"I wish I had a pencil thin mustache"
Spawning Corydoras adolfoi
By Dave Lorbeske
From Splash, newsletter of the Milwaukee Aquarium Society
Aquarticles.com
Although I’ve kept tropical fish in community tanks off and on over the years
(more off than on) my interest was rekindled last year by my 20-year-old son, Dan.
He’s responsible for the fish aisle at the Animal Crackers on South 76th Street and
Grange in Greendale. A friend and co-worker of Dan’s gave me a 35-gallon aquarium he
wasn’t using. About $200 later my "free" aquarium was setup and filled with
rainbow fish and Corydoras. Dan and I were fascinated by the wide variety of corys
available and liked the beautiful gold crowned Corydoras adolfoi best. So, not
being the sharpest knife in the drawer, and having never bred a fish before, I decided
that we’d give the adolfoi a shot.
Initially, we got a lot of good advice from Gary Greenwood at Pets ’N Things.
He’s spawned a number of corys and is always willing to take the time to help. He
also recommended the Milwaukee Aquarium Society to me. Thanks primarily to information
learned from Gary; Bob Schneider of Chicago’s Green Water Aquarium Society, who spoke
about breeding Corydoras at the first meeting I attended; and Milwaukee members Dan Cram
and Iggie Balistrieri we have been successful. Our thanks to all of them.
It took several months to get our initial group of young adolfoi big, buff, and
breedable. They are fed a variety of frozen foods including brine shrimp, bloodworms, and
community menu. Brine shrimp pellets and sinking tablets are also offered. The catfish
were impossible to sex until they matured. The females are wider, have a thicker
silhouette, and are a little bigger overall.
Although the adolfoi started spawning last December our detailed daily data for the
month is lost. Actually, it’s been recycled. (A technical aside - don’t keep
spawning records on the family’s important dates/appointments wall calendar,
especially during December. It went out with the old year. This year we keep our own
calendar next to the aquariums. We have our data but I missed an anniversary. No system is
perfect it seems.)
During January and February our 12 breeders, four females and eight males, spawned on
28 different days. Between three and 37 eggs were laid each time, depending on how many
females were active. The average was 12 eggs. Spawning usually occurred on several
consecutive days. And fellas, playing your cards right on Valentine’s Day gets
results. The adolfoi only bred five times in February before cupid came on the 14th and 10
times after!
Our parent catfish are kept in a 20-gallon high aquarium where we try to replicate the
spring rainy season spawning conditions of the adolfoi’s home waters, the tributaries
of the upper Rio Negro in Brazil. The tank has several inches of gravel, a piece of
driftwood, two plastic Amazon sword plants, a submersible heater, an air stone, a Penguin
550 power head, and a Millennium 3000 double filter. The water level is maintained at four
to five inches below the tank top so that the two filter outputs create twin waterfalls,
lots of bubbles and movement. The power head provides horizontal current and as far as the
fish are concerned a river. Water depth is about eight inches. The temperature is kept at
slightly above 70 degrees because the spring rains that help spark spawning in the Rio
Negro cool the water. Other than the addition of driftwood, nothing is done to alter the
water chemistry. The pH is 7.4. We also have 10 younger and smaller adolfoi in an
identical 20-gallon setup. They, too, have begun spawning.
Breeding always occurs in the late afternoon and evening and usually lasts several
hours. Outside barometric pressure changes associated with frontal passages affect the
fish. Those changes, coupled with the cool, moving water trigger activity. A water change
dropping the temperature another degree or two also helps. Although the technique
doesn’t work for me personally, pouring cold water on a catfish results in romance.
It begins with restless activity as the school swims around the aquarium. Soon several
males dart around, below and above a female, mouthing the top of her head and vying for
position in front of her. Eventually, one of the males makes all the right moves, the
female makes her selection and the pair assumes the "T" position. They drop to
the bottom of the tank as the male rolls over on his side in front of the female. With his
bottom toward the female he forms the top of the "T." His upper pectoral fin and
her barbels interlock and he curves his body toward her. After a short, shuddering embrace
a single egg pops into a cup formed by her ventral (pelvic) fins.
Even among catfish not all guys are equally lucky in love. We’ve all been there,
haven’t we? One male, who we’ve dubbed "Pencil Thin Mustache" because
of a short black horizontal line on each cheek, is almost always successful. Another male
with an unusually long dorsal fin almost never is, although he never stops trying. Alas
for him, in the world of Corydoras it’s "T" for two.
As soon as the egg enters her fin cup the female breaks away hoping for a short rest.
But her mate of the moment and other males as well swirl around her as she starts moving
around the tank. Although she displays no interest in them while cupping her egg the males
hound her relentlessly. A female’s search for just the right spot to deposit her egg
can last a minute or two or as much as 20 minutes. The time a female spends cupping each
egg seems to correlate with the number of eggs she lays. Once the egg is released the
courtship dance with the ever-eager males resumes.
