Why are my zebra and pearl danios all staying at the bottom of the tank?

Question

I've had them for over a week and this is the first tie they've done this. They are all going to the corners of the tank and hiding.

Why are they doing this?

Answer 1

They're scared but they will soon go to the top to feed. It happend with my sisters fish but there dead please help!

Answer 2

Test the water quality. As soon as fish show erratic behaviour, suspect there's water problems. With being there a week they are due their partial water change, do that and see if it helps.