I'm going to put this into the "what's done is done" category, but the idea of using a fish to cycle a tank is a tad archaic, that fish will go through an ammonia spike that while probably not fatal may not be the most pleasant thing for the fish.
That said, what was unsuccessful about your prior tries? Why did they fail? Did you do something differently each try or just did the exact same thing?
Awesome! Thanks for thatWelcome to BAR. Lots of resources here. Check out other people's tank journals because we all started from scratch. I hope you find this hobby rewarding and spend the time it is needed to be successful.