Freshwater Invertebrates

Our school purchased a 55-gallon "natural aquarium ecosystem" ... with
newts, frogs, fish, live plants, etc ... The fish include swordtails, two
types of guppies, kullie loaches, clown loaches, & silver dollars. In
addition to the main tank, there is an attached "swamp" that *should* be
devoid of fish - just plants, invertebrates, protists, etc ... I'm trying
to incorporate the tank into my classes - doing water quality testing
regularly with my chemistry students and encouraging the biology teachers to
use it also!

I took my class to a local river last fall and did some sampling - we added
several invertebrates from the river to the aquarium tank, including a
damselfly nymph that eventually transformed into a full-grown damselfly
within the aquarium! There were about 8 small crayfish ... but lately I see
only one or two large survivors. I assume that when they molt they are
vulnerable to the other crayfish. The swamp is teaming with hydra, some
copepods living tubifex worms, planaria, and daphnia. There are also two
species of snails in there. The back of the aquarium has rocks that are
above water, with live moss and other plants growing there. We've got
crickets and mealworms living above water - although the crickets have a
gift for jumping into the water and drowning where they then decompose or
become food for the newts and frogs.

The guy who builds these and sold us one has got me going with this. We're
now trying to culture the daphnia, along with mealworms and possibly some
algae. I'm thinking of devoting a 2nd 30-gallon tank just to plants and
invertebrates.

Mike

"NetMax" wrote in message
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"dfreas" wrote in message
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We talk all of the time about fish and plants and water chemistry but
it seems like freshwater invertebrates rarely come up except in the
context of "how do I get rid of these things?" However I have been
keeping a number of invertebrates for a while now and I think they
really do improve the quality of my tanks - both visually and
chemically. I'd like to see what experiences others have in this area
and ask a few specific questions.

We all know pretty much all we need to know about freshwater snails. I
keep three varieties in my tanks - ramshorn, pond, and trumpet. They
aren't picky and proliferate excessively in any water conditions that
don't include copper. So if you have something interesting to add about
these little guys then by all means do so but for now I'll move on to
more interesting specimens.

Lumbriculus variegatus is an interesting choice. These are the
blackworms that many of us use as live food. But try feeding an
excessive amount of them once or twice - your fish won't be able to eat
them all and many will escape into the substrate to live out their
lives. You'll see them poke their tails up above the substrate whenever
predators aren't around in order to get better oxygen flow over their
bodies. If you have them in a fishless tank you'll even get to see them
swim in a very cool double helical pattern. I love these guys because I
have a self sustaining colony of them and they are a huge help when I'm
adding a new fish. During any new arrival's adjustment period they have
a natural live food snack to hunt for while adjusting to my normal
feeding schedule. Also the black worms help break down decaying matter
in the substrate into a form that the plants can use - the perfect
missing link than many aquariums need! They are also a favorite snack
of ghost shrimp.

Which brings us to another great invert. Shrimp. I keep ghost shrimp
and often see the females carrying eggs but alas the babies never grow
to adulthood. I suspect they get eaten by the fish and other shrimp in
the tank. Has anyone had success breeding shrmip in a community tank?
If so what kind of shrimp and how? At any rate these are another
wonderful substrate cleaner - any dropped food or bits of garbage will
quickly be collected and broken down by most shrimp.

The invert that I'm most interested in at the moment would be the
bivalves. I have half a dozen golden clams in my tank but this is
hardly enough to satisfy me. All of my other invert populations are
constantly reproducing except these guys. Has anyone had any success at
all with getting a freshwater bivalve of any type to reproduce in
normal aquarium settings? I'm hesitant to collect local specimens as I
suspect they are used to a much higher oxygen content than I can
provide from cold waters and fast running rivers. I may try it
eventually but for now I'm learning all that I can about them before
giving it a shot. I've kept golden clams for a while now with some
success, they seem happy and I watch them dig and move around
occasionally, mostly they just sit still and filter. Half a dozen of
them aren't enough to make much of a difference in the water quality
but I suspect if I could get a self sustaining colony of bivalves a
population explosion would quickly do some impressive things. Anyone
with bivalve breeding experience please speak up!

And of course there is always the occasional millimeter long worm
inching it's way across the aquarium glass or a tiny hydra attached to
a rock. These are interesting but nearly impossible to keep in any
large quantities since they seem to be prime food for small fish. Of
course I'm not even sure I would want to keep them in large quantities
- I like seeing them occasionaly but I don't think that I would like to
see them bloom.

My quest for the most natural aquarium I can achieve marches on and I
would like to hear the experiences of everyone else who has kept
invertibrates in large numbers. IMHO these guys are improving water
quality and tank interest immensly, they truly are the difference
between a tank full of fish and a tank exploding with natural life.

-Daniel


I enjoyed your post. I can't add much to your questions, as my level of
experience with bivalves, shrimp and worms is at about the same level as
yourself. However I've found that one of the keys to keeping inverts is a
predator-free (no fish) feeding area.

To this end, I've had some success with Echinodorous tenellus (think of a
miniature chain straight-leaf corkscrew) covering a wide area of the
substrate, so the inverts could wander around with some protection. The
tenellus needs to be thickly planted (which it'll do on its own,
eventually).

Sunset hygro has worked even better, but this one tries to grow
vertically, so you need to push the new growths back into the substrate.
With enough 'training' it's not too difficult to get the hygro to cover
your substrate, and the leaves then form a canopy about 2-1/2" above the
substrate, more than enough room for inverts to wander around unmolested.
It's a pleasant sight to see the fish swimming a few inches above the
invertebrates, almost like getting two aquariums for the price of one ;~).
hth
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