Why Culling Matters
Deformed fry rarely thrive and often pass defects if they reach breeding age. Selling or giving away deformed fry ruins your reputation and spreads bad genetics.
Culling early (before visible suffering) is more ethical than raising fry that will later suffer organ failure or cannot swim properly.
Common Deformities
Bent spines (scoliosis) — visible from 2 weeks. Swimming sideways or in circles indicates progression.
Short gill covers exposing gill filaments — typically fatal by 8 weeks.
Missing ventral fins or cloaca — incompatible with long life.
Ethical Methods
Clove oil is the most humane option. Mix 5 drops in 100ml tank water, add fry. Loss of consciousness occurs within 30 seconds, death within 3 minutes.
Never use sudden temperature changes, bleach, or flushing down drains — these cause prolonged suffering.
Stock Quality Improvement
Culling 30 to 50% of each spawn for form, color, and vigor concentrates genetics in the remaining stock.
Keep detailed logs of which pairs produce low cull rates — those are your core breeding stock.