Table 2.

Different stages of embryonic development of stinging catfish in different time period.

Figure No.	Development Stages	Size in Diameter (μm)	Development Time Range in Both System (Hour: Minutes)	Characteristics
A	Fertilized egg	1355.06 ± 17.15	00:00	Round, transparent and adhesive in nature.
B	Blastodisc formation	1364.88 ± 28.43	00:20–00:25	Cytoplasm accumulated at the anterior part to form animal pole or blastodisc where cell divisions occur. Reddish blastodisc on the pole of fertilized eggs were easily identified with the naked eye.
C	2-cell	1438.09 ± 25.29	00:30–00:35	Two cells over the yolk sphere were clearly visible at the first cleavage stage.
D	4-cell	1440.59 ± 47.69	00:40–00:50	Four cells at the animal pole produced by second cleavage.
E	8-cell	1457.19 ± 9.92	1:00–1:10	Third cleavage produced eight cells arranged in two rows of four cells where little overlapping of blastomeres was observed.
F	16-cell	1472.02 ± 13.17	1:20–1:30	Sixteen cells were produced in fourth cleavage. At this stage cell counting becomes difficult and cell size becomes reduced due to successive cell division.
G	32-cell	1472.16 ± 23.46	2:00–2:20	Fifth cleavage where the blastomeres were visible in 2-3 layers producing 32 cells.
H	64-cell	1475.81 ± 19.64	2:30–2:40	Sixth cleavage where overlapping of blastomeres was observed producing 64 cells and were placed in 2–3 layers.
I	Morula	1480.44 ± 30.88	2:50–3:00	Repeated cell divisions leading to the formation of multicellular blastodisc where the cells were very small and gave a flowery look at the animal pole.
J	Blastula	1486.01 ± 1.22	4:00–4:15	Epiboly formed as embryonic shield on the animal pole and blastoderm was compressed occupying more than half of the area over the yolk sphere.
K	Gastrula	1491.03 ± 30.56	6:35–6:40	Germinal ring was formed with two somites where thick layer of blastoderm occupied 3/4 area over the yolk sphere. The broader end became the future cephalic part of the embryo.
L	Somatic formation	1509.26 ± 40.58	9:00–18:00	Antero-posterior axis become distinguishable, cephalic portion become broader, and embryonic rudiment became distinct with two somites. Further development of somites reached 22–25, and the yolk became completely encircled by kidney shaped embryo with clear distinction of head and tail.
M	Yolk plug	1523.80 ± 31.66	19:00–19:30	Yolk plugs are the remaining patch of endodermal cells formed and exposed on the vegetal surface of the blastula.
N	Twisting movement	1551.90 ± 23.59	20:00–21:00	Tail became free from yolk sphere and frequent embryonic twitching movements occurred as the embryo tried to rupture the perivitelline membrane.
O	Pre-hatching	1647.44 ± 40.61	21:00–22:00	Wriggling movement increased as chorion wall still enclosed the embryo, heartbeat increased to 68 times per minute.
P	Newly hatched larvae	2780.08 ± 43.67	22:30–23:00	The egg membrane was broken down and the embryo tail first emerged, followed by the trunk and head region. It took around 2 h for completion of the hatching from twisting movement of the embryo.