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
Cleavage (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
Blastula (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
Gastrula (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
Segmentation (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
Pharyngula (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
Hatching (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.