question on sexing. do the females have any color at all or are they compleatly silver? reason being i have a large one about 7" and all it has is some red on the top of its dorsal fin. or maby he is just a late bloomer
Likely a female...but could be wrong. I have a male that is about 9" that lost all coloration about a year ago when he was "punked out" in the tank. I've had this happen with other males of other species often. I have a F. rostratus that will color up the day I pull the dominant male out and lose his coloration within an hour of me putting the dominant male back in If your fish is not stressed by anything and is likely (because of size/tankmates) to be the dominant fish, then you probably have a female. Males also tend to have higher bodies. Really old females of most species often take on male colorations. It's kinda like menopause for fish . You should be able to vent the fish at that size, but it's kinda a learned skill.
I've got a trio of d. comps about 5.5" in length. I suspect I have two males and a female (the suspected males have reddish dorsal and anal fins, while the presumed females fins lack coloration). The two with the reddish fins occasionally take on a temporary blue-silver sheen when excited.
I believe because I have more dominant haps in the tank the mature coloration of the 'males' is being delayed.