Zebra danio help?

[Benfish1198]

Hey, I just started up a new 40 gallon tank so after setting it up I decided to brake it in. So I proceeded to go to petsmart and pick up 3 zebra danios. Ive had them for a day and 2 are doing perfectly fine and one is hanging around the bottom but if I go away he will stop hiding under some of the decor. He will come up for feeding sometimes I would like to know your oppion on this?

 

[Khuligirl93]

I just learned about cycling but I already have fish. What now?! - Aquarium Advice
By "break in" I assume you mean cycle?
You might be experiencing an ammonia spike, which could cause your fish to show stress.
You will need an API freshwater master test kit to test the ammonia, nitrite, and nitrate levels of your tank, and you will need to do frequent water changes to protect your fish.

 

[Benfish1198]

steps ahead I did purchase that I have zero nitrates or nitrites and 25 ppm ish of ammonia