EMBRYONIC DEVELOPMENT:

The embryonic development of the Mirror carp was divided into six periods: zygote, cleavage, blastula, gastrula, segmentation, and pharyngula period. Each and Every steps were distinguished from other.

UNFERTILIZED AND FERTILIZED EGGS OR ZYGOTE:

• The unfertilized eggs of Cyprinuscarpio var. specularis were spherical in shape.

• Eggs were yellowish white in color. The eggs were adhesive in nature.

• Unfertilized eggs ranged between 1.05-1.06mm in diameter.

• Fertilization of eggs took place as soon as the sperm enters into the eggs. The fertilized eggs were adhesive, demersal and round in nature. The eggs deposited singly and were highly adhesive throughout the incubation period. These became translucent as development progressed.

• The diameter of the fertilized egg capsule ranged between 1.08-1.11mm. 30 minold egg was yellowish white and diameter ranged between 1.41- 1.42mm.

CLEAVAGE:

• The first cleavage that divided the blastodisc into two blastomeresor 2 distinct equal size cells was observed at 45 min of post-fertilization.

• The second cleavage completed (4-celled stage) at 60min after fertilization where the blastodisc was divided into 4 distinct cells.

• 8-celled stage occurred at 90 minutes after fertilization followed by 16-celled stage at 2h after fertilization.

• 64-celled stage was occurred at 3h after fertilization. The blastomeres at these stages were reduced in size. The cleavage planes were no longer regularly patterned as compared to 2-8 cell stage.

STAGES DURING THE MORULA PERIOD:

• During the morula stage (at 4 h period), the blastomeres were further divided into many cells and accumulated around the animal pole, representing a flowery appearance.

• The blastodermal cells (256- celled stage) appeared after 5h. Here the eggs were appeared as smaller to the previous stage together with the increase in marginal cell was observed. Eggs were round shaped and yellowish white in color.

• After 6h late morula and 512 celled stage occurred.

STAGES DURING BLASTULA PERIOD:

• Shortening along the animal - vegetal axis of embryo was continued up to 7h and they appeared as approximately spherical in shape. This stage is called sphere stage.

• After 8h the blastoderm was flattened down onto the yolk sphere and formed a dome shape structure. In this stage, the egg capsule was yellowish white and round in shape.

• During blastula period, after the period of 9h, the embryonic shield was converted into a thickened margin of the blastoderm at 30% of the entire distance between the animal and vegetal poles.

STAGES DURING GASTRULA PERIOD:

• Epiboly displaced the blastoderm margin to 50% of the distance between the animal and vegetal pole after 10h and after 11h the embryonic shield became more clearly visible and looks like a narrow steak.

• Yolk became semi-lunar shape. The cell migration continued and covered 90% over the yolk sphere called as germ ring, giving a thread like appearance. This germ ring proceeded further with differentiation of slight broader at one end and narrow at other end during 12h indicating future cephalic region and tail, respectively.

• Body axis mostly encircled the vitelline sphere with well-differentiated head and tail, which looked like “C” shape.

STAGES DURING SEGMENTATION PERIOD:

• After 13h of fertilization, eggs were slightly whitish in color.

• Tail and head region was slightly seen 15 and 17h after fertilization respectively.

• Slightly distinct head and tail region was seen with large yolk sac after 19h. Eyes were clearly seen with distinguishable head after 21 h.

• Large yolk sac was present.

STAGES DURING PHARYNGULA PERIOD:

• Head, eye and tail region was clearly seen with large yolk sac after 22h of fertilization.

• One day old embryo was observed with broadened cephalic region with distinct fore brain.

• At 27.5h old embryo, tail was more elongated than before.

• Hatching started after 48h of fertilization. Egg diameter ranged between 1.84-1.85mm.

LARVAL DEVELOPMENT:

• A larva (Latin; plural larvae) is a young form of animal where indirect development was observed through the process of metamorphosis.

• The larva looks completely different from the adult form.

Newly hatched larvae:

• Hatching occurred at about 48h after fertilization where the hatchlings appear as transparent and with an almost round yolk sac.

• Newly hatched larvae were slender, straight and transparent, gradually tapering towards the tail. The hatchlings ranged between 2.5 - 3mm in length.

1h Old Larvae:

•  Notochord was seen.

• Dorsal and Ventral fin fold was clearly observed.

• Large yolk sac was present.

• The total length ranged between 3.2-3.4mm.

5h Old Larvae:

• The total length ranged between 3.5-3.6 mm.

• Large yolk sac was present. Dorsal and ventral fin fold was clearly observed.

9h Old Larvae:

• Fin folds were seen continuously around the tail.

• Total length of larvae ranged between 3.8-3.9 mm.

• Prominent notochord was found.

13h Old Larvae:

• The larvae increased 4-4.2mm in size.

• The fin folds were seen continuously around the tail region.

17h Old Larvae:

• Pegmentation was observed around the whole body.

• The larvae increased 4.2-4.4mm in size. Yolk sac was partially reduced than previous stage.

• The fin folds were slightly around the tail region.

21h Old Larvae:

• Pectoral fins were slightly seen. The total length of the larvae was 4.5-4.6mm in size.

• Yolk sac and the fin folds around the tail region were more reduced than previous stage.

25h Old Larvae:

• Pectoral fins were seen .Yolk sac was more reduced. The total length of the larvae was 4.8-4.9mm in size.

29h Old Larvae:

• Prominent pectoral fins were seen.

• At this stage, the length of the larvae was 5.1-5.2mm. Yolk sac as well as tail region fin folds were more reduced.

33h Old Larvae:

• The total length of the larvae measured between 5.3-5.4 mm. Pectoral fin more prominent.

37h Old Larvae:

• The eyes increased in size and pigmented. Pectoral fin more prominent. The larvae reached to 5.6-5.7 mm in size. Yolk sac was thinne.

41h Old Larvae:

• Pectoral fin well developed. Mouth cleft more prominent. The eyes increased in size. At this stage, the length of the larvae was 5.6-5.8mm. Tail region fin folds were more reduce.

45h Old Larvae:

• Mouth cleft was more prominent. Yolk sac greatly reduced. The larvae reached to 5.8-6 mm in size. Pectoral fin fold well developed. Pelvic fins were seen.

• 49h Old Larvae:

The larvae reached to 6-6.2mm in size. Yolk sac was greatly reduced. Pelvic fin was clearly visible. The larvae were found swimming smoothly and feeding exogenously.