Atemia FAQ 2.0
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Having seen all the posts about brine shrimp questions, I have decided to create
a FAQ for artemia culture. It is by no means the definitive source, and will be
expanded as I collect information. I have gathered this information from various
books, publications and my own experience in raising these guys. There is a
wealth of information out there that gets real scientific, much of this I have
left out as it really doesn't pertain to our goal of growing these critters.
Anyway, here it is, hope you find it to be of use. Any comments or additions to
this FAQ should be directed to me. Kai Schumann (KS@Lilly.com)
Whats in it:
1.0 Background
2.0 Hatching Requirements
3.0 Harvesting
4.0 Feeding
5.0 Growing Adults
6.0 Maintenance
7.0 Trouble Shooting
8.0 Artemia Storage
9.0 Decapsulating Artemia Cysts
10.0 Bibliography
1.0 BACKGROUND:
The common brine shrimp (artemia) is in the phylum Arthropoda, class Crustacea.
Artemia are zooplankton like Copepods and Daphnia, which are also used for live
food in the aquarium. The artemia life cycle begins by the hatching of dormant
cysts, which are encased embryos that are metabolically inactive. The cysts can
remain dormant for many years as long as they are kept dry and oxygen free. When
the cysts are placed back into salt water they are re-hydrated and resume their
development. Artemia cysts are best stored in a tightly sealed container in a
cool dry environment, if possible, vacuum packed. The refrigerator is usually
best.
After 15 to 20 hours at 25 degrees C (77 degrees F) the cyst bursts and the
embryo leaves the shell. For the first few hours, the embryo hangs beneath the
cyst shell, still enclosed in a hatching membrane. This is called the Umbrella
stage, during this stage the nauplius completes its development and emerges as a
free swimming nauplii. In the first larval stage, the nauplii is a brownish
orange color because of its yolk reserves, newly hatched artemia do not feed
because their mouth and anus are not fully developed. Approximately 12 hours
after hatch they molt into the second larval stage and they start filter feeding
on particles of various microalgae, bacteria, and detritus. The nauplii will
grow and progress through 15 molts before reaching adulthood in at least 8 days.
Adult artemia average about 8mm long, but can reach lengths up to 20mm in the
right environment. An adult is a 20 times increase in length, and a 500 times
increase in biomass from the nauplli stage.
In low salinity and optimal food levels, fertilized females usually produce free
swimming nauplii at a rate of up to 75 nauplii per day. They will produce 10-11
broods over an average life cycle of 50 days. Under super ideal conditions, an
adult artemia can live as long as three months and produce up to 300 nauplii or
cysts every 4 days. Cyst production is induced by conditions of high salinity,
chronic food shortages and/or cyclic oxygen stress ( less than 2 mg/l).
Adults can tolerate brief exposures to temperatures as extreme as -18 to 40
degrees C (0-104 degrees F) Optimal temperature for cyst hatching and adult grow
out is 25-30 degrees C (77-86 degrees F), but there are differences between
strains, optimum for the San Francisco bay strain is 22 degrees C as compared to
30 degrees C for Great Salt lake artemia. Brine Shrimp prefer a salinity of
30-35 ppt (1.022-1.026 density) and can live in fresh water for about 5 hours
before they die. Caution should be used to not over feed in a fresh water
aquarium because of the rapid decomposition of the dead. Many fresh water fish
will tolerate and even thrive in a brackish water environment of 1-5 ppt easily,
so it is possible to add saltwater to the tank and extend the survival of the
artemia if required.
Other variables of importance are pH, light and oxygen. A pH of around 8 is
best; pH less than 5 and greater than 10 will kill the culture. the pH can be
increased with baking soda, and lowered with muriatic acid. Strong illumination
is necessary for hatching. A standard growlite bulb available in an aquarium
supply is adequate. Most important is the level of oxygen in the water, with a
good oxygen supply, the artemia are a pale pink or yellow, or if they are
heavily feeding on microalgae they will look green in color. In this ideal
condition growth and reproduction is rapid, and a self-sustaining artemia supply
is possible. If there is a low oxygen level in the water with large amounts of
organic matter, or a high amount of salinity from evaporation, the artemia will
feed on bacteria, detritus and yeast cells, but no algae. It is under these
conditions that they produce hemoglobin and look red or orange in color. If this
environment remains they will start producing resting cysts, and the colony may
crash. It is very important to have a vigorous air supply in the tank for two
reasons, one is to keep the available food supply in suspension where it can be
filtered out, and the other is to promote a good oxygen supply in the system.
