- A dry bundh is a fish breeding site where water is not present for most of the year and is filled only during the monsoon season or by artificial methods when needed.
- In dry bundh systems, fish are typically stocked when water is available, and after breeding, the water is removed or dries up naturally.
- Fish lay eggs during the brief wet period, and these eggs hatch before the bundh dries again.
Wet Bundh:
- A wet bundh is a perennial breeding site where water is present year-round, either due to natural springs or an artificial water supply.
- Fish can breed and grow continuously as the water remains in the bundh.
- The presence of water throughout the year allows for more consistent and extended fish rearing and spawning periods compared to dry bundh.
Media and Reagents Used for Cryopreservation of Fish Sperm:
Cryopreservation is a technique used to preserve fish sperm at extremely low temperatures (usually in liquid nitrogen at -196°C) for long-term storage. The key steps include sperm dilution, cooling, freezing, and storage, followed by thawing and fertilization when required. The following media and reagents are commonly used:
- Cryoprotectants:
- Dimethyl Sulfoxide (DMSO): One of the most common cryoprotectants used to protect sperm cells from ice crystal formation during freezing.
- Glycerol: Another cryoprotectant that helps to prevent damage to sperm by minimizing the formation of ice crystals.
- Methanol and Ethanol: In some species, these are used as alternatives to DMSO or glycerol.
- Extender Media:
- Extender solutions are used to dilute fish sperm and maintain sperm viability during the freezing process. These solutions often include:
- Saline solutions (Ringer’s solution, Hanks’ Balanced Salt Solution)
- Sugar solutions (glucose, fructose, or sucrose-based media)
- Buffers (HEPES, Tris) to maintain pH stability.
- Extender solutions are used to dilute fish sperm and maintain sperm viability during the freezing process. These solutions often include:
- Antifreeze Proteins:
- In some cases, antifreeze proteins (AFPs) or antifreeze glycoproteins are added to further protect sperm from freezing damage by reducing ice formation.
- Freezing and Thawing Equipment:
- Liquid Nitrogen: Sperm samples are frozen using liquid nitrogen, which allows for ultra-low temperatures that ensure long-term preservation.
- Programmable Freezers: Specialized freezers that allow controlled freezing rates to optimize sperm viability.
Cryopreservation offers a way to store valuable genetic material, enabling selective breeding programs, conservation of endangered species, and the ability to store and transport fish sperm globally.