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Light during hatching of bs

>From: ruddigar at home_com
>Subject: Re: Low bbs Hatch  no light
>My first hatch was great!  there was no light on the tank then, but
>like you say, the hatch rate has gone down.  I leave a fluorescent room
>light on now.  Do you think that will suffice?  Or should I place a
>light directly over the hatch tank?
>  I know it is recommended to use 2L pop bottles to hatch bbs, but I
>don't have a way of keeping them at a constant temp. over 70F. Would
>just placing these bottles in the heated tank work?
>  Thanks for the help.
>Jason Miller

I do not have my library at hand right so I have to do this by heart. In 
literature you can read that most Artemia strains need at least a short 
period of light in order to break the diapause condition of the brine 
shrimp eggs (cysts). One presumes that the light stimulus is responsible 
for changing the structure of a haem-pigment located in the chorion 
(=outer layer) of the brine shrimp egg. This certain pigment (exact 
structure is not known yet) blocks some other pigments which need to be 
activated by light in order to induce some intracellular changes (one is 
not sure about what exactly happens) in the eggs which are mandatory for 
enabling the cysts to break the diapause. Now, when brine shrimps are 
being harvested and processed, they are being subjected to light; so one 
might presume that these light stimula have been given to the brine 
shrimp eggs. However, in the industry we still provide some light when 
conducting Artemia hatching tests.

Do not spend too much time/energy on light but focus on temperature and 
aeration instead. An  optimal temperature of about 28 C (82 F) would be 
best. The lower the temperature the longer it takes for the brine shrimp 
to hatch. As you have to wait longer to get a decent yield, the brine 
shrimp which hatched first are consuming their yolk reserves, hereby 
lowering their nutritional value!

You can indeed hatch them “au bain marie” by submersing your hatching 
cone or bottle in a warm aquarium (this takes a lot of light away so 
provide some extra light, e.g. an 60 to 100W light bulb about 20 cm 
away). I find this an easy way.

Also make sure to buffer your hatching medium. This is very important as 
the baby brine shrimp secrete an enzyme (the gland is located in the 
head region of the baby brine shrimp) during the hatching process which 
helps them in breaking through the cyst shell. This particular enzyme is 
most active at higher pH-levels, i.e. the enzyme can not perform its 
function as well at lower pH-levels. So try to keep the pH high enough 
(around 8 to 8.5). Important!

Keep all cysts suspended in the water column during hatching; provide a 
moderate aeration as too strong an aeration will result in a lot of 
cysts being “thrown” against the wall of the cone above the water level 
where they will remain and consequently not hatch. Prevent too small air 
bubbles as the emerging baby brine shrimp may stick to these bubbles 
which may reside on the water surface.

I would also not use the hatching medium more than once as glycerol is 
being released in the medium during hatching. This forms a perfect 
substance for bacteria to grow on. These bacteria will also be present 
on your baby brine shrimp and subsequently you introduce quite a lot of 
bacteria into your fish tank!

Hope this will help you.
Steve Geerts

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