Young Molly - Changing Sex?

[LauraFrog]

I bought them a few weeks ago, along with three platies. The black female (not a standard black molly, more iron grey than black and diff shape) is fine, but the yellow one is changing. Anal fin is thinning out and lengthening, 'she' is growing and chasing the female all the time, poking at her underside. I've heard that the male sex organs are the last things to develop in male livebearers - could 'she' be a juvenile male? I'm lucky that I know somebody who will take the fish because I can't keep a male and a female without any other mollies in a 20L tank, that would be silly and cruel in my opinion.

Please help.

 

[lilfishie]

sounds like a young male, mollies take over a year to be noticeably sexable sometimes

 

[theotheragentm]

Mollies CAN NOT change sex. What happens is that developing males may be suppressed when in the presence of a mature male. You probably got a male that is just expressing his maleness finally.

 

[LauraFrog]

Changing sex was an error of communication on my part - more making it obvious that I was wrong when I sexed it! When I bought it there was no gonopodium, but that's developing and the fish is getting bigger too - if it gets any bigger, I won't be able to keep it anyway because my tank is very small and I don't want my fish to be cramped.
It bit off part of the male platy's top fin this morning. It's twice the size of the platy. I've made arrangements with the person who can take it because if this keeps up it will kill the male platy and drive the female molly insane.

Poor Pointer. I didn't want this to happen to - him. I keep writing her, because I thought Pointer was female for so long. At least he'll have a good home where he's going.

Thanks for the help.