Guppy Gender...

[Major Risk]

Usually, I can easily sex guppies. However, this guppy is a pain as it has a Male anal fin, but it has a Gravid spot too. I have heard that sometimes in early development guppies can change gender, do you think this is what has happened?
I have a few pictures but they are really bad quality so are of no use really. (It is the guppy that seems "Golden" that is the guppy in question. The adolescent guppy.) You can only see the gravid spot...but not the gonopodium (which is there).
This is really annoying for my population control, as I am having to section off the Males and Females to two separate tanks...
Btw all the offspring turn out colourless now, it seems this is due to a reduced gene pool... as I have checked for a Mosquito fish and there are none.
Thanks in advance for advice.

 

[BlaseMrNiceguy]

The only time they will really change gender is if its all one sex. Say you have all females one may turn into a male so they can keep the family going, and vice versa. My guess is if you see a gonopodium it's probably a male. But to be safe I would leave him in general population until you see him start to flex his gonopodium as that is generally a sign they are beginning to sexually mature.

 

[Major Risk]

Ok, thanks I think he was a female then but has changed into a male. I suppose it is better getting 1 female pregnant if I put him in the male tank and he turns out to be a female then to put him in the female tank and get all the females pregnant..if he's a male.

Thanks a lot!