Developed by the Harbor Branch ACTED staff Live Feeds: Artemia Developed by the Harbor Branch ACTED staff

Live Foods Fish larvae must be fed live foods which have the nutrition and enzymes (exogenous) they need, before their own digestive system is formed. After the fish has developed its own digestive system, then weaning to dry feed can begin.

Live Foods The two main live feeds commonly used : Rotifers Artemia (brine shrimp) Other live feeds include: Mollusc trochophore larvae Ciliates Copepods Wild plankton

Live Foods Most commercial hatcheries rely on rotifers and Artemia, for their ease of production, cost and reliability.

Rotifers Rotifers can be produced using algae, yeast, or other custom products, or a combination. Rotifer production range from 100 to 10,000 animals per ml. Rotifers are usually maintained in larvae tanks at a density of 5 to 30 per ml of larval tank water.

Brine Shrimp, Artemia Photograph by HBOI

Brine Shrimp (Artemia) Artemia can be hatched in 17 liter containers with hatches of 5 to 10 million. Artemia are maintained at less than 1 per ml of culture water.

Brine Shrimp (Artemia) Newly hatched brine shrimp have maximum nutritional value. Artemia lose their nutritional value after 10 - 12 hours. At this time Artemia begin to feed and may be enriched with various products including algae. After 24 hours, the enriched Artemia is fed to larvae.

Brine Shrimp (Artemia) Most enrichment products increase the fatty acid content of the shrimp which is beneficial to larvae. Other beneficial products can be incorporated into Artemia, including: Probiotics Medications

Conventional Hatching for Marine Fish (No de-capsulating) 1. 8 a.m. Disinfect cysts with chlorine and hydrate cysts for 1 hour in freshwater. 2. Chlorinate hatching saltwater, de-chlorinate, and check for residual chlorine. 3. 9 a.m. Drain cysts into net, rinse and add to saltwater. Add de-foamer. 4. Next day 8 a.m. Turn off air and let settle until shells, nauplii and unhatched cysts are separate, about 15 minutes. Drain unhatched cysts on the floor, then drain shrimp in net, stopping before the shells begin. 5. Rinse shrimp with salt water, and then put in a bucket of saltwater. 6. Remove as many floating shells as possible with a baster. 7. Feed to larvae.

Hatching for Freshwater Fish (No de-capsulating) 1. 8 a.m. Add salt to freshwater. 2. Add cysts straight from the can. 3. Next day 8 a.m. Turn off air and let settle until shells, nauplii and unhatched cysts are separate, about 15 minutes. Drain unhatched cysts on the floor, then drain shrimp in net, stopping before the shells begin. 4. Rinse shrimp with freshwater. 5. Feed to larvae.

Hatching with De-capsulated cysts 3 p.m. Add de-capsulated cysts to seawater. Add de-foamer. 2. Next day 7 a.m. Turn off air and drain immediately into net and rinse. 3. Feed to larvae.

Advantages of De-capsulating Cysts must be disinfected with chlorine when using Artemia for saltwater, to kill bacteria such as Vibrio. 2. Cysts do not need to be hydrated before hatching, saving time. 3. With no shells, nauplii can hatch quicker with less expenditure of energy (fat content), increasing their nutritional value.

Advantages (continued) 4. Hatching time is reduced from the normal 24 hours to 16 hours at 30˚C (86˚F). Nauplii lose their nutritional value over time, so the extra 8 hours saved means a nauplii with higher fat content. 5. Quicker hatching time results in smaller, more uniform-sized nauplii suitable for the smallest sized larvae. 6. There are no shells or unhatched cysts to separate from the nauplii. Even unhatched cysts can be eaten by larvae.

Advantages of De-capsulating 7. There are no shells or unhatched cysts accumulating on the surface of larval tanks. Shells or unhatched cysts can lodge in the esophagus and gut and kill larvae. 8. Hatching percentage increases compared to conventional hatching of unde-capsulated cysts. 9. It is cost efficient as the price of Artemia has doubled. 10. As Artemia supply can fluctuate, even poorer grades (quality) of cysts (such as Grade A or B) can be used.

Disadvantages of De-capsulation 1. De-capsulation requires skilled labor as the window of de-capsulation is only 2 to 4 minutes. Any errors in following procedures result in loss of time and cost of Artemia cysts and chemicals. 2. For large scale hatcheries when several cans must be hatched every day, following the disinfection / hydration techniques is more time and cost efficient.

De-capsulating Brine Shrimp Approximately 275,000 cysts/ gram produce 200,000 – 250,000 nauplii/ gram or 90 – 113 million per 1 pound can (454 grams)

Materials For De-capsulating 1. Pre-cool (5ºC) 1 gallon of salt water and 1 gallon of liquid chlorine (10%) in a refrigerator for at least 2 days. 2. Dissolve 20 grams (1/16 cup) of sodium hydroxide Na(OH)2 beads in 30 ml (1/8 cup) of freshwater. Caution mixture is very hot and can burn skin. Do not inhale fumes! 3. Dissolve 1/4 cup of sodium thiosulfate in a 1 liter beaker of freshwater. 4. Prepare 4 gallons of brine solution (5 lbs. of crystal salt dissolved in 5 gallon capacity bucket of freshwater). 5. 1 pound can of Brine Shrimp cysts.

Photograph by HBOI Photograph by HBOI

Method For De-capsulating 1. Aerate cysts for 1 hour in 15 liters of freshwater in a brine shrimp net suspended in a hatching cone. 2. Rinse cysts briefly in freshwater. 3. Add the Na(OH)2 solution to 2 liters of chilled salt water. Discard remaining salt water.

Photograph by HBOI

Method For De-capsulating 4. Add cysts to empty clean cone. 5. Add the 2 liters of salt water mixture. Aerate vigorously. 6. Add 2 liters of chilled bleach to cone. 7. After 2 - 4 minutes, cysts will turn bright orange.

Photograph by HBOI

Photograph by HBOI

Photograph by HBOI

Photograph by HBOI

Photograph by HBOI Photograph by HBOI

Methods (continued) 8. Add 1 liter of sodium thiosulfate solution and 15 seconds. 9. Turn of the air, drain, rinse with water in a brine shrimp net. 10. Add 2 liters of brine solution to a clean cone. Add cysts and rinse net with more brine and fill up to the line for the required number of cups. For example, the number of cups (18) times 200 ml = 3.6 liters water and cysts.

Photograph by HBOI

Method (continued) 12. Aerate slowly for 18 hours. 13. With continued aeration, drain cysts into 16 to 24 (average 18) - 200 ml containers 14. Refrigerate for up to 2 weeks.

Photograph by HBOI

Photograph by HBOI

Photograph by HBOI

Photograph by HBOI

Photograph by HBOI

De-capsulation costs per pound can Liquid chlorine Less than $2.00 Sodium hydroxide Less than $0.25 Sodium thiosufate Less than $0.25 Labor time Less than 30 minutes