Re: [Killietalk] K. marmoratus habitats, etc./2

[Pablo Robles <roblepl at gmail_com>]

Thank you so much for sharing your knowledge Bruce.

I will certainly adapt some of these techniques to my fish room. I would 
later document the final setup and results back to killietalk. I plan on 
using one gallon plastic critter keeper tanks with some plastic mesh I 
have laying around somewhere. Will separate the two fish just to be safe.

hasta pronto,

Pablo

Bruce J. Turner, Dept. Biol. Sci., VPISU, Blacksburg, VA 240 wrote:
> To answer Pablo's quesions as best I can:
>
>
> 1. We breed kmar in glass "fingerbowls" about 10 cm wide and about 5 cm high.
> These bowls are stackable, and we keep them in stacks up to 12 - 14 bowls high.
> A single "herm" is placed in each bowl.  I haven't checked on a commercial
> source for these bowls in quite some time (since I own literally hundreds), but
> I believe we purchased them from Carolina Biological Supply Co.  Aquarists,
> including killifish specialists, who see this arrangement are usually appalled
> and sometimes speechless; it is designed for efficiency, not for optimal
> viewing of the fish.
>
>      The "false bottom" is a disk of rigid plastic screen with holes about 3 - 4
> mm
> in diameter.  The screen fits the inside diameter of the glass bowl rather
> snugly, so that the herm cannot get below the screen into the bottom chamber.
> The screen is set off the bottom by spacers.  Originally, these were glass
> "marbles" fixed to the bottom of the bowl by gluing with silicone cement.
> Subsequently, I switched to using the top (straight) halves of 1.5 ml
> disposable plastic microcentrifuge tubes.   Some of my colleagues use a glass
> ring instead.  Obviously, many different types of spacers can be used.  When in
> place
> as a "false bottom," the screen, sitting on its spacers, establishes a bottom
> chamber about 1 cm high.  The eggs are collected from this chamber by removing
> the herm and the screen once a week, and then picking out the eggs with a
> plastic eye dropper. It is at this time that the water is changed, completely.
>
>     The design has the obvious disadvantage of allowing uneaten food and feces
> to pass through the screen also, and often the eggs are mixed with these in the
> bottom chamber. Its advantages are that the eggs, once spawned, quickly fall
> beyond the reach of the herm, who will otherwise eat them.  The eggs aren't
> very adhesive (which is one of the reasons why mops don't work very well).
> When housed in setups like this, herms usually spawn one egg at a time.
> Sometimes, a herm will express a mass of up to 70 - 80 eggs (though usually
> around 10), seemingly simultaneously.  When these masses are expressed, many of
> the eggs cling to the vent area of the herm, rather like medaka eggs.  They are
> eventually sloughed
> off. If housed in groups, other herms will go after the attached eggs much as a
> thirsty man might attack a large bowl of grapes!
>
>  BTW, when spawning eggs, some herms seem to twist their bodies as if they
> were in a spawning embrace with a male, while others just pop them out, willy
> nilly, with no obvious preliminaries.  Also when viewing stacks of bowls, each
> containing a herm, very often one doesn't actually see fish, particularly in
> the mornings.  This is because the fish are resting, out of the water, on the
> underside of the bowl stacked above them.  A smart smack on the top of the
> stack usually results in all the fish dropping off their ceilings into the
> water.
>
>      I expect that most aquarists will not want to use the bowls, but the false
> bottom idea can be adapted to almost any type of spawning chamber or tank that
> one likes.  It is designed for herms living alone and is less effective if
> multiple herms are housed together (for obvious reasons).
>
> 2.  We incubate the eggs in sea water in 7 cm diameter plastic petri dishes.
> Some labs use only glass petri dishes. Usually, we use just enough sea water to
> cover the eggs, leaving a "head" of a mm or so.  We incubate them in the dark at
> about 24 C (the ambient temperature of the fish room).   Infertile eggs are
> obvious within a day or two, and are
> removed.  Subsequent mortality of embryos under most conditions is about 15 to
> 25$%, but 50% has been noted in some cases.  Diapause at the end of development
> is sometimes a problem, particularly if the incubation temperature is too low
> (20 C or less). In my lab, problems with diapause are episodic, and we can go
> long periods without it bothering us too much. When it does become an issue, we
> have used several methods to break it, including the usual ones like adding dry
> food or microworms to the water, moving the embryos to half sea water, adding
> peat extract, etc.  The most
> effective method I've found is to seal the petri dish with scotch tape and have
> someone take it for a ride on a motorcycle for about half a mile or so.  A car
> with bad shock absorbers probably would work almost as well.  In recent years,
> I have used manual dechorionation on stubborn embryos, but it takes practice
> and a steady hand, and I doubt that many aquarists will want to try it.
>
> 3.  The fry are very easy to raise.  We keep newly hatched fry together for
> about a week, and then usually move them to individual plastic containers for
> further rearing.  They are very cannibalistic, and the slightest size
> difference usually mean that the larger fry makes a meal out of the smaller
> ones.  We feed Artemia nauplii almost exclusively, even to adult fish (I know
> this is killifish "heresy," but there it is.)  The advantage of Artemia is an
> obvious one: they stay alive in sea water until they are eaten (which isn't
> usually a very long period---these are not fish with delicate appetites).  Even
> so, water needs to be changed frequently in the small containers we
> use---generally about once a week.
>
> Our lab has had, at some peak periods, as many as 1400 fish, most housed
> individually.  We have had up to about 400 herms as breeders in individual
> bowls.  Obviously,this entails having technicians available to feed, monitor
> eggs, change water, etc.  At the moment, we have fewer than 400 fish, and I'm
> phasing out the live fish colony as preparation for closing down the fishroom.
> I will retire in less than 4 years, and I want to have ample time to give our
> fish to colleagues, etc. before I do so. I expect that the fish room will be
> closed down by June 08.
>
> The setup that Pablo is using will probably work well for two herms, in the
> sense that they will have enough room to avoid one another a bit.  I would
> increase the tank size to 20 or even 40 l.  When I house multiple herms in the
> same tank, I put 10 - 15 7 - 8 cm long pieces of 1/2 inch pvc pipe on the
> bottom to provide hiding places.  When they become aggressive, the herms will
> literally chase one another through the pipes.  Above all, SEAL THE TANK.  Like
> other "Rivulus," kmar herms and males can find the smallest crack by which to
> escape.  Remember that leaving the water is one of the things they do best, and
> that they can live, packed in moist leaves, for at least 60 days.  If you find
> a kmar shriveled on the floor, do not presume that it is dead.  Put it in sea
> water---often you will have a "miracle."
>
> Please note that many of these culture methods were developed by my colleague,
> W.P. Davis.  While at the Univ. of Guelph, my colleague David Noakes
> independently developed very similar methods. Also, most of the field
> observations mentioned in my last post were initially made by Scott Taylor
> and/or W.P. Davis.  Most often, I was just "along for the ride," generally with
> my mouth agape in astonishment.
>
>
>
>
> Bruce J. Turner
> Dept. Biol. Sci.
> VIRGINIA TECH
> Blacksburg, VA 24061
> (540)-231-7444 (V)
>                       "...We are Hokies.  We will prevail..."
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>   

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