Those who breed fish are well aware that for fry to get off to a good start, they must be well fed. Among the many live foods that are suitable for small fry, perhaps one of the most popular are baby brine shrimp, or nauplii. These can be fairly easily hatched in the fishroom and are relished by most fry large enough to eat them. The dried eggs store well, sometimes for years. Standard hatching procedures involve salt, water, heat, and light, then harvesting of the free swimming nauplii for feeding.
In recent years, decapsulation (removal of the chorion layer) of brine shrimp eggs before feeding has become more popular. There are several advantages to this process:
1. The strong chlorine (oxidizing solution) completely sanitizes the cysts, reducing potential introduction of bacteria or disease.
2. No separation of shells is required when feeding the naupli.
3. There is no loss of unhatched cysts; even those that do not hatch are edible, since the thin "hatching membrane" that is left is digestible. Also, unhatched nauplii have expended no energy stores in swimming.
4. The hatching nauplii require less energy to hatch, which can increase the hatch rate 10% over undecapsulated cysts.
The process of decapsulating brine shrimp eggs need not be a mystery. In the paragraphs that follow, two breeders share their techniques.
"I've been decapsulating brine shrimp eggs with good success using the following formula," says Chris Graseck.
1. Soak 1 tsp. of brine shrimp eggs in 3 oz. of cold water for one hour to rehydrate them.
2. After they have rehydrated, add 2 oz. of bleach and stir for 3-5 minutes. The eggs will change color, from brown to gray to gold. Remember to keep stirring; you're done when the mixture turns golden.
3. Pour through a brine shrimp net and gently rinse with cool water until no smell of bleach remains.
4. In a separate container, prepare a mixture of one cup cool water and one tbs. of white vinegar. Use a low, wide mouth jar you so can drape the net with the eggs over the top to let the eggs soak for a minute or two. This will neutralize any leftover bleach.
5. Place the brine shrimp eggs in salt water and hatch normally. If you hatch out these the regular way and have a lot of orange dead shrimp at the surface cut back a little on the bleach.
Jay Exner's technique is similar.
"You will need: a small bowl (I use one of those tiny clear Pyrex bowls), bleach, brine shrimp eggs, a fine mesh net, and dechlor liquid. To the small bowl, add the brine shrimp eggs you wish to decapsulate. Pour bleach directly on the eggs. You may add some water, it doesn't matter. Gently agitate the bowl. After a few minutes you should notice the color changing. When ready, pour the mixture into the brine shrimp net while holding it over the sink. Rinse the bowl out into the net, then gently rinse tap water through the net. Add dechlor liquid (a few teaspoons) to the empty bowl with a small amount of water, then dip the net into this for a few moments. You can pour the dechlor water through the net and gently rinse the net and eggs one more time. (It shouldn't smell like bleach anymore). Add eggs to culture."
-- G.C.K.A. Newsletter, January 1999
In recent years, decapsulation (removal of the chorion layer) of brine shrimp eggs before feeding has become more popular. There are several advantages to this process:
1. The strong chlorine (oxidizing solution) completely sanitizes the cysts, reducing potential introduction of bacteria or disease.
2. No separation of shells is required when feeding the naupli.
3. There is no loss of unhatched cysts; even those that do not hatch are edible, since the thin "hatching membrane" that is left is digestible. Also, unhatched nauplii have expended no energy stores in swimming.
4. The hatching nauplii require less energy to hatch, which can increase the hatch rate 10% over undecapsulated cysts.
The process of decapsulating brine shrimp eggs need not be a mystery. In the paragraphs that follow, two breeders share their techniques.
"I've been decapsulating brine shrimp eggs with good success using the following formula," says Chris Graseck.
1. Soak 1 tsp. of brine shrimp eggs in 3 oz. of cold water for one hour to rehydrate them.
2. After they have rehydrated, add 2 oz. of bleach and stir for 3-5 minutes. The eggs will change color, from brown to gray to gold. Remember to keep stirring; you're done when the mixture turns golden.
3. Pour through a brine shrimp net and gently rinse with cool water until no smell of bleach remains.
4. In a separate container, prepare a mixture of one cup cool water and one tbs. of white vinegar. Use a low, wide mouth jar you so can drape the net with the eggs over the top to let the eggs soak for a minute or two. This will neutralize any leftover bleach.
5. Place the brine shrimp eggs in salt water and hatch normally. If you hatch out these the regular way and have a lot of orange dead shrimp at the surface cut back a little on the bleach.
Jay Exner's technique is similar.
"You will need: a small bowl (I use one of those tiny clear Pyrex bowls), bleach, brine shrimp eggs, a fine mesh net, and dechlor liquid. To the small bowl, add the brine shrimp eggs you wish to decapsulate. Pour bleach directly on the eggs. You may add some water, it doesn't matter. Gently agitate the bowl. After a few minutes you should notice the color changing. When ready, pour the mixture into the brine shrimp net while holding it over the sink. Rinse the bowl out into the net, then gently rinse tap water through the net. Add dechlor liquid (a few teaspoons) to the empty bowl with a small amount of water, then dip the net into this for a few moments. You can pour the dechlor water through the net and gently rinse the net and eggs one more time. (It shouldn't smell like bleach anymore). Add eggs to culture."
-- G.C.K.A. Newsletter, January 1999