first official fish was a goldfish I won at the fair when I was very young. It lived happily in my mum's baking bowl for a couple of weeks then we bought a proper bowl and moved it. It died the next day. Totally clueless.
Then over a year ago my husband brought in a 4' tank with fish which after some investigation I discovered to be a silver shark, a rainbow shark, an angel fish, a common plec, a pearl gourami, a black widow and another one I never found out. I think the rainbow shark was the first to go, he had an ulcer on his side when we got the tank, the random unknown went next after we cooked the tank, the silver shark succumbed to velvet, the black widow was rehomed (prob lucky for it), the angel died mysteriously when we went away for the weekend. The plec and the pearl gourami we lost in the last couple of months, they had a hard life.
The first fish I officially purchased were 4 golden barbs around a year ago, they're still going strong. Just a shame we didn't learn about tropical fish before getting teh tank.