Please stop keeping betta fish in small, unfiltered cups, as this is cruel to the fish. A single male betta fish should be kept in at least one-gallon of clean, filtered water. Female betta fish can be kept with other female betta fish and certain other species of fish, though should not be kept in a small, dirty cup and should, like males, be kept in a filtered tank. Lying to your customers about the proper keeping of bettas is not a healthy business practice, for it is deceitful to your loyal customers.