Male typically needs to be bigger, but I've seen it both ways. They need to be close in size. 1-2 inches difference is good. I will tell you from experience it is much easier to breed larger and more mature males. Younger males just don't seem to get what you are trying to accomplish. Any can be bred with any, but typically if you breed an EBJD female with a normal male, the eggs don't turn out. That's my experience. I know people who have successfully done it. The female above was about 7 inches long and laid eggs three times. The normal Jack attempted to fertilize, but the hatch was unsuccessful. Male EBJD to normal female, I'm 2 for 2 so far. Larger tank is preferred with lots of vertical and slanted vertical rocks. They will not lay on flat surface but on inverted rocks and cave sides.