Dominant and Recessive Basics
Each fish carries two copies of every gene. Dominant traits show if even one copy is present. Recessive traits require both copies.
Many color morphs (albino, lutino, double tail) are recessive. Two visible-trait parents produce 100% visible-trait offspring, but one visible parent crossed to a non-expressed carrier yields 50%.
Inbreeding Coefficient
The coefficient measures shared DNA between breeding partners. Siblings share 50%, parent-offspring 50%, cousins 12.5%.
Coefficient above 25% increases risk of deformity, reduced fertility, and shortened lifespan in offspring.
Safe Line-Breeding Patterns
Rotate between two or three unrelated lines to keep coefficient low.
Outcross every 4 generations to an unrelated bloodline to refresh vigor.
Record Keeping
Keep a pedigree for every fish. Note parents, spawn date, notable traits, and health issues.
Without records, inbreeding coefficients become guesswork after 3 generations.