The Free On-line Aquaculture Dictionary

Decapsulation of brine shrimp

Sodium hypochlorite method Calcium hypochlorite method

Why Decapsulate?

There are several advantages for decapsulating or removing the thick outer shell (chorion) of the brine shrimp cyst.

  1. For starters, the strong chlorine or oxidizing solution completely sanitizes the cysts, reducing introduction of bacteria and diseases to your aquarium.
  2. Harvesting brine shrimp Nauplii from decapsulated cysts means that no separation of the shells is necessary. Just pour everything into a mesh net, rinse, and feed to your fish!
  3. Even the un-hatched cysts are edible! An un-hatched decapsulated cyst is left with a thin "hatching membrane" which is easily digested by young fish and invertebrates. An un-hatched brine shrimp embryo also contains more energy than a hatched, swimming brine shrimp Nauplii.
  4. The brine shrimp embryo also requires less energy to break through a hatching membrane than a thick outer shell. This can increase your hatch rate another 10% over un-decapsulated cysts!

Method 1 Sodium hypochlorite per 500g cysts 

Requirements  

4.77 litres sodium hypochlorite (6.5% chlorine)

75 g sodium hydroxide

2.2 litres fresh or seawater

Freshwater 3 litres 

Dissolve the sodium hydroxide in the water and allow to cool. Rehydrate the cysts in 3 litres of well aerated fresh water for 30 60 minutes. Add cysts and hypochlorite to sodium hydroxide solution. Cysts will change from brown to orange., after 4-5 minutes, when orange colour is detected, pour quickly through a sieve and rinse with freshwater. To ensure decapsulation has finished, stir cysts in 0.1 normal HCL for 30 seconds to neutralise the chlorine. Sieve and rinse again. Temperature should not be allowed to exceed 37oC during decapsulation, and ice may be added to maintain low temperature.

Method 2 Calcium Hypochlorite per 500g cysts

325g calcium hypochlorite

340g soda ash

675 litres fresh or seawater

Dissolve all the calcium hypochlorite in 3.38 litres of the water, and in a separate container dissolve the soda ash in the remaining water. Allow for any insoluble particles to settle and decant. Discard the settled solids. Rehydrate the cysts in fresh water with rigorous aeration and add mix the cysts and the two solutions together. Decapsulation occurs within 5-7 minute (when the cysts begin to turn orange from brown). Then proceed as per method 1.