Update:
Ponies are now three months old,and growing steadily.Larger ones reached 5cm (2")tall,while the smaller (few)are 3.5cm.Now 8 of them are yellow,the rest remain black.Still a herd of 234.
They are now taking whole frozen mysis well,they consume a 1"square in few minutes.They still take bbs.I´m glad I have frozen mysis,as my adult bs culture is in bad shape.I couldn´t have raised them all without it!