zebrafish questions


Wed Aug 11 03:08:00 EST 2004


in article cep3vj$6ni$1 at mercury.rfcgr.mrc.ac.uk, Sivaraman, Lakshmi at
lakshmi.sivaraman at pharmacia.com wrote on 8/3/04 3:35 PM:

> --------------------------------------------------------------------------
>
> I am new to the zebrafish field.  I am in the process of setting up some
fish tanks in my lab.
>
> I have the following questions regarding this:
>
> 1.  How do you control the growth of algae in these tanks?  My tanks are
fitted with a mechanical, chemical (carbon) and biological (bio-wheel)
filter

The primary method for controlling algae is decrease the light level.  The
fish don't need much light.  Even with lots of water flushes, you will
still have enough nutrients to grow significant amounts of algae at high
light levels.

The fish actually would prefer some algae on the walls, you just want then
clean so you can see the fish.  There are some blue green species that can
create problems, but most of the green algae are beneficial.
>
> 2.  How often do you need to clean out these tanks completely?

In a well balanced system, where your microbiological ecology is doing
it's decomposition job, the only reason to clean a tank is for human
esthetics. The zebra fish really only care about water chemistry, not
water color or turbidity.

You can also use snails (get pathogen free snails) to clean algae and the
bottom.

Always keep in mind that a working recycle fish system depends upon it's
microbiological ecology and if that ecology is doing well, your fish will
probably be doing well.  You will have almost as much microbiological
biomass in the system as you will have fish biomass.  Remember, only about
20% or so (with very good quality feeds) of the dry wt of the feed ends up
as living fish tissue with the rest being metabolized by the fish and the
microbiological ecology, finally ending up as stable sludge, CO2, H2O,
NO3--.  It is dealing with that 80% of that feed input which keeps us
Aquaculture Engineers busy consulting around the world.


>
> 3.  What is the alternate method of collecting embryos besides using
marbles at the bottom of the tank?

I use spawning trays and don't separate my sexes.
>
> 4.  Since males and females are housed separately (though I have problem
identifying males and females clearly) is bringing them together 24h
before collections of eggs enough time for them to breed?
>
> 5.  Do you need to feed the fish before collecting the eggs that morning
or that can wait till after collection?

Not necessary and will add contamination to the eggs.
>
> Thanks much for all the help.  Any suggestions are welcome to make my
entry into this field smooth.

Temperature question on another posting.

The 28.5º C standard is arbitrary.  This species of fish will spawn
between 19ºC and 29ºC , between a pH of 5.75 and 7.8, and between
salinities of 300 to 3000 ppm (TDS) -- range known from personal
experience.  I feel that the advantages of 24 to 25ºC in terms of staff
moral and focus more than compensates for any minor advantage of operating
at 28ºC.  Most zebra fish researchers squander the minor temperature
growth rate advantage by using poor or low quality diets (poor quality
diets at high temperatures will actually decrease growth rate relative to
lower temperatures).   With good diets and good water quality, you can go
from egg to egg in 47 days (pf) at 28ºC, but you can still do less than 70
days (pf) at high density (> 50/liter) at 23 to 24ºC.

>
> Regards,
>
> Lakshmi Sivaraman
> Principal Scientist
> World Wide Safety Sciences
> Pfizer Global Research & Development, 0216-300-425.2
> 7000 Portage Road, Kalamazoo, MI 49001
> Phone: 269-833-8305  Fax: 269-833-7722
> lakshmi.sivaraman at pfizer.com
>
>
Any more husbandry question, contact me.

Dallas
-- 
Dallas E. Weaver, Ph.D.
Scientific Hatcheries
5542 Engineer Dr.
Huntington Beach, Ca 92649
deweaver at surfcity.net
http://www.ScientificHatcheries.com



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