Question: Different lengths.... same batch¿

In the beginning of this year Frangipane (lol) laid about 300 eggs and 60 of them hatched.
Now I guess there are about... 50 left (some of them are eaten, probably....).

I feed them daily, do water changes a few times a week (sometimes I forget to do it and then it's once a week)...

I have them in 3 tubs...
But their sizes are so different... Now I know that they don't grow at the same rate (and that the first batch isn't always the best...)... but I'm a little worried about most of them.
6 of the axies are now about 4 - 4,5 cm... the rest of them are 1,5 - 2 cm.

I fed them BBS and I still give it to them as a 'snack' and I try to feed them chopped bloodworms or tubifex but it looks like they still can't handle it (the big ones can...) and that some of them still have 'empty bellies'. When it just don't work I feed them BBS again...
They also don't seem to grow... They all have front legs (some have buds as back legs, but the bigger ones are 'complete axies') but... they don't grow...

I also 'breed' some red wigglers and sometimes I find a tiny one that I can feed my babies... at least... that's what I think. They still don't eat it.
It's not that they don't eat at all.... they eat the BBS.

What can I do to... make them grow faster... or... just make them grow...?

it´s not unusual, that a batch is growing differently. You should separate them by size and feed them adaquately for that the big ones won´t eat the little. You can feed the bigger bloodworms and the smaller BBS and daphnia. You can also try blackworms.
Keep the water at 20-21 degrees C and clean; that´s all you can do.

Tina