Hi,
in the section below AAA Mm vs Blackrays i posted pictures of my parents and pups,those pups are approx 8 months old,its not till now i can see significent changes,i took those shots only last week,now they have changed again,the marbling is coming through and the rings around the spots are becoming darker and thicker.Ive seen wild Marbles at 30cm discs that havent finished developing their patterns,i believe foods such as Hikari massivore (fantastic food)which contain all the ingredients for healthy development may speed the process up in captive rays,mine do great on it though i do feed lots of earth worms,prawns,mussels etc.