RE: NANFA-- JellyFish

Crail, Todd (
Wed, 2 Oct 2002 10:33:31 -0400

Good stuff Nick. I guess I'll have to use that tank design for artemia
rearing ;)

Thanks for that link, and also Ranger Bob for his link. Some good reading for
lunchtime :)

Have you guys tried the golden pearls products at the Zoo yet for anything?
May be a great solution for all of us in larval fish rearing. I know
cyprinids will take it. The question is whether baby darters will. The
smaller sized stuff (20-80 micron and 60-100 micron) may even be too small ;)
They have sizes then on thru rotifers up to normal sized cichlid pellets. And
these things are *loaded* with protein. Check out this out:

They also have all grades of brine eggs etc. I'm excited to get my system up
so I can start playing with all this next spring :)


-----Original Message-----
From: Nick Zarlinga
Sent: Wednesday, October 02, 2002 12:02 PM
Subject: RE: NANFA-- JellyFish

Casper, the freshwater jelly (Craspedacusta sowerbyi) are really neat
critters. There isn't a bunch of stuff known about them because unlike most
jellies, they spend most of their life in the hydra stage and only a few
weeks (as others have indicated) in the medusa (or "jellyfish") stage. They
are relatively difficult to keep in captivity and the way that most public
aquariums keep jellies is in a bare tank that has rounded corners. There
are two "standard" ways to design a jelly tank: either a Kriesel tank or a
cylinder tank. This is not to say that they can not be kept in other
systems, it is just that since jellies are planktonic, no obstructions is
the best way of keeping them. In both systems, the object is to keep the
animal moving in the current and most importantly to keep it away from and
intakes into the filter (a jet of water blows past the intake screen to keep
the jelly from being sucked onto the screen). A Kriesel tank is basically a
cylinder tank (or an oval shaped tank) that is on its side. It is usually
less than 18 inches from front to back. Also, for other jellies
especially, air lifts are a big no no. Air usually gets trapped under the
bell and can pose serious problems. I do believe that the fw jelly is the
only species found in freshwater, and finding the polyp stage is virtually
impossible. Medusa's usually bloom late in the summer and not every
year-there can be long periods of time when there are no medusa's around.
There have been aquariums that have worked with fw jellies but because they
are so short lived in the "jellyfish" stage, it is very difficult to keep an
exhibit going year round. Check out for more information.
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