Age Matters
Too young — immature gonads produce low-quality eggs or sperm.
Too old — fertility drops, deformity rate rises.
Ideal breeding age: livebearers 3 to 18 months, egg-layers 6 to 36 months, cichlids 10 to 48 months.
Proven vs Unproven
A proven breeder (has spawned successfully before) saves months of trial.
An unproven fish of superior form may be worth the wait if your goal is line improvement.
Conformation Standards
Straight spine, even scale pattern, no missing rays or splits in fins.
Color intensity and pattern symmetry matter for ornamental species.
Temperament Compatibility
Overly aggressive males injure or kill females. Watch for body damage in first 48 hours.
Timid females fail to approach courtship displays. Consider a different female if no response by day 7.