2.0 HATCHING REQUIREMENTS:
The optimal conditions for hatching artemia are as follows - 25 degrees C,
salinity - 5 ppt (1.030 density), heavy continuous aeration, light - 2000 lux
constant illumination, pH around 8. Good circulation is essential to keep the
cysts in suspension. A container that is V shaped is best (two liter bottles
work good, the absolute best I've found are separation columns found in any lab
supply - they're expensive though). glue a valve on the cap and invert, this way
unhatched cysts, empty shells, and hatched nauplii can be easily removed
separately. Another idea I would highly recommend checking out was offered by
Ken Cunningham (kfc@wimsey.com). His discovery was to use pilsner beer glasses,
Some of them have a conical point at the bottom, these are the ones to look for.
Ken places three or four in a ten gallon tank and heats them by the water bath
method. Put rigid air lines in the glasses with no air stones, connected by
flexible tubing to the distribution manifold. 80 degrees, bright light at all
times. In each glass put 1/2 teaspoon of salt, 1/2 or 1/4 teaspoon of cysts, and
bubble for 24 hours. To harvest, leave the rigid tubing in the glass, but lift
it out of the aquarium and disconnect the flexible air tube at the manifold. Let
the glass settle in relative darkness (i.e. not bright light) for 10 minutes,
and siphon the artemia out using the airline tubing into fresh water to rinse.
By using the glasses on a rotation, its possible to have hatched artemia
available at all times. Still another good idea comes from Wright Huntley
(huntley@ix.netcom.com) who originally got the idea from Oleg Kiselev. Wright
now uses Chianti wine bottles found at Trader Joes for 4 bucks. By tilting the
bottles on edge and using the same salt and cyst ratio as Ken, quite high hatch
rates are being obtained. harvesting is the same, by siphoning using the air
tubing, but into a funnel lined with a handkerchief, then the artemia may be
rinsed if desired, and fed. There are many methods in use for hatching these
guys. Once you play with whatever particular method you chose to achieve optimum
performance, your results will probably be just as good as any other hatching
method. Don't be afraid to experiment.
The hatching percentage and density are usually a function of water quality,
circulation and origin of the cysts. Containers with flat bottoms have dead
areas in the corners and are not ideal for maximum hatch rates. It doesn't take
a lot of cysts to get going, there are usually 200,000 to 300,000 nauplii per
gram of cysts, so a half teaspoon in a two liter bottle is more than enough for
the typical aquarist. With a setup of two or more bottles, one started one day,
the other the next, you can have a continuous supply of newly hatched artemia
for that reef tank every day. This is the method we used when I worked at
Scripps Aquarium - only with 5 gallon water bottles.
3.0 HARVESTING:
Harvest the nauplii by turning off the air, or remove the air stone, and let the
culture settle for about ten minutes. Hatched, empty shells float to the
surface, and unhatched cysts will sink to the bottom. The newly hatched nauplii
will concentrate just above the unhatched cysts on the bottom. Since the newly
hatched nauplii are attracted to light (phototropic), by shining a flashlight at
the center of the bottle, you can concentrate them where it is easy to siphon
them off, or drain the cysts off the bottom by using the valve, then drain the
nauplii onto another container. The unhatched cysts should be used in the next
culture and not thrown away, since part of them might hatch with the next batch.
4.0 FEEDING:
Feeding - Since artemia are non-selective filter feeders (meaning they Don't
care what they pick out of the water), a wide range of food has been
successfully used. The criteria for food selection should be based on particle
size, digestibility, and solubility (powdered milk wont work). Feeds that have
been used include live microalgae such as nanochloropsis and a wide variety of
inert foods, which are far more practical for us aquarists. One caveat with
inert foods is to be careful not to overfeed. Inert feeds include yeasts, both
active and inactive (a brewers supply is the best source, bread yeast is
expensive!) micronized rice bran, whey, wheat flour, soybean powder, fish meal,
egg yolk, and homogenized liver. ( I haven't used the last four). Dried
microalgae such as spirulina has also been used with success (available from
health food stores, but again kind of expensive). The simplest way to measure
food levels in the tank is by figuring the transparency of the water. This is
done with a dowel with measuring marks marked off in centimeters, and a white
disk with black fields on it is glued on the end. The depth where the contrast
between the white and black fields just disappears measures the light
penetration into the tank. The more stuff floating around the tank, the less
transparency. With a stocking density of 5000 nauplii per liter, the
transparency should be 15-20 cm the first week, and 20-25cm thereafter. Of
course it is best to maintain an optimal food level at all times, so frequent
feedings, or better yet, a continuous drip feeding are mandatory for optimal
grow out.
