Hi Andrzej,
I’m sorry this reply is so late, but perhaps it will still be helpful. I hope your fry are thriving.
If you want to grow your own live food, you may find these links useful (one is Polish 😆 ) :
http://faq.thekrib.com/live-food.html
http://www.ichthyotrophic.pl/live_en.html
You can order live food here in Holland online. Just google “levend aquarium voer” for lots of choice.
Best wishes,
Jonette