Breeders are rounded guppies with physically female traits. In Adventure Mode, they appear in Tank 4. They are colored similarly to regular guppies and have a larger, round abdomen. There are three stages of growth from baby to medium to adult. Unlike most fish, they do not drop money but instead give birth to baby guppies.
These fish always overpopulate the player's tank because they continue to produce baby guppies regardless of the player's choice. It's recommended to have a balanced amount of breeders to carnivores in order to gain a profit in the form of diamonds while keeping the guppy population under control. Amp can also be used to obtain a large amount of diamonds for a large profit that can easily be used to buy more fish.
It is not recommended wasting a pet slot in Tank 4 on Prego because of the excessive birthing done by breeders.
In Virtual Tank, when a breeder has become an adult, the first guppy it gives birth to will be named after the breeder. (Example: if the breeder is named "Momma", then the baby guppy's name will be "Momma JR."). All other baby guppies the breeder gives birth to after its first can be eaten by carnivores and guppycrunchers.
The JR. fish drops gold shells as a baby, blue conch shells when medium, spiral shells as an adult, and bags o' shells as king guppies. It shares the price (used to calculate resale value) of the breeder. It will have the same likes as the breeder it came from and it's home town will be "Virtual Tank". Instead of a purchase date it will have a birth date.
- There are many differences from a breeder and Prego
- The breeder swims faster as it gives birth and needs to eat
- Prego makes a fart sound when she produces a baby guppy, but a breeder makes a "pop"
- But a breeder makes a fart sound when she produces a Jr. Guppy in Virtual Tank.
- A breeder has a fin on it's back, but Prego doesn't
- Prego is always large, but a breeder can be small, medium, or large
- Prego wears a blue scarf with white polka-dots, whereas breeders do not
- Prego is invincible, but breeders can die and need to be fed (like guppies)
- Prego shows when she is going to produce a baby, but breeders don't
- Prego can be used in tanks other than Tank 4, but breeders are confined to Tank 4
- It is the only fish that produces other fish.
- Breeders, along with starcatchers, produce the highest pitched death sounds.