At what age can Psuedomugils breed?

[ScareCrow]

Bit of a long shot but does anyone know at what age Psuedomugils (ideally luminatus) can breed?
I have a group of six week old fry growing out in a tank and have just noticed some much younger (probably week old) fry in with them. My adult Psuedomugils haven't been in there for 10 weeks or more.
I know the eggs can take a long time to hatch but I'd heard up to 18 days not 5-6 weeks. I can't believe that 6 week old fry are able to breed yet, though they are sexable.

Here's a pic to roughly show the size difference. Juvenile fry in bottom right is about 10mm. Fry top left circled is a probably 4mm.

 

[Konsa]

Hi
Have you moved any plants between the tanks.
I had babies appearing in new tanks with just plants in.
Regards Konstantin

 

[ScareCrow]

Hi
Have you moved any plants between the tanks.
I had babies appearing in new tanks with just plants in.
Regards Konstantin

Thanks for your reply, sorry I didn't see it. I seem to be getting notifications sporadically.

I've only moved plants from the tank containing the fry to my other tank so I don't think they've made it in on plants.