Looking fantastic Eriik...they really are!
Not be long before you get some pups.
Mine are doing ok thanks.
I had 3 stunning little pups a few months ago from one pair but these were born on 89 days!!...can't get away with that with Hystrix, they are generally slow developers 150 days being more typical a gestation period. I do have pics of them but it hurts to look at them. They were almost there, in some of the pics they look fully developed but all arrived with a fairly large yolk sac and although I kept them on a glass bottom to prevent the sac from puncturing it proved not to be enough, I lost all 3 one day after the other....very sad!
On a brighter not I think one of my other females is gravid, its a pair I keep on there own with some mixed community sp similar to your set up Eriik, these are various disc Characins of the genus Myleus, in with these are a few Geophagus sp.....just love the Amazonian theme.
Anyway enough about me.
I wish you all the success in the world with breeding these special little rays.