i just got a pare of kribensis and at first the females belly was more a pale color and now it's more red or purple and a little bit bigger. yes i know they can't get pregnant because they lay eggs but i just don't know what else to call it.
The term is 'gravid' I believe. Females definately do get quite round with eggs when they're ready to lay. Have you seen much courting behaviour (fin flaring, strong colours, female bendin body in half and showing her belly to the male to make it look really big?). After a few spawns it becomes really easy to pick the signs.