wild sailfin mollies, but the sail ain't there?

[Mako]

I finally found a tidal creek near my home in the lowcountry of SC, that is full of wild sailfin mollies (Poecilia latipinna). I came home with about 20 of them, and the males that I had are about 1.5 inches long, but have little female-looking dorsals. Have they not had time to develop, or do they sometimes do this in the wild? I know that the huge dorsal is NOT a mutation, it is their natural form (in males only).

[newaridiar]

I thought it was a matter of selective breeding (i.e. human intervention), of course I never really looked into it, just assumed. Maybe they just aren't sailfins.

[cdawson]

Most likely just aren't sailfins, you have pretty much every variety of molly down there in those tidal areas so there probably ARE sailfins in there.

[Mako]

Actually, cdawson, the only molly that is supposed to be around here is P. latipinna. The other mollies are Mexican and Central American. I can't tell by looking at the ones I collected that there is any degree of hybridization, they have a perfect P. latipinna coloring, but the males just have little dorsals. I suppose other molly varieties could have been introduced, but our winter water temp hits 50 or less for several months, I doubt any molly other than latipinna could handle that.

newaridiar--- Sailfins do develop (or at least do elsewhere than my creek!) the big male dorsals. In fact, they get bigger dorsals in the wild than in tank-bred specimens. You should see, in person, a full-grown natural male sailfin, quite a showoff! Sometimes you even run across a black-marbled molly in the wild. I just don't know if the ones I collected were too young, or if the swift creek flow is the culprit.

[Toirtis]

I agree with Mako...the wild/feral sailfins that we have around here all have the big dorsal (males).