I have just recently purchaced 3 yellow labs that are now in the 30G QT before adding them to the 75G male peacock tank in a few weeks. These are my first experience with yellow labs and to me they look more golden yellow than the intense bright yellow I often see in photos! They are 1-1 1/2" long and have a thin black line on the dorsal fin, though not a really dramatic line. Are they probably mixed or is it common for them to have this coloration when yound and change as they get older?