Food is not directly consumed, but rather transferred to the mouth in a packaged
form. The space between an artemias legs widens as the legs move forward. Water
is sucked into this space from below, and small filtering hairs collect
particles including food from the incoming stream. On the back stroke the water
is forced out and the food remains in a groove at the base of the legs, this
groove has glands that secrete an adhesive material that clumps the food into
balls, and microhairs move the food packages toward the mouth. The optimal size
for food should be less than 50 - 60 microns.
5.0 GROWING ADULTS:
When feeding larger fish and invertebrates where small food is not needed, adult
artemia may be preferred over nauplii. But why should you bother growing adults
you ask? I will just feed more newly hatched brine shrimp to make up the
difference you say... Well, adult artemia are 20 times longer and 500 times
heavier than nauplii and therefore provide more of a meal. There is a myth
floating around that adult artemia are not as good for your fish as newly
hatched. There is a tiny bit of truth to this, but it depends on what you are
feeding. So whats in it for your fish: Newly hatched artemia are high in fats,
about 23% of dry weight. By mid juvenile stage, the fat levels have decreased to
about 16 %, and by the time they are pre-adults the fat levels have decreased to
about 7%. But, at the same time, the protein content has risen to replace the
fat, from about 45% in a newly hatched artemia to about 63% in an adult. Based
on this, you should determine what is best for your tank, young fish larvae
require a high fat intake for growth and health, while older juveniles and
adults need protein for health and reproduction. Also, nauplii are known to be
deficient in several essential amino acids, while the adult artemia are rich in
all essential amino acids. Adult artemia therefore supply more biomass than
nauplii and are more nutritionally complete.
The best approach to growing adults is to pick up a 10 or 20 gallon glass
aquarium cheap someplace. Take thin acrylic sheet or formica, and jam it in the
tank, essentially making an oval tank. ( this is important to remove the
previously mentioned dead spots, and improve circulation ) Glue all the seams
with silicone (3M - Blue tube). Circulation can be enhanced by gluing a
partition down the middle of the tank making a raceway arrangement. Best yields
are obtained with a good food circulation, animal distribution, and strong
aeration. This next step is the hardest to explain without pictures, You need to
make six or eight (depending on the length of your tank) air lift tubes. These
are simply 1 inch thin wall PVC, cut at 45 degrees on the bottom, with a 90
degree elbow on top. The water level should reach the middle of the elbow, with
the tube touching the bottom of the tank, 45 degree cut down. Drill a hole in
the 90 degree fitting so you can feed an airline 3/4 of the way down the tube.
Glue these tubes to the center divide so that the 90 degree elbows all face the
same direction at a 45 degree angle to the divider. Your creating a mechanism to
make a constant flow of water in a clockwise or counter clockwise direction (I
Don't think it matters which).
Here is where I should bring up the subject of aeration, avoid the temptation to
put in wood airstones to increase flow and aeration. Yes they make beautifully
fine bubbles and you can get excellent upflow with them. But its these same fine
bubbles that will wreak havoc with your artemia. Artemia can lodge air bubbles
in the swimming appendages or even ingest them, making them float so that they
are unable to feed which will eventually kill them.
I haven't had much problem with water quality, so filtration really isn't
necessary on the small scale that were on. Filtration can be included if You
feel so inclined, but it will require a screened overflow to a sump or cartridge
filter.
Moderate aeration with coarse or no airstones, good water quality, and generally
clean conditions are all important for raising high densities of adult brine
shrimp. Since the artemia feed constantly, faster growth rates and better
survival is achieved by multiple or continuous feeding over a 24 hour period.
Best growth rates are achieved at 25-30 degrees C with salinities of 30-50 ppt
and LOW light levels. Remember, artemia are drawn to strong light, so if you
install that 175 watt metal halide lamp you had leftover from the reef tank, the
little buggers are going to increase their swimming activity and have greater
energy expenditure, resulting in slower growth rates. In low light the artemia
will spread out in the water column, swimming slowly and achieving more
efficient food conservation.
6.0 MAINTENANCE:
Being a low volume operation, water quality can deteriorate rapidly, especially
as biomass increases (I mean, That's the whole idea right?). The problem usually
occurs because of over feeding, which leads to fouling and low oxygen levels.
There is a fine line between optimal feeding levels and wiping out our tank,
especially when using non-living foods. To help overcome this problem, you need
to take care of your artemia tank as much as you pay attention to your aquarium.
