The Breeder is a fish related to Prego. It eats regular fish food like a Guppy. In Adventure Mode, you will start with one Breeder in Tank 4 and a new one can be bought for $200. When the Breeder becomes medium-sized, it will start giving birth to Guppies. In Virtual Tank, sometimes there will be a Breeder on sale for 5000 shells. The Breeder can only give birth when full-sized this time, and will give a free Guppy (it is named after the Breeder, but with "JR." at the end) with the same traits (example: musical breeder will give a musical guppy), as long as you have space. She will not give birth to more guppies until she gives out the free one.