Color in archerfish?

[fishtex]

I have had my 3 archers for just over a month. I know this is a little impatient, but when will color start to develop? They are between 3 and 4 inches. They are nice and healthy, extremely active. Most all pics I have seen of archers this size all have awesome yellow coloration on tail fin and other fins. They are eating hikari floating carnivore sticks, crickets and bloodworms. SG is around 1.005 for now.
Any reason why they don't have color?

Nice cell pic huh? - sorry no camera

 

[fishtex]

anyone?

 

[SalmonAfrica]

I can't remember, but when I kept two species of Archer together (T. jaculatrix and T. chatareus), only one of the species displayed the yellow colouration. The other, as far as I recall, doesn't develop this colour.