I believe they give live birth, the females will carry the brood until they are a little bigger, then release them. You can keep blue and red together just fine if you are not worried about or trying to have them reproduce in your tank as the babies will be regular cherries. They are estimating the added bioload to any tank, with other fish or without. So if you had 10 shrimp in a tank, it would account for a gallon of the water in that tank.