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fwd: enriching artemia


From: lund at umbi_umd.edu (Eric Lund), on 10/29/97 5:02 PM:
Re: Artemia enrichment with essential fatty acid emulsions.

>>>You CAN do this at home.<<

Bill V. wrote:
>Could you expand on this a bit?  Like ....
>Do you put the emulsion in the hatching solution with the
>cysts or after they hatch?
>How long after the BBS hatch do you harvest?

I just went down to the lab and asked the post-doc, Dr. Moti Harel, for a
few specifics on this.  Here's a quick synopsis:

1) When do I add the stuff?

As you all know, hatching times for brine shrimp are temperature-dependent.
Post-hatch development is also temperature dependent, so all times given
here are approximate.  Artemia reach instar 2 (when they can begin feeding)
at about 6 hours after hatching. If you look at artemia with a good hand
lens you can tell when they have molted. Moti suggests dechorionating your
Artemia eggs if you are going to do enrichment since the hatch rate will be
a bit better and it takes 16 hours for them to hatch under standard
conditions relative to 24 hours for regular eggs.  Assuming you don't
dechorionate your eggs and they hatch under your conditions in 24 hours add
Selcon (or equivilent) at 30 hours after starting the shrimp.

2)  How much of the stuff do I add?

How much do you add? I can't say for sure.  The amount to add will vary
with both the amount of eggs you hatch and the lipid/water ratio of the
product used.  The laboratory I work in is currently evaluating different
fatty acid combinations in the phospholipids used for the emulsions as well
as feeding doses and I am not at liberty to discuss specifics.  I have to
believe that existing products on the market give recommended dosages in
their instructions.

3)  When do I harvest the Artemia?

Maximum nutritional enrichment will have occured by approximately 16 hours
after feeding (this is temperature dependent, however).  The commercial
products used in aquaculture recommend 24 hours post feeding for harvest.

4)  How long are the enriched Artemia good for?

You can store the enriched Artemia in a refrigerator for up to 3 days after
enrichment.  Refrigeration slows their metabolism way down and prevents
them from losing too much of their nutritional value.  I believe that
commercial breeders aerate the Artemia during cold storage.  You may want
to run this by your spouse before perminently installing an air pump in the
crisper section of your refrigerator at home ... :-)

5) Can I use lipid emulsions to enrich other foods?

Yes.  There are 2 ways to do this.  The first is to feed the stuff to foods
that can feed on particles in water.  For example, I'd guess that
blackworms would eat it, but Drosophila would probably be a poor choice.
The other way to do it is to dunk the food items in the solution just prior
to feeding.  The emulsion will stick to the food item and be ingested along
with the food by your fish -- think of it like the chocolate coating on an
icecream bar.  This is analogous to the way Herp keepers give nutritional
supplements to their critters.

6)  What are the symptoms of essential fatty acid deficiency?

The essential fatty acid endproduct, DHA, is an important component of cell
membranes in retinal tissue (eyes), neural tissue and cardiac tissue.
Deficiency symptoms include:

Sudden fright syndome:  fish (usually juveniles) go into shock or twitch
convulsively when frightened.

Poor visual accuity:  reduced ability to locate prey.

worn fins

poor growth rates

poor egg viability

high mortality rates under stressful conditions (ie: shipping)

Note that all of these symptoms can be caused by things other than
essential fatty acid deficiency. IMHO essential fatty acid deficiency is
not a problem with most killies fed a varied diet.  It is possible,
however, that supplementation with a lipid emulsion may increase growth
rates, fecundity and fry survivorship.  So, if you are having problems
raising particular species it may be worth a try.  For those trying to
breed reef critters such as anemone fish, gobies and blennies artemia
enrichment is essential for success unless one raises marine rotifers as a
larval food instead.

I hope this proves of use to some of you.


Eric Lund

lund at umbi_umd.edu

P.S.  Feel free to forward this to appropriate lists (ex: livefoods)