How
many hobbyists have started with a community tank? I would venture
to say most, if not nearly all. I know I did. In that community
tank we crammed fish with nothing in common from all over the world,
and added some Corydoras catfish as “scavengers”
to clean up all our mistakes. Usually, until quite recently, that
Cory was probably Corydoras aeneus, the Bronze Cory. Bronze
Corys were a mainstay, a “bread and butter” fish, from
the time of their introduction until just a year or two ago.
The Bronze Cory was introduced to science in 1858 with the name
Hoplosoma aeneus. Gill (a fitting name for an icthyologist!)
described it from a collection on the Caribbean island of Trinidad.
Later it was found all over Venezuela and even reported as far south
as Bolivia! Dr. Axelrod recently reported it from the Pantanal in
Brazil, as well (TFH, Mar 1993) thought it may be a “look
alike” species. In the late 1800’s the Bronze Cory was
moved to the genus Corydoras where it remains to this day.
The name Corydoras means helmeted doras (Doras
is another catfish genus) and aeneus means bronze.
Bronze Corys came to the hobby in the early 1900’s through
the efforts of German importers like Herr Schnelle of Aquarium Hamburg.
One of his boats had a port of call at Port-of-Spain, Trinidad,
where local collectors had easy access to C. aeneus. Since
it can utilize its gut to absorb oxygen from atmospheric air, it
was perfectly suited to survive the long trip across the Atlantic
in the relatively cramped quarters of the time fish were shipped
in at the time. Once established in Germany, aquarists found C.aeneus
easy to breed and began to produce them in quantity.
These early captive bred C.aeneus, along with wild imports
from Trinidad, found their way to New York in 1933, and from there
to hobbyists all around the U.S.
Although small in size, Corys are true catfish. They belong to the
catfish family Callischthyidae, the Armored Catfish. They
are bottom dwelling (except for a few dwarf species), and have downward
pointing mouths surrounded by barbells covered with taste buds.
They use these to search out food in the murky waters they call
home. They are naked – they have no scales. They are covered
with bony plates called Scutes. They have spines in the dorsal and
pectoral fins. These spines can easily be caught in coarse nets,
so corys should be netted with fine mesh to avoid damaging their
fins.
Corys have the habit of suddenly darting to the surface and gulping
air, and then returning to the bottom. They sit still for a moment
and then seem to wink at you. What they are actually doing is forcing
the air into their gut where the oxygen will be extracted. Since
corys live in murky water with a muddy bottom in the wild, local
fishermen watch for surfacing to indicate where a school of corys
may be. They then set up their seines to try and catch the school.
Since corys are so easy to spot, many countries limit fishermen
to one sweep of the seine per area, to enable the wild population
to maintain itself.
In the aquarium trade, corys are sold as “scavengers”
or worker fish, which will “clean up after other fish and
cover up the aquarists’ mistakes”. Nothing could be
further from the truth! Corys are interesting fish in their own
right, and deserve better than the table scraps of other fish. Feed
them sinking pelleted food such as Brine Shrimp pellets, Tabi Min
by Tetra, Hikari Sinking Wafers for Catfish (excellent!) and Trout
Chow. They will also eat a variety of frozen foods, worms of all
descriptions, and live baby brine shrimp. If you want to breed them,
feed them heavily two or more times a day.
Sexing Corydoras aeneus is best done from the top. When
breeding it is best to use at least a reverse trio (2 males and
1 female) or a group of several adults of both sexes. To encourage
corys to spawn, separate the sexes and feed heavily for a week or
so in warm water (80 F+). Put the corys together in a 10-15 gallon
tank with slightly cooler water than they are used to. 2 F to 5
F cooler should be enough. PH and hardness are no longer important
to “domesticated” for so many generations under varying
water conditions. My water is about 8.5 ph and 450ppm total hardness,
and they spawn for me fairly regularly. Add a sponge filter and
a few broad-leafed plastic or live plants and let them go.
