Corydoras, when breeding tend to dart about alot and become much more active than usual. It's only fair a tank that is big enough for a group of corydoras to swim around happily is given. My tank is 3ft long. That's plenty small enough in my opinion. Te water stays more stable, which means they are more likely to be happy and breed. Don't try and move breeding corys. I've tried this and once moved the corys stop the breeding and resume normal behavior. Eggs get layed on glass or plants, in 4 years mine have never layed on wood or rocks.
Egg rates are varied, last month my adolfi, Sterbai and pandas all layed, but the similies are holding back. For example the adolfi females layed around 30 eggs all together in December, this month only 6 days have passed and they have layed 20 already. Good foods allow them to 'cook up' good sized eggs and good numbers. In my experience the males get very wound up, and the females struggle to get a chance to lay. Lots of cover and tank space is therefor nesassary for the females to get some rest.
Cheers
