Breeding variatus platy, but no male fry?

[Day By Day Aquariums]

I have some redtail blue variatus platy. I’ve had them for quite a while, and have dozens of fry, most of which are sexually mature. Not a single male. Any thoughts to why?

[nabokovfan87]

There is an assumption that temperature plays a role.

What size are the fish?

Certain males can present as female for many months longer.  I'm not sure why, but it seems to be common. I wouldn't expect 100% of the males in a batch to do so, but just something to note.

[Day By Day Aquariums]

On 7/17/2023 at 3:01 AM, nabokovfan87 said:

There is an assumption that temperature plays a role.

What size are the fish?

Certain males can present as female for many months longer.  I'm not sure why, but it seems to be common. I wouldn't expect 100% of the males in a batch to do so, but just something to note.

Some of the fry are almost 8 months old. Fully grown, the females already are starting to have fry of their own. I’m aware males can look female for quite a while, but for not a single male I feel is odd. I know temperature plays a role. But I breed quite a lot of live bearers and other fish in a controlled fish room. My other variatus platy have a mix of male and female fry. But the redtail blue line has only been female so far, and it’s the oldest of the lines of platy I have. 

[PineSong]

I agree with you that eight months is much longer than expected for the males to show themselves. I did recently have a sword tail begin to develop an gonopodium at around the eight month mark. and in the past I had a platy that was at least that old if not older start to Change. So I wouldn’t rule it out completely yet, although I do not know what factors might make them so late to develop.