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Zebrafish Embryo Staging Calculator

Convert hours post-fertilization and incubation temperature to developmental stage using the Kimmel et al. (1995) staging series. Automatic temperature correction for 20–33°C.

ZebrafishEmbryologyClient-Side
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Load example Embryo Staging data to see the full workflow

Configuration

20°C28.5°C33°C
  • Determining the developmental stage of embryos incubated at non-standard temperatures
  • Planning collection times for target stages (e.g., scheduling a 10-somite collection)
  • Estimating time until next developmental milestone for imaging or fixation
  • Converting between actual elapsed hours and standard hpf for publications

Don't use for

  • As a substitute for morphological confirmation — always verify stage under a microscope
  • For mutant or transgenic lines with known developmental delays — timing may differ
  • For temperatures outside 20–33°C — embryos are not viable in this range

Kimmel Staging Series Overview

The zebrafish staging series by Kimmel, Ballard, Kimmel, Ullmann, and Schilling (1995) defines the canonical stages of *Danio rerio* embryonic development from fertilization through early larval life. The series divides development into major periods:

  • Zygote (0–0.75 hpf): Single-cell stage with cytoplasmic streaming
  • Cleavage (0.75–2.25 hpf): Rapid synchronous cell divisions (2-cell through 64-cell)
  • Blastula (2.25–5.25 hpf): Cell cycles lengthen, MBT begins, epiboly initiates
  • Gastrula (5.25–10 hpf): Epiboly completes, germ layers form, embryonic axis established
  • Segmentation (10–24 hpf): Somites form (~2/hour), organogenesis begins
  • Pharyngula (24–48 hpf): Heartbeat, pigmentation, pharyngeal arches
  • Hatching (48–72 hpf): Embryos hatch from chorion, pectoral fins elongate
  • Larval (72+ hpf): Free-swimming, feeding, swim bladder inflation

All stage timings are defined at the standard incubation temperature of 28.5°C.

Temperature Effects on Zebrafish Development

Zebrafish are ectotherms and their developmental rate is directly governed by ambient temperature. The viable range for embryonic development is approximately 20–33°C, with the standard being 28.5°C.

Key effects of temperature manipulation: - Cooler (20–25°C): Development slows to 28–60% of standard rate. Useful for slowing development to collect stages at convenient times (e.g., overnight incubation at 22°C to obtain late-gastrula embryos in the morning). - Standard (28.5°C): Rate factor = 1.0. All published stage timings apply directly. - Warmer (29–33°C): Development accelerates to 105–132% of standard rate. Temperatures above 33°C cause developmental abnormalities and lethality.
Important: Temperature shifts should be gradual (≤2°C/hour) to avoid thermal shock. Prolonged incubation outside 25–30°C may affect morphology and gene expression patterns independently of staging.

Frequently Asked Questions

Next Steps

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