Zebrafish Survival Curves in the Laboratory
Zebrafish attrition follows a predictable pattern under standard laboratory conditions. The steepest losses occur during early development:
Critical loss points:
- 0–1 dpf: ~5% loss from unfertilized eggs missed during sorting and early developmental arrest
- 1–3 dpf: ~5% loss from gastrulation/segmentation failures and morphological abnormalities
- 3–5 dpf: ~5% loss around swim bladder inflation — larvae that fail to inflate cannot feed effectively
- 5–7 dpf: ~5% loss at the "point of no return" where yolk reserves are exhausted and larvae must actively feed
- 7–14 dpf: ~5% loss during the transition to external feeding and early juvenile growth
These rates assume wild-type fish under optimal conditions. Mutant lines, suboptimal water quality, or crowding can double or triple these losses at each stage. Always calibrate with your own colony data when available.
Experimental Design for Larvae Assays
Most zebrafish larvae experiments use multiwell plate formats:
- 24-well plates: 1 larva per well, behavioral tracking with larger arena, preferred for complex locomotor assays
- 48-well plates: Higher throughput, adequate for basic activity monitoring
- 96-well plates: Standard format for drug screens and high-throughput phenotyping at 5 dpf
- 384-well plates: Emerging format for ultra-high-throughput chemical screens
Key planning considerations:
- Plate format determines your target N (must fill complete plates for balanced experimental design)
- Include untreated and vehicle controls — typically 1 control column per treatment plate
- Larvae should be size-matched and morphologically normal at plating
- Plan to collect 2–3× more larvae than plate capacity to allow selection of healthy, staged animals
- Stagger egg collections across consecutive days to ensure adequate numbers despite daily variability
