I had 3 at the time and one died or got eaten, but now I'm left with a pair. And yes, they differ in size. Female is the larger of the two. My female's body size is almost twice as big as the male. The eggs are hardly visible. You will just need to monitor the abdomen part. Once you see it bulge in size, then chances are the female is carrying eggs. I have yet to have the time to attempt to raise the fry. Good luck with pairing them.