sail fin tetras revisited

[Magnum Man]

so, I have 5 that have settled into my tank... maybe all females??? 3 of them in this 1st picture, and 2 others that have claimed caves... not sure if that is a male only trait, or if an alpha female will claim a cave??? 2nd picture is my biggest, and food drifts into the cave, so it has little interest in leaving, and is only visible with flashlight assistance... it seems to have a colored ribbon, along the top of it's dorsal, so likely a male???

 

[Back in the fold]

This is the Crenuchus spilurus ? Dr. Innes , in his classic “ Exotic Aquarium Fishes “ , states that a change occurs in the males at about two to three years of age . When the male passes the 2 1/2 inch length , his dorsal and anal fins , which previously had been only a little fuller than on the average fish , suddenly sprout into luxurious elegance , so that he is scarcely recognizable as the same individual . There are no distinctive colorings aside from the long black dot at the tail base .

 

[Mr Limpet]

The fish in the cave, judging by the shape of the dorsal fin, might possibly be a male, although female Crenuchus also claim caves. My male grew from a 3/4 inch baby into a 3 inch beast in about a year.