RE: [Killietalk] Was finding eggs in peat, now finding (catching) fry in peat

["Brian R. Watters" <bwatters at sasktel_net>]

Jim Rae wrote:

>
> Heck with finding the eggs in peat, how do you remove the fry when they
> hatch out?
>

I hatch out my peat spawners (almost exclusively Nothos) in 10x10x4" plastic
trays.The water depth is usually about 3" to 3.5". The thickness of the peat
layer on the bottom will depend to some extent on how much peat there was in
the bag to start with but this is always at least 0.5" (I add extra peat if
necessary).

When I introduce the peat to these hatching trays I stir it up and break up
the lumps to ensure that all eggs have the opportunity to sink. I then skim
off most of the floating peat, the remainder will become saturated and sink
within a day or so.

On hatching, the fry are maintained in the hatching tray for a couple of
days and I am very careful not to overfeed with BBS. Uneaten BBS will get
lodged in the peat, decay and, in my opinion, is the greatest source of
problems with newly hatched Notho fry.

Now, with that information as background to the type of setup I use, how do
I remove the fry from the hatching tray without taking a lot of the peat
with them ?

Basically, I scoop them out using a small margarine tub measuring 3"
diameter by 2" in height. "Scoop" is perhaps not the right word because the
technique I use is to angle the tub and push it down into the water near
where one or more fry are and, as the water rushes into the tub the fry go
in with it. I arrange a light low down, shining into the hatching tray
almost horizontally. The side lighting makes the fry much easier to see.
Vertical lighting will not work nearly as well. The fry will tend to
concentrate around the sides and in the corners of the hatching tray so one
can usually "scoop" a few at once (until the numbers left in the tray become
low). One of the tricks is to remove as little water as possible with each
scoop so that it is possible to remove all the fry before all the water has
been scooped out with them. Margarine tubs are flexible so the rim can be
squeezed and narrowed down for more effective gathering up of the fry in the
corners of the hatching tray and for removing single fry (with a minimum of
water).

It may take a bit of practice but I have been using this method for many,
many years and I can always remove all the fry, regardless of their numbers,
before all the water in the hatching tray has been depleted. In rare cases,
or until one is practiced, it may be necessary to add a bit of water back
into the hatching tray in order to get the last few fry out but, generally,
this will not be necessary.

Some fry may temporarily hide in the peat but if you give them time and rock
the tray gently side to side, they will emerge. Some fry are very dark in
color and may be difficult to see against the peat (especially So. American
annuals) but the side lighting will help with this and it is a problem one
would have regardless of the method used to transfer the fry (other than the
complete immersion methods that have already been described). I don't use
the complete immersion method because: 1. my hatching trays will not fit
into many of my rearing tanks (10 gallon) and, 2. I like to keep the fry in
a relatively small container for the first week or so where they all have
easy access to the food.

This method has numerous advantages:

1. With practice, it is quick and easy.
2. It is less traumatic for the fry (for example, compared with being sucked
up into an eye dropper at a "muzzle velocity" of perhaps in excess of 100
mph).
3. The fry can be transferred together with their hatching water.
___________________________________________
Brian R. Watters
University of Regina
Regina, Sask. S4S 0A2, Canada
Ph: (306) 584-9161 (home); (306) 585-4663 (work)
Fax: (306) 585-5433
E-mail: bwatters at sasktel_net



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