Where the eggs are deposited varies with each individual female. And who can predict
what a female will do? Not me. So search the aquarium carefully. Many of the eggs are
attached to the front glass of the aquarium within several inches of the surface. Some
eggs are also attached to the tank sides and others to the plastic sword plant leaves. One
lonely egg was once left on the driftwood; another on the power head. Interestingly, a
good number of eggs are always placed both above and just below the water line in the two
front corners directly on the silicone. Some eggs are left a quarter inch or more above
the surface. The female "walks" vertically up the glass until much of her body
is out of the water to deposit an egg. Once the egg is affixed, she falls back into the
water. Eggs are also deposited above the water on the front and side glass. A female will
maneuver along the glass or plants any number of times before she leaves her egg.
The cats will eat some eggs during and after the spawning period. With a dozen fish in
the tank some are winning, others are losing, and some aren’t participating. They
look for food before and after (but never during) their romantic interludes. Keeping them
well fed reduces "poached" eggs.
The eggs are large and sticky. They readily roll off the glass or plants, between thumb
and forefinger, and stick to one’s hand on the day they are laid. The hard part is
getting them off! By the next day much of the stickiness is gone and the eggs are easily
dropped or damaged during removal. We remove the eggs immediately after or even during
spawning activity. If we interrupt them they’ll start in again as soon as we’re
done collecting eggs.
The eggs are transferred to a plastic specimen container to hatch. Water taken from the
breeding tank is used for incubation. Some eggs stick to the sides; others drop to the
bottom. A heavy air stone is placed in the container to aerate the eggs and several drops
of methylene blue are added to combat fungus. Because our basement is cold the container
is hung in a bare five-gallon aquarium heated to 75 degrees. The hatching tank is unlit
because the eggs are light sensitive. An air stone in the tank itself keeps the water
moving.
Fungus will claim some of the eggs. Not all of them get fertilized and the duds look
milky, get fuzzy, fall apart and cloud the blue water. The percentage of egg viability
varies with each spawn. Fertilized eggs darken and hatch in about four days. Some hatch
sooner, some later. Colder water lengthens the incubation period. Warmer water increases
fungus losses.
After hatching, the egg-sac wigglers are transferred to another five-gallon tank using
the catfish spawner’s secret weapon - a turkey baster. This bare bottom tank is also
heated to 75 degrees and contains a Hydro foam filter. The Hydro filter has a heavy
plastic base and elevates the foam above the tank bottom. This eliminates losses caused by
fry trapping themselves under the foam. In several days the egg sac is consumed and the
fry become free-swimming. Camouflaged with dark irregular spots on their gray bodies, they
don’t resemble their parents at all. Their striking adult white, black, and gold
coloration gradually appears after a few weeks. At first APR is fed three times daily. A
few days later frozen baby brine shrimp and micro worms are added. When the fry are big
enough food tablets and frozen brine shrimp expand the menu. (Another technical aside -
get your own turkey baster. Using the cook’s turkey baster can be harmful to the
fry’s health. It can also be harmful to the aquarist’s health. Trust me on this
one.)
As individual fish grow they are transferred to another identical five-gallon tank,
again using the turkey baster. Sorting the babies by size seems to promote individual
growth. Last stop is a 10-gallon rearing tank containing gravel, driftwood and live
plants. A Millennium 2000 filter is used. Our oldest offspring reside there now.
Cleanliness is next to Godliness when raising catfish. The glass bottoms of the
five-gallon tanks are cleaned daily using - you guessed it - the same turkey baster. All
uneaten food is removed. Care must be taken to avoid sucking up the little guys. We empty
the baster into a half-gallon plastic container and every now and then a cat must be
"basted" back. Needless to say, we never empty the container without checking
first. This process takes a few minutes but we have never developed the white velvet
bottom film that sends fry to heaven. (Yet another technical aside - the half-gallon
Gilles custard container works well and is highly recommended. Every fish fancier should
empty a few and keep them handy!)
About a half-gallon or so of water is changed in the two 5 gallon tanks daily.
Replacement water for them is taken from the egg-hatching tank. In this way, the water has
aged for 24 hours and is exactly the same temperature. Tap water tested for temperature by
our fingers (the original "digital" thermometers) is used to replenish the egg
tank. The water in the breeding tanks and the 10-gallon rearing tank is changed weekly
with water added as necessary to maintain depth.
Soon we’ll be able to sell our first batch of adolfoi. When one adds up the cost
of tanks, covers, heaters, filters, food, air pumps, etc., etc., and yes, even the catfish
spawner’s secret weapon, the turkey baster, we estimate that we should break even in
about 2010! After that, it’s all gravy! But I’m keeping my day job.
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