NANFA-- Outdoor Systems vs Indoor Systems

Mark (
Fri, 21 May 2004 21:24:52 -0400

I imagine others have noticed that fishes raised in outdoor
containers/ponds often thrive better and are easier to care for than
fishes raised indoors. I think this has a lot to do with the larger
volumes of water used in outdoor containers, but also to do with the
free insect and invertebrate feed they get outdoors. But I'm also
wondering to what extent the sunlight and increased organic matter
have on the bottom of the food chain -- bacteria, protozoa and algae
which would also feed the next level of the food chain -- the
insects, crustaceans, etc, which feed the fishes. Can this benefit
only be derived in an outdoor system? Or would it be possible to
replicate this indoors with full spectrum, high intensity lights,
proper substrates and filtration adjustments (refugia)? Kind of like
a freshwater "reef" system, in which you would try to reproduce a
larger portion of the food web and nutrient cycling than just
efficiently moving fish food in and waste products out. I think
there have been some threads on the list along these lines, though I
didn't follow them. What did I miss? Anything good? I would be very
interested to hear ideas about the whole concept. Is the lighting
critical, or can you create a more complete ecosystem in a low light
environment? Seems like light would be needed for many kinds of
photosythesizing microbes, but are they really indispensible in a
food web that can support fishes from scratch? Someone needs to do
some research on this and write it up for AC or elsewhere. Here's an
observation on my experience outdoors this year: I put out a tub
(20-30 gal) last year with some killies in it. I left it out all
winter. The killies spawned, but died in the cold and ice. But this
spring the thing was full of inverts including bloodworms, mosquitoes
and glass worms. I put some banded sunfish in there and they fed
well on the critters. I think leaving it out all year made for a
more complex and productive "system", if a stagnant tub of water is a
system! Now I'm thinking of putting out several tubs and moving the
fish from one to the next with a break in between for feed critters
to grow.

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