[Zbrafish] Mass Embryo Rearing

christian lawrence via zbrafish%40net.bio.net (by clawrence from rics.bwh.harvard.edu)
Thu May 3 12:38:29 EST 2007


We used a similar system to meet considerable daily embryo demands for the
MBL zebrafish course in Woods Hole, MA.

9 liter AHAB tanks, 30-50 fish per tank, with small traps placed in the
corners of the tanks.   Fish spawn through the morning, eggs collected
periodically throughout.

Judy makes an important point about the degree of genetic relatedness
affecting production - we used farm-raised fish from Florida which come from
very large, presumably genetically diverse populations.  SO this is one
reason why production for us was much greater; more on the order of
thousands per tank - if we tried - mostly every day or every other day for 2
weeks.  Spawning activity in tanks much greater in these farm raised fish,
compared with standard lab strains.  We usually had parallel tanks of ABs
that did nothing in these in-tank breeding traps (the behavior simply wasn't
there), but spawned at decent rates in standard out of tank set-ups.   

Some of this is genetic relatedness, and probably also familiarity and
dominance hierarchy buildup.  Keep fish in the same tanks for a long period
of time and watch what happens when the lights come on.  Usually nothing.
But they spawn fine when set up as normal.  However, mix and match them with
other fish and you will see much more spontaneous breeding activity.   In
farm fish, this behavior seems to turned "on" all of the time.  They often
spawn in shipping boxes when you open them up!

Feeding also very important for this kind of production.  Extra feedings are
certainly in order, and live feeds (i.e. enriched Artemia would be best).
Fish at Woods Hole were fed Artemia heavily (3-4X daily) along with a
pellet.

Important point I want to make is that if the research tolerates mixed
genetic backgrounds, the farm fish are the way to go for sheer volume of
embryo production.  Very difficult (but possible) to approach that level in
standard strains.  As long as you are careful when propagating incoming farm
fish stocks, the production (and behavior) will stay through F1-F2 at least.
We have F1 from aquatica tropicals (Dallas Weaver's strain) that breed hard
every morning in tanks from 730am through 11am, even through feedings..


Good luck!
  


Christian Lawrence
Brigham and Women's Hospital
Karp Family Research Laboratories 06-004B
One Blackfan Circle
Boston, Massachusetts 02115
Tel: 617.355.9041
Fax: 617.355.9064

-----Original Message-----
From: zbrafish-bounces from oat.bio.indiana.edu
[mailto:zbrafish-bounces from oat.bio.indiana.edu] On Behalf Of Judy Bennett
Sent: Thursday, May 03, 2007 10:12 AM
To: Doreen; bionet-organisms-zebrafish from moderators.isc.org
Subject: Re: [Zbrafish] Mass Embryo Rearing

Hi Doreen,

I'm assuming you're asking about mass matings to produce embryos....

We use this system with our wild types and it works out very well.

-We have eight 9L tanks (AHAB system), stocked at around 40-50.
-I try to stock a few more females so it's not quite a 1:1 ratio.
-I also try to stock tanks with fish that aren't all siblings, which I
believe increases amount and length of production.
-The tanks are set up once every two weeks starting Monday night, so we have
embryos Tues-Fri (hence the 8 tanks).
-We do have a few "extra" tanks to set up if there is a need for a large
number of embryos.
-The trays we use are homemade, but basically consist of a frame with a
large mesh covering the top and a small mesh covering the bottom.  We
usually attach some artificial grass and insert it at an angle creating a
shallow area.
-These tanks get an extra feeding of dry food (ZIRC recipe) during the week
as well.
-I keep track of the amount laid with a 0-5 scale.  5, being the best, would
mean the tank laid for several hours and produced several hundred/hour.  If
you want 50,000 daily you will probably need to set up more than one of this
type/size tank.
-When a tank starts to decline in production, I stock another tank to
replace it.  I've had a few tanks produce well for over a year, but this can
vary.
-I will use embryos from these mass matings to raise up and replace our WT
stock, but also raise embryos from pair crosses.  Again, since I combine
unrelated fish in these mass mating tanks, and collect eggs throughout the
day/week, I believe this helps avoid inbreeding...(that's another topic in
itself that I think was discussed recently).

-When mutant lines are not producing in pair crosses, I have the lab set
them up in this style and they will lay within one or two times.  (Better
odds of compatible couples?)

I hope this helps and isn't too confusing.  Feel free to ask if you have any
other questions.

Judy Bennett
UMass Amherst
413-577-3457

At 03:34 PM 5/2/07, Doreen wrote:
>I am interested to hear of other facilities experience with the mass 
>raising of wild type embryos.  What worked or didn't work?  Volume and 
>shape of tanks?  Stocking density?  Harvesting method?  Daily egg 
>production achieved?  Method of breeder replacement?  Our current 
>estimate/goal for daily production is 50,000 embryos.
>
>Thank you!
>
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