Cacti sprouts stopped growing?

[Theo]

I've planted a cacti seed-mix 3 weeks ago, that started germinating after 1 week, but now it seems a bit like they have stopped growing?
Is there something I can do or is it normal?

Some fast and questions here:
- It's a mix, so I don't know what cacti it is
- I just used the soil that came with the mix, so I don't know what it's made os, should I change it?
- Should I use fertilizer?

Pics here:
[img]https://i44.tinypic.com/4jlvue.jpg[/img]

And next to a toothpick so you can see the size.
[img]https://i43.tinypic.com/2w68nyx.jpg[/img]

EDIT: both pics are sideways.

[Kisal]

Don't change anything yet. The babies are too small to move. Cacti grow slowly, so just give them the standard care you would provide for any cactus through the growing season. It doesn't matter that they are different species. That only matters because the seeds of some species sprout sooner than others. Once sprouted, the same care will do for all.

[Theo]

Don't change anything yet. The babies are too small to move. Cacti grow slowly, so just give them the standard care you would provide for any cactus through the growing season. It doesn't matter that they are different species. That only matters because the seeds of some species sprout sooner than others. Once sprouted, the same care will do for all.

Thank you so much Kisal! Finally an answer to my questions in here
I'm a bit nervous about the water, if I give them to less