The spawning act can be divided, like a play, into three main acts:
Act 1: The Chase. This act consists of chasing all over the tank
at all levels, up the glass, through the plants, everywhere. This
act can last from a few minutes to several hours, but usually is
over in an hour or two.
Act 2: The Cleaning. In this act the players begin to clean everything
that has potential as a breeding site. This includes the undersides
of plant leaves, and the glass itself. This act lasts for a half
hour to a couple of hours or so.
Act 3: The Spawning. In this final act, the play reaches its climax,
and the players begin the serious business of reproduction. This
act, once started, is difficult to interrupt short of physically
separating the fish. The females nudge the males in the belly, triggering
the release of sperm, (the Famous T-Position), and simultaneously
the female releases from 1-4 eggs into supped pelvic fins, where
they are fertilized. She then rushes off and deposits the eggs in
a previously cleaned spot, or cleans a new one and puts them there.
Several authorities for years debated whether or not the female
took the sperm in her mouth and put it on the spot where the eggs
were then pressed, but now most experts agree that this does not
happen. Sometimes the female “forgets” to clean a spot,
and if she did not smear the sperm there first, these eggs would
be infertile, but they are not. Once Act 3 is finished, and the
breeders seem to be resting, or searching for food, remove the eggs.
C.aeneus is an avid egg eater. Many texts claim they will
touch neither eggs nor fry, but I have found this to be false. The
eggs are easily removed by gently rolling them onto your finger
or scraping them off with a razor blade. Hold the blade very close
to the glass or you will damage them. The eggs are sticky, and it
takes some practice to get them off your finger into the container,
but it gets easier when you work out a method, Fortunately, C.
aeneus lays 200-300 eggs at a time! These eggs will hatch out
in 2 or 3 days.
Many people advocate sterile conditions while spawning fish, and
for some species this is necessary, but for c.aeneus it
is deadly. While the fry do require regular water changes as with
all fish, newly hatched cory fry seem to need to disappear in to
the “mulm” at the bottom of the tank. They will disappear
for several days before making an appearance, at which time they
are miniature copies of their parents. Without this mulm, your chances
of raising a large batch are somewhat limited. Young corys will
eat all kinds of “goodies” in the mulm, as well as microworms,
baby brine, and finely crushed flake food. If you have a shortage
of mulm, both Sallie Boggs and Ginny Eckstein recommend “sponge
grunge” which is basically the gunk you usually get rid of
when you clean your sponge filters. Take a couple of really dirty
sponge filters and wring them out into the fry tank. The brown gunk
is the sponge grunge you want! Really! Both of these ladies have
raised a lot of corys and it works for them. Dr. William T. Innes,
in Exotic Aquarium Fisher recommends a layer of mulm up to 1/2 inch
deep! You can’t argue with success, it works!
When the fry are about 3/4 of an inch, you can start parting with
them. By this time they should be eating the same food you are feeding
their parents, and they are ready to join them. Don’t forget
that corys like to school and for this should have a group of at
least six individuals. Just to mentions, since the parents are CATfish,
I suppose we should call the fry “kittens”!
I entitled this article Corydoras aeneus, the Forgotten
Cory? For a reason. I have noticed over the past 12 to 24 months
that Bronze Corys have all but disappeared from local shops; at
the same time many “new” fancy species have put in an
appearance. I guess “simple” Bronze Corys don’t
have the market appeal of Corydoras spotyusfrillyous. Bronze
Corys have been around a long time, are tank raised, and domesticated
so that they spawn seemingly on command after a water change, and
live for a long time. I personally had five Bronze Corys I bought
at Bennets in 1978 and sold at an auction in 1989, still going strong
and spawning on occasion! For a dash of color, there is an albino
strain which develops a greenish blue face at maturity. Tried and
true and still going strong, if you can find them and want to breed
catfish, try Corydoras aeneus, the Bronze Cory, first!
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