John Knowles j.f.knowles at clara.co.uk
Thu Jun 3 18:38:24 EST 1999


The following is a request for your help and opinion on the use of
Zebrafish in some planned experiments. It has ended up longer than
intended, I can only apologise and ask for your forbearance.

I'm a research scientist at The Centre for the Environment,  Fisheries
and Aquaculture Science, Lowestoft Laboratory, Pakefield Road,
Lowestoft, Suffolk, NR33 0HT UK. (or CEFAS. It's a government agency).
I'm a radiobiologist  concerned with examining the possible
damage to aquatic organisms by caused by long term exposures to
radiation at the relatively low levels resulting from authorised
disposals radioactive wastes.  While there are some drawbacks to using
tropical fish (try bathing in river or sea in England any months except
July-September, no tropical fish would) they have many advantages as lab
animals ( I presume I am speaking to the converted) and in the past we
have exposed guppies for periods of over a year and examined effects on
reproductive output. Unfortunately on trying to repeat these
experiments to compare alpha- and gamma- radiations we've had enormous
problems with guppies, probably because of poor stock. Basically they
die a lot and we can't put it down to our husbandry etc. (believe me
we've checked everything we can think of).  We've had some Zebrafish in
the lab for a couple of months and they have survived very well (no
deaths at all) and think it may be a good idea to use these instead.
Although we used guppies because they are live-bearers and we can
ascertain output in terms of numbers of viable young born per pair
(fertility, fecundity), interbrood period etc, there seems to be no
reason why we can't look at reproductive output in zebrafish.  It seems
we'll have to have groups of fish rather than  pairs from what I have
read, but the large numbers of eggs laid offer good
statistics and the possibility of measuring egg development seem a
possible advantage.  The proposed experiment would expose zebars to
alpha radiation via their food (spiked artemia)  aooor gamma radiation
(via an external source) from a very young age and examine the output
of eggs, their survival etc. over a period of a year or so.  Does this
sound feasible?

The other thing I would like to ask is can we sex zebras at a young
age?  We want to make up our groups and then irradiate them from a young
age and if by chance we have all one sex in a group it would be a
hindrance (although we can rearrange groups as soon as we can sex them).

Yours sincerely, John Knowles
email  j.f.knowles at cefas.co.uk

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