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Fwd: Volvox as fry food
- To: live-foods at actwin_com
- Subject: Fwd: Volvox as fry food
- From: "David W. Webb" <dwebb at ti_com>
- Date: Tue, 5 Aug 1997 09:44:16 -0500
- Conversation-Id: <199708050236.WAA09011 at acme_actwin.com>
- In-Reply-To: <199708050236.WAA09011 at acme_actwin.com>
Mark is not a member of the list as of this submission, so he will not see
any responses to the list. Please direct any correspondence to him as well
if you want him to see it.
BTW, I found this post very interesting.
Forwarded message follows:
From: "Mark O'Connor" <marko at Canberra_teknet.net.au>
Subject: Volvox as fry food
The following is a message I have just put on the AUNZZA (Southern
Hemisphere killifish) network, and may also be of interest to your members.
As I'm very short of time, I'm not sure if I can extend the offer made in
it to distribute my local strain of volvox to all who might want to
experiment with it, and there may be problems with mailing it abroad from
Australia. But there are strains of volvox everywhere, and the ideas in
this piece should be of great interest to livefood enthusiasts.
--A NOTE ON A MOST PROMISING LIVE FOOD.
Volvox is a giant infusorian. It is a slow-swimming colonial
algae, but vastly larger than those mobile algae species like
Euglena that are found in ordinary "green water". Adult individ-
uals or colonies are visible to the naked eye (against a fairly
good light) as green or pale green globules, almost perfectly
round. Adults of the species I am offering to spread around are
about the size of brine shrimp, but a culture will also contain
juveniles of a size suitable to feed very small egg-layer fry.
Their lack of projections and the fact that they do not thrash
around like microworms or vinegar eels are added advantages. The
fact that they move slowly to the light enables them to be bred
in a vat and concentrated for use.
The Encyclopaedia of Live Foods says they are found in iron-rich
waters, usually under a layer of duckweed (i.e. not in in full
sunlight) and that they can co-exist with daphnia. It comments
that during the season when they swarm "fish fry grow fat".
Presumably this refers to European or North American species.
My culture, which thins out or disappears in summer, has re-
appeared for the last three winters as a dense culture in a broad
1-gallon (5 litre) glass sweets-jar left out against the North
wall of my house. (There is a half teaspoon of salt in the water
to make it less likely to freeze and crack the jar, though the
top does freeze fairly often). I added some chelated iron after
identifying the culture, and the odd drop of aquarium plant
fertiliser since. There is a thick layer of azolla and duckweed
on top, and the jar is heavily shaded from overhead sun, but
takes in quite a lot of direct but slanting light through its
sides especially in winter. Perhaps less crucial than the shading
is the fact that as the azolla and duckweed multiply there is a
slow but steady suppy of drowned plants which can no longer find
room at the surface. Their decay also feeds a population of
tubifex at the bottom of the jar, and no doubt releases nutri-
ents. Last summer daphnia and cyclops re-appeared and seemed to
eliminate the volvox, but it re-appeared recently as a fairly
Not much is known about this Australian (?) species of volvox. I
would urge fish breeders to experiment with pipetting off a pure
culture and experimenting to find the temperature and light
intensity in which it can best be cultivated. (Windowsill cul-
tures, which get steadier temperatures, don't seem to work so
well, though this may be simply because cyclops etc are able to
I believe volvox has great potential as a trouble-free permanent
fry food. If cultivated in bulk, it might also be ideal food for
young live-bearers. If it can be cultivated alongside ordinary
"green water" the result might be a "one-stop" fry food for
egglayers of all ages. I also wonder whether it might not enable
discus fry to be artificially reared without troublesome egg-
I can supply a small vial of this strain of Volvox to any aquar-
ist genuinely interested in cultivating them (for $5 including
I would also encourage people to experiment with their local
strains of volvox. (There are some much larger species around in
SE Australia, but to date I have been unable to cultivate them).
8 Banjine St O'Connor ACT 2602 Australia
ph. 61 6 247 3341
Fax 06 249 0102 c/- Mrs Jan O'Connor
David W. Webb Texas Instruments
(972) 575-3443 (voice) http://www.dallas.net/~dwebb
(214) 581-2380 (pager) 2145812380 at alphapage_airtouch.com