I've bred cherry barbs in the past. The bright red is the male and the brownish one is the female. You'll have more luck if they are in a group, but you might get those two to breed. Throw in a lot of floating plants and condition them with brine shrimp and bloodworms. They will move about through the plants side by side scattering the eggs as they do a little dance and shake their way through. If you don't have plants, they, or the group, will eat the eggs as they are scattered. The eggs have microscopic hooks that hook onto the plants. There is no parental care involved, obviously. A pregnant female will be filled with roe, and thus will have an extended belly. The male's color is pronounced when in breeding condition.