Re: NANFA-- Diving Spiders

Bohlen (
Fri, 11 Feb 2000 19:46:35 +0100

Some time ago I used to have the two native (in Europe) species of fishing
spiders (Dolomedes fimbriatus and D. plantarius) in aquaria. They are such
fascinating and beautiful animals and make up phanstastic pets! You can
easily keep them in a half-filled aquarium of 60 cm length with vegetation
growing above water line and a small terrestrial part (floating styrofoam).
It should be possible to keep them in shorter tanks, but than you will
hardly see the behaviour (hunting and escape, different types of nest
constructing etc.) to it's full extent. They live not directly on the water,
but most love most to have four legs on a solid substrate and four on the
water. I used tanks in which I reared up newts or Elassoma, because these
are close to bottom or within dense vegetation, so no "accident" between
spider and fish happens. The spiders do not regularly feed from below the
surface. I have several times tried to feed the spiders with baby guppy or
Epiplatis (I read they are "fish-killers"), but as hard they tried, they
only rarely got a fish (if guppies were more than one day in that tank, they
were too experienced to be caugth anymore). That is different if the food is
on the surface or on the close land: the spiders are fast and efficient
hunters, but a little greedy. The last is why you can only have one spider
per tank. And therefore it needs some patient to mate them. If you place a
male into the females tank, it usually is one of the last things the males
experiences in his live, the only question is, if the female allows him to
place his pedipalpus before biting. On the other hand, the females is a
loving mother, carrying the cocoon with the eggs with their cheliceras
(which means she can't eat during weeks). Since fishing spiders are
sun-loving creatures, an electric bulb above the water, shining 2 h in the
morning and 2 in the evening, is first-class accomodation. Such bulb at
least is necessary to enshure successful development of the eggs and young.
The cocoonn is placed by the mother into a special net, in which all baby
spiders live for some days (until next mount), than go their own ways.

In comparison, the underwater spider, Argyrineta aquatica, is quite boring.
It is a secret animal, which lives in the very dense vegetation and does not
like to act out of such shelter. You can have several in one tank, even
together with non-prdatorous fish (up to one per two litres in densely
vegetated tanks; tanks from 20 cm onward are sufficient) and they even
reproduce in that tank. You see just some air "castles" and sometimes a
spider stalking through the vegetation. But this surely is a question of
keeping conditions and the enthusiasm of the viewer.

Anyhow, I like this spiders, and instead of killing them at your pond, you
may take it a while and see one more fascinating animal.


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