I was roughtly 13 when I recieved my first fishtank. It was a 5 gallon setup in Teal Blue color with the typical filter and such.
A friend happened to have a fish that was killing her guppies that she gave me. I didn't know what it was then (it was a Yellow Lab) so I put it into my tank. It killed all of my fish except for a small pleco.
I upgraded to a 10 gallon, and put a Black Moor
goldfish into the tank. The yellow fish chased it around, and continued to do so til I went to bed. I woke up the next morning, and they were both kinda hanging out. For the next few months, they lived together without any drama errupting. But, sadly, my Black Moor broke out with ick and my parents refused to let me buy the medicine for it, so it died. My yellow lab continued on until i bought a simmilar fish which ended up killing it 2 months later. After that, I stopped with fish.