Do you mean a month's time between the top two and bottom photo?.....incredible growth if so...what is your feeding and water change regimen?
Yeah,I guesstimated them to be around six to eight inches in length and you've certainly done well with them.They might spangle up and turn out to be kelberi,everything else about their looks indicate to me that they are but if they turn out to be some sort of hybrid they still look impressive.
Four times a day..now that's what I call power feeding.
So are those dats eating anything else besides shrimp?