I suppose I should admit I cycled my first fish tank with fish, but it was an emergency save the fish operation.
There was a conference at my church, with the theme "fishers of men." The centerpiece of the conference was a kiddy pool with a bunch of small goldfish in it. At the end of the conference, they said anyone that wanted the fish could take them. A friend of mine took the two pretty ones, but then the teenage boys started daring each other to eat them! I saw one fish go down the hatch, and ran to get my mother to stop it. We ended up taking the entire batch home, with no fish tank! Every kind of large container was recruited to hold the fish until a tank could be set up. Had to do lots of water changes, found out local rainwater was VERY BAD for fish. (Luckily we only let Dad put the rainwater in one container, because none of the fish in that container made it.) In the end, I had about 10 survivors and a 10 gallon tank. I felt really bad for those fish, but stomach acid wouldn't have been pleasant to swim in either.