Category: Biology Second Paper

Sufficient oxygen, suitable temperature, adequate food, current and turbid water and enemy-free environment are required for good reproduction of roe fish. Cotton fish do not lay eggs without suitable environment. In the absence of a suitable environment, mature eggs are absorbed by the body. This phenomenon is called atresia. Atresia occurs year after year in closed ponds. Therefore, roe fish does not breed in closed reservoirs. Only physical aging occurs. Closed ponds contain more organic waste. Such water has high BOD (Biological Oxygen Demand) value and low O2 content. Regeneration does not occur in stagnant water. When O2 is low, sexually mature fish cannot stimulate the gonads to induce sexual reproduction. Eggs and larvae do not easily fall prey to enemies in the clear water of closed reservoirs. Excretion is uncertain as the water in closed reservoirs fluctuates. So roe are not interested in spawning in stocked ponds.

(i) Fresh water bodies with streams
(ii) Phenyl or foamy turbid water
(iii) Presence of adequate amount of oxygen in water
(iv) Heavy rain with thunder
(v) Upstream hill slopes
(vi) Water temperature 24-28 degree centigrade
(vii) River bends
(viii) Fluctuation of water
(ix) Monsoon and Amavasyaba Purnima Tithi.

1. Oxygen and nutrients are renewed in the flowing water. Embryos and larvae get enough oxygen from water. Dr. Siddiq Publications
2. The continuous flow of water protects the eggs and larvae from predators.
3. The rapid circulation of the flowing water ensures the excretion of fish.
4. Sediment carried by running water makes the water cloudy. Turbid water protects fish eggs and larvae from predators.
5. Flowing water transports fish eggs and larvae. In the new environment, there is enough food for chickpeas and chickpeas. Dr. Siddiq Publications

1. Reservoirs are filled with water during monsoons or floods.
2. Ruhi fish lays eggs in flowing and turbid water.
3. Pona fish need turbid water to survive.
4. The water temperature of the spawning environment will be 24-28 degrees Celsius.
5. Water will have a lot of oxygen.
6. Ruhi fish lays eggs on Amavasya or Purnima.
7. Male fish will secrete steroid hormones in the water to attract female fish for reproduction. Dr. Siddiq Publications
8. The water in the river should be in such a way that the sperm and egg mix.
9. There will be enough food in the environment to allow the chicks to undergo morphological and structural changes.

Morphological and structural changes occur in the fingers. Transforms into a full-fledged fish. attains sexual maturity. When it reaches sexual maturity, it is called brood fish.

If the length of Pona is 7-12 mm then it is called Dhani Pona. When the chick is 9-30 days old, it is called Anguli chick. Fingers, fins, barbel etc. are formed in fingerlings.

In this stage the yolk sac is destroyed. Operculum, dorsal fin, caudal fin etc. arise. Air sacs are divided into two parts. The tail is homocircular. The nostrils are fully divided, the eyes are equal and the fleshy mouth is formed.

Larva emerges from egg within 15-18 hours. The larva is called an egg. Dimpona age of 72 hours is called renupona. In this condition, the embryo takes on a light yellow color. Notochord and nerve cord are formed. Eyes, hearing and chromatophores are formed. Air sacs and digital fins are present.

Cleavage begins 30-45 minutes after formation of the zygote. The zygote divides by cleavage to form micromere and macromere cells. In the process of blastulation, these cells become blastomeres. Blastomere cells are arranged in a certain layer. During gastrulation, blastomere cells are arranged in three layers. Ectoderm, Mesoderm and Endoderm.

The process by which the zygote divides repeatedly into a full-fledged organism is called fertilization. This is done in three steps.
(i) Embryonic cleavage: Cleavage begins 30-45 minutes after formation of the zygote. The zygote divides by cleavage to form micromere and macromere cells. In the process of blastulation, these cells become blastomeres. Blastomere cells are arranged in a certain layer. During gastrulation, blastomere cells are arranged in three layers. Ectoderm, Mesoderm and Endoderm.
(ii) Hatching of larval stage: Larva emerges from egg within 15-18 hours. The larva is called an egg. Dimpona age of 72 hours is called renupona. In this condition, the embryo takes on a light yellow color. Notochord and nerve cord are formed. Eyes, hearing and chromatophores are formed. Air sacs and digital fins are present.
(iii) Post larval hatching: In this stage the yolk sac is destroyed. Operculum, dorsal fin, caudal fin etc. arise. Air sacs are divided into two parts. The tail is homocircular. The nostrils are fully divided, the eyes are equal and the fleshy mouth is formed.