Why would parents eat the fry after all they work they put into raising them?

[localfishbreeders]

My father in law used to breed discus about 5 years ago but he quit after most of his pairs would eat the fry. I'm not sure if he introduced new bloodlines or if he kept inbreeding them. He had all his water parameters in check. He kpet his pairs in 20 gallon tanks.

Any idea what would cause the parents to eat their fry? I'm thinking about giving it a go and see if I can grow a few. Found proven pairs for $300 is this usually a good investment?

[mmorris]

I'm guessing I answered this by email so we'll see what others think. $300 is OK generally but it depends on the pair. If you're not sure if they're nice and you can get pics you could post and see what people think. Other factors to consider is the age of the pair and the prior breeding history. Why is the seller selling them? Often it is because they are now past their prime, have very small batches or have a long history of egg or fry eating.