by Kai Schumann
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 doesnt 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.
Whats
in it: 1.0 Background 2.0 Hatching Requirements 3.0 Harvesting 4.0 Feeding 5.0
Growing Adults 6.0 Maintanence 7.0 Trouble Shooting 8.0 Artemia Storage 9.0
Decapsulating Artemia Cysts 10.0 Resources 11.0 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.
Top
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 Ive found are separation columns found in any lab supply -
theyre 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 ([email protected]).
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 ([email protected]) 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. Dont 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 doesnt take
alot 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.
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.
Top
FEEDING:
Since artemia are non-selective filter feeders (meaning they dont 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 havent 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
Top
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 dont 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 havent had much problem with water quality, so filtration really
isnt 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.
Top
MAINTANENCE:
Being a low volume operation, water quality can deteriorate rapidly, especially
as biomass increases (I mean, thats 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.
TROUBLESHOOTING:
My artemia just crapout and die - several causes, there could be insufficient
aeration leading to asphyxiation, or you couldnt resist and used that damned
wooden airstone I told you not to use. Or - theyre starving to death. The health
status can be checked by looking at how theyre 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 youve 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 occured, 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.
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, theyve 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
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 dont 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 dont 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 havent 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 grey, 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 immediatly after the
membranes have dissolved as indicated by the color (bright orange or grey),
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%.