I'm still learning & have a lot to learn, but it wasn't long ago at all that I had no clue about the importance of water chemistry or that new tanks need to cycle & how long that can take. I know Zebra Danios are considered to be fish that can make it through the cycle & survive, but my first aquarium was a MinI Bows 5 gallon & it had a Betta in there right from the get go. The first time I tested the water, it was nasty! Everything was high........especially nitrite & nitrate & the Betta was just fine. That fish could probably live in a septic tank. The Betta is stilll in there & doing just fine. Ofcourse, even that tank has good water now, but it sure didn't before....So correct me if I'm wrong, but I would suggest a Betta for a cycling tank.