Swordtail "appendage"

[Fish Head J]

I am a new aquarium ownr so please excuse my ignorance with what may be a very stupid question but I have been unable to find an answer in any of the books. I have an male orange/black swordtail with a long appendage hanging from his underside. When I first noticed it yesterday it was about 1/4" long and I just assumed it was a stubborn piece of fish "waste" that would not let go. This evening however, it has grwon to more than an inch and shows no signs of detaching itself from the fish. What is this thing and should I be concerned and/or treating the fish?
Thanks,
FHJ

 

[Jchillin]

It's the gonopodium. It's quite natural, aids in reproducing.

 

[Skyrmir]

ROFL Jchillin

It is quite natural, it sounds like you just had a late developer. Usually the gonopodium grows about the same rate as the tail sword, sometimes it's late though.

Swordtail trivia stolen from badmanstropicalfish.com : An interesting fact on Swordtails is their ability to change sexes. All young swordtails are female and if a potential male starts to develop early, he will continue to become a slender small male. If a potential male goes through a female stage complete with the typical female form and gravid spot, he will develop into a large thickset "late" male.