Here is what you do: Clean the bottom every couple of days. You do this by
turning off the air, letting the tank settle, and using that handy flashlight
again (I find this works best when done at night) By now we know what our little
buddies are going to do. Meanwhile siphon the crap off the bottom of the tank,
remember, these guys are going to molt 15 times before becoming adults. (unless
you have three hands, prop the flashlight on something). About a 20% water
change per week is adequate.
7.0 TROUBLESHOOTING:
My artemia just crapout and die - several causes, there could be insufficient
aeration leading to asphyxiation, or you couldn't resist and used that damned
wooden airstone I told you not to use. Or - they're starving to death. The
health status can be checked by looking at how they're swimming, shine your
flashlight into the tank, and they all should rapidly concentrate at the source,
this is good. However, slow dispersed swimming indicates things are going to
hell quick. If you have access to a microscope you can examine their digestive
track, which should be full of food (assuming you've been feeding them, and you
have right?) If the swimming appendages and mouth region are clean, this is
good. If they are covered with food particles, this is bad. This condition could
be due to the nature of the food or the physiological condition of the animals.
Another reason suggested is that a virus infection has occurred, very little is
known about this, and it is impossible for us aquarists to confirm this has
happened - see the decapsulation section at the end of this FAQ.
Slow growth - Temperature is too low, pH imbalance, salinity is off, inadequate
food or lousy food quality.
8.0 ARTEMIA STORAGE:
Your artemia can be stored for future use in several different ways, adult
artemia will survive for several days in the refrigerator (if your wife will let
you, mine wont) If you refrigerate them, be sure to warm them up and give them
one last feeding before you feed your fish. this will restore their nutritional
quality, after all, they've been starving for the past couple of days. You can
also freeze them, nope, fraid this kills them. An ice cube tray works perfect
for this (here we go with the wife again, I cant do nuthin) Be sure to freeze
them in 7-8 ppt saltwater for best results. Freezing is neat because all you
have to do is toss an artemia cube into the tank, and you have a nifty time
release food supply. You have to be careful not to over feed here, they float to
the bottom and decompose quick, and you can bomb your tank rather rapidly.
9.0 DECAPSULATING ARTEMIA CYSTS
Having had several questions on how and why this is done, I have decided to
include this procedure at the end of this FAQ. It is an involved process and not
many people will choose to perform it, but it is good information to have in
case you get a wild hair some day, or just want to impress your friends.
Separating nauplii from their shells may be desirable for several reasons. Cyst
shells are indigestible and can lodge in the gut of predators causing fatal
obstructions, the shells have been speculated to be a source of heavy bacterial
contamination, the nutritional content is believed to be higher because the
nauplii Don't have to spend energy to break out of their cysts, because of this
the hatching ratio increases, and finally the de-cysted cysts can be fed to fry
too small to eat hatched nauplii. My thanks to Mike Noreen for the last three
reasons! While in all my years of messing with these guys, I have never heard of
anyone having problems with either of the first two scenarios, quite a few
commercial aquaculture ventures go to the trouble of decapsulation.
Decapsulation is accomplished in four steps: re-hydrating the cysts, treating
with the decapsulation solution, washing and deactivating the residual chlorine,
and the hatching of the embryos.
Dry cysts have a dimple in their shell which makes it hard to remove the
complete inner membrane. For this reason, the cysts are first hydrated into a
spherical shape. The cysts should be re-hydrated in soft or distilled fresh
water at 25 degrees C for 60-90 minutes. The lower the temperature, the longer
it takes to re-hydrate them. But, no matter what the temperature, never leave
them longer than 2 hours, as by this time some of the cysts will have restarted
their metabolisms and will therefore not survive the decapsulation procedure.
Hydration should be done in a container identical to the one used for hatching
regular cysts for the same reasons of circulation and aeration. Cysts should be
filtered on a 100- 125 micron collection screen and rinsed, but this step may be
missed if you Don't have the screen. It is best to decapsulate the hydrated
cysts immediately, but they can be refrigerated for several hours if needed.
During the hydrating process, you need to prepare your chlorine solution. Either
household liquid bleach or powdered pool chlorine is mixed with salt water.
