This material is from the 4th edition of The Zebrafish Book. The 5th edition is available in print and within the ZFIN Protocol Wiki.

Zebrafish Developmental Staging Series

Embryonic stages are modified from Kimmel et al., 1995. Developmental Dynamics 203:253-310. Copyright ©1995 Wiley-Liss, Inc. Reprinted only by permission of Wiley-Liss, a subsidiary of John Wiley & Sons, Inc.

Select a stage name below to get a detailed description and images. You can also browse the zebrafish Anatomical Ontology (AO) to show anatomical terms that are present at that stage.

(h = hours of development at 28.5°C)

Period Stage Begins Developmental Landmarks Anatomy
Zygote (0 - 0.75 h) 1-cell 0.00 h Cytoplasm streams toward animal pole to form blastodisc Browse AO
(0.75 - 2.25 h)
2-cell 0.75 h Partial cleavage Browse AO
4-cell 1.00 h 2 X 2 array of blastomeres Browse AO
8-cell 1.25 h 2 X 4 array of blastomeres Browse AO
16-cell 1.50 h 4 X 4 array of blastomeres Browse AO
32-cell 1.75 h 4 X 8 array of blastomeres Browse AO
64-cell 2.00 h 3 regular tiers of blastomeres Browse AO
(2.25 - 5.25 h)
128-cell 2.25 h 5 blastomere tiers; cleavage planes irregular Browse AO
256-cell 2.50 h 7 blastomere tiers Browse AO
512-cell 2.75 h 9 blastomere tiers; YSL forms Browse AO
1k-cell 3.00 h 11 blastomere tiers; single row of YSL nuclei; asynchronous cell cycle Browse AO
High 3.33 h > 11 blastomere tiers; blastodisc flattening begins; YSL nuclei in two rows Browse AO
Oblong 3.66 h Blastodisc flattening; multiple rows of YSL nuclei Browse AO
Sphere 4.00 h Spherical shape; flat border between blastodisc and yolk Browse AO
Dome 4.33 h Yolk cell bulging toward animal pole as epiboly begins Browse AO
30%-epiboly 4.66 h Blastoderm an inverted cup of uniform thickness Browse AO
(5.25 - 10.33 h)
50%-epiboly 5.25 h Blastoderm remains of uniform thickness Browse AO
Germ-ring 5.66 h Germ ring visible from animal pole; 50%-epiboly Browse AO
Shield 6.00 h Embryonic shield visible from animal pole; 50%-epiboly Browse AO
75%-epiboly 8.00 h Dorsal side distinctly thicker; epiblast, hypoblast, evacuation zone visible Browse AO
90%-epiboly 9.00 h Axis and neural plate; brain and notochord rudiments Browse AO
Bud 10.00 h Tail bud prominent; early polster; 100%-epiboly Browse AO
(10.33 - 24 h)
1-4 somites 10.33 h First somite furrow Browse AO
5-9 somites 11.66 h Polster prominent; optic vesicle, Kupffer's vesicle, neural keel Browse AO
10-13 somites 14 h Pronephros forms Browse AO
14-19 somites 16 h EL (embryo length) = 0.9 mm; otic placode, brain neuromeres Browse AO
20-25 somites 19 h EL = 1.4 mm; lens, otic vesicle, hindbrain neuromeres Browse AO
26+ somites 22 h EL = 1.6 mm; blood islands, otoliths, midbrain-hindbrain boundary Browse AO
(24 - 48 h)
Prim-5 24 h EL = 1.9 mm; early pigmentation, heartbeat Browse AO
Prim-15 30 h EL = 2.5 mm; early touch reflex, retina pigmented Browse AO
Prim-25 36 h EL = 2.7 mm; early motility, tail pigmentation Browse AO
High-pec 42 h EL = 2.9 mm; rudiments of pectoral fins Browse AO
(48 - 72 h)
Long-pec 48 h EL = 3.1 mm; elongated pectoral fin buds Browse AO
Pec-fin 60 h EL = 3.3 mm; pectoral fin blades Browse AO
Larval Protruding-mouth 72 h 3.5 mm total body length Browse AO
Day 4 96 h 3.7 mm total body length Browse AO
Day 5 120 h 3.9 mm total body length; 6 teeth Browse AO
Day 6 144 h 4.2 mm total body length Browse AO
Days 7-13 168 h 4.5 mm total body length; 8 teeth Browse AO
Days 14-20 14 d 6.2 mm total body length; 10 teeth Browse AO
Days 21-29 21 d 7.8 mm total body length Browse AO
Juvenile Days 30-44 30 d 10 mm total body length; adult fins/pigment Browse AO
Days 45-89 45 d 14 mm total body length; 12 teeth Browse AO
Adult (90 d - 2 y)   90 d Breeding adult Browse AO
Unknown Stage yet to be determined.