If there are 4 you can see there is a good chance there's another 10 you can't see
They lay eggs inside caves or under logs so you may not ever see them although they are large eggs and a nice orange colour. I hope you have some hardwood in the tank as it is a necessary factor to aid their digestion.
The male looks after the eggs and fry although the fry are pretty independent from the beginning.
At that size they could be 3 - 4 weeks old. They don't need special feeding as they will browse on algae and bottom feeder pellets. They also like veges - both fry and parents - like cooked peas (pop them out of their shell first though), zucchini, and cucumber. I believe they also like carrot and apple though haven't tried either myself.