is it dominance or age

[sun catfish]

i have 4 edlers livebearers and 1 of the males has i bright yellow top on his tail fin that changes to a pitch black when he eats or shows of to the females but the other male has no color on his tailfin other then the common orange spot on the base of the tail. is this dominance or age or just the way the color was bred into the fish?

thanks i dont think they are sick just interested in the habit of them.

 

[joe jaskot]

The color of your fish is from the way it was bred, not dominance or age. There are many different types and colors of endlers livebearers depending upon collection locations. There are also many hybrids around resulting from crosses of endlers and guppies.