I have an established 10 gallon tank with 5 zebra danios and 5 neon tetras in it. I'm in the process of doing a fishless cycle on a new 20 gallon tank. Once the 20 cycles, I'm planning on moving the tetras and danios into it, and putting guppies in the 10 gallon. I'll gradually add some more neons and cory catfish to the 20 gallon.

Anyway, my question is about the best way to do the transfer of the neons and danios. I was thinking I could move the danios to the 20 first, leave everything to adjust for a week or two, then move the neons. Then the same day I move the neons, I would put guppies in the 10. That way no tank would go without fish to feed its cycle.

My other thought was that I could move all the danios and tetras to the 20 all at once, and put guppies in the 10 that same day. The problem with that is that it might shock the cycle of the 20 gallon, going from no fish to 10 fish.

Your thoughts?

Always better to go slow when moving fish into a new tank. The cycle will have to adjust with the bio load in the tank. So your right in thinking on going slow with them. Neons are specially sensitive to change