This pair you'll have to seperate after breeding.
Generally they are awesome parents. but a couple things could of happened.
If mom or dad think the other parent is hurting the fry they will attack each other. Something sucking a fry into thier mouth clean it turns into a battle between mom and dad. Dad could of thought mom was eating the fry.
The other thing, if the convict thought there was a threat, net, hand, cat watching through the glass, tv too loud by the tank, ect. . . . . . . . then they are apt to eat thier own fry. That way the predator gets no meal, and they can re use the energy to produce another batch. If one parent thinks there is a threat, and the other doesn't they will battle over the saftey of the fry.
Possibly dad wanted to breed again, and mom didn't. That will cause a fight, and the male to kill the fry to try and get the female to breed again. These personalities have to be seperated from thier fry.
And occasionally you get a bad parent. This is the first time I've seen this happen with convicts. I have seen them attack fry after they get bigger, and they see them as a threat to thier mate/territory.
Glad mom was ok.