[Cstar_BC]

I'm not sure whether he/she is fat or full of eggs - but there's two fat ones and one small one so I assume 1 male 2 females

 

[Cstar_BC]

Pic of Cory and baby pleco

 

[VElderton]

It's hard to see your fish at the photo resolution you used - often thumbnails are like that.

 

[SeaHorse_Fanatic]

Looks like a preggie female cory to me.

 

[Rjjm]

In most cories, males are slender and longer with more pointier snout while female are rounder specially around the belly area and around the head.

 

[Cstar_BC]

I've never seen her do any mating behavior . I guess the male may not be mature enough - or I simply don't have enough males

 

[mollyb]

give them a water change (25 %) with cooler (5 degree) water and watch! I agree, female full of eggs.

 

[Mick2016]

I bought two Julii Corys at the same time from the same tank/seller. They were identical in size and shape. However, 6 months later, the smaller/slimmer one is clearly a male while the other one - twice the size of the first - is a female. And they are inseparable (although I do not expect to see any offspring.)