Well when I was young around 8-9 we had the stock standard goldfish in a 3ft tank. I was obsessed with fish and used to draw pictures of fish and fish stores etc.
Fast forward a couple of years and our goldfish had died and I went with my birthday money to a (bad) fish store and twice got extremely poor and expensive advice. That turned me completely off fish keeping for years as I felt terrible constantly killing off my fish.
When I was 20, my dad moved to Canberra and left his goldfish with me. That was enough to get me back into fish and so I have around three years of actual experience now that I am 23. Thankfully, I am a lot better at keeping my fish alive this time around thanks mainly to the easy accessibility of the internet.
It's why I think in this day and age there is no real excuse not to do research before you go out and buy.