In preparation for decapsulation the cysts are placed in a pre-cooled buffered
solution, 4 degrees C and about pH 10, consisting of 0.33 ml of 40% sodium
hydroxide (NaOH) and 4.67 ml of sea water per gram of cysts ( you may have a
hard time finding pure NaOH, most pharmacies should have it though, I got some
from work so I haven't really looked much). The buffer solution is prepared by
dissolving 40 grams of sodium hydroxide in 60 ml of fresh water. Decapsulation
will begin when you add 10 ml of liquid bleach to the buffer solution. You will
need to have a thermometer in the brew, because the chemical reaction taking
place gives off heat. It is important to keep the solution between 20 and 30
degrees C. Starting with pre-cooled buffered seawater makes it easier to keep
the reaction in the right temperature range. If you need to, an ice cube or
blu-ice packs can be added to help drop the temp.
A second method is to add 0.70 grams of dry pool chlorine powder per gram of
cysts. In this case the buffer is sodium carbonate consisting of 0.68 grams
sodium carbonate in 13.5 ml water. It is easier to split the water in two equal
parts, add the required amount of chlorine to the first part, and the sodium
carbonate to the second. Allow them to dissolve and react, which will cause a
precipitate. Pre-cool the two solutions, and mix them together, then add the
hydrated cysts. During decapsulation, stir the brew continuously to minimize
foam formation, and to dissipate heat. Note the color of the solution, it will
change from a dark brown to gray, to white, and then to a bright orange. This
reaction usually takes 2-4 minutes. With the calcium hypochlorite solution, the
cysts will change only to gray, and will take about 4-7 minutes.
The cysts must be filtered from the solution quickly and immediately after the
membranes have dissolved as indicated by the color (bright orange or gray),
otherwise you will simply dissolve the whole cyst instead of only the outer
shell. The chlorine should be washed off the cysts by rinsing with fresh water
or salt water until you cant smell the chlorine anymore. The residual chlorine
attaches itself to the decapsulated eggs, and has to be neutralized. Do this by
washing the cysts in a 0.1% sodium thiosulfate (0.1 gram sodium thiosulfate in
99.9 grams water) for one minute. An alternative method uses acetic acid (1 part
5% vinegar to 7 parts water). The first method works better, but the second
method is easier as everyone has the materials in their kitchen. The cysts are
then re-washed with fresh or salt water and placed into the hatching container,
and hatched as normal artemia. The decapsulated cysts can be hatched
immediately, or stored in the refrigerator for up to 7 days before hatching. For
long term storage, like the expensive stuff you can buy, the cysts need to be
dehydrated.
Dehydration of the decapsulated cysts is done by transferring your one gram of
decapsulated cysts into a saturated brine solution of 330 grams salt to 1 liter
water. Aerate this for 18 hours, replacing the solution every 2 hours. The cysts
are releasing their water through osmosis in the solution, so it is important to
keep the salt concentration high. After 18 hours, the cysts have lost about 80%
of their cellular water, stop the air flow and let everything settle, then
filter the cysts out. These cysts can then be placed in a container and topped
off with fresh brine solution. seal the container and store it in the
refrigerator or freezer. Cysts with 16-20% cellular water can be stored for a
few months without a decrease in hatching rate. For a longer term storage, you
have to reduce the cellular water content to less than 10%.
11.0 Bibliography
Here are some of the articles I studied to compile this FAQ (not a complete
listing, as I read hundreds). Most of whats here cant be found in the average
library, but may have to be ordered from a university library or marine
institution. I want to thank the librarians at the Scripps Institution of
Oceanography, and Dr. Sorgeloos of the Artemia Reference Center for helping me
locate all of this information.
Hunter J.R. 1981. The Essentials of Brine Shrimp, Farm Pond
Harvest. Fall issue, pp 17-18.
Persoone G., Sorgeloos P., Roels O., Jaspers E. 1980. The
Brine Shrimp Artemia. Volume 3, Ecology, Culturing and use in
Aquaculture. Universa Press, Wettern, Belgium.
Reeve M.R. 1963. Growth efficiency in Artemia under
laboratory conditions, Biological Bulletin 125:133-145.
Dhert Philippe, Sorgeloos Patrick. Live Feeds in Aquaculture,
Infofish International, 2/95 pp. 209 - 219.
Sorgeloos Patrick. Bioengineering of Hatcheries for marine
fish and Shellfish, Journal of Marine Biotechnology, 1995.
Lavens Patrick, Sorgeloos Patrick. Production of Artemia in
Culture Tanks. Chapter 13, Artemia Biology. CRC Press, Boca
Raton, FL. 1991
Various abstract papers supplied from Dr. Sorgeloos,
Laboratory of Aquaculture & Artemia Reference Center,
University of Gent, Belgium.
Information Pack supplied from San Francisco Bay Brand Artemia