Breeding Corydoras xinguensis
by Mark Bryson
First published by the Paisley & District Aquarist Society (Scotland), and
Scotcat.com
Aquarticles
After reading an article on the internet by Kristian
Adolfsson "Dry & Rainy
Seasons in the Tank" I decided to set up similar conditions in the hope of my
wild caught C. xinguensis breeding (3 males, 2 females).
Description:
C. xinguensis are from the Rio Xingu Estado, Mato Grosso area of Brazil.
Base colour grey, dark spots cover the body down below the level of the lateral line.
Lower body and belly region plain grey. On close inspection spots can be seen on the
dorsal and pectoral fin spines, caudal fin also has light spotting. Size 3.5 – 4cm.
Breeding Tank & Maintenance:
Tank: 18"x 8"x 8" with a small glass trough 8"x 2"x
2" placed to one side of the tank. This contained silver sand and was planted with
Indian Fern.
Filtration: Air-driven sponge plus box filter filled with ceramic rings and a small
amount of coral gravel to stabilise the pH at 6.5.
Feeding: I try to feed my fish at least twice daily with a good varied diet
consisting of the following: Tetra Prima, frozen bloodworm/ black mosquito larvae and live
grindal worms.
Preparation to Breed
Stage 1: I didn’t stick rigidly to
Kristian’s plan but used the basics, and started by reducing the water level by 10%
every two days until the volume of water had been reduced by 50%. By this time the plants
were just below water level. I also reduced the amount of feeding - some days no food at
all. Air flow into the filters was also reduced to a very slow flow. These conditions were
maintained for the next 21 days (no water changes were carried out during this period.)
Stage 2: I began reversing the process by adding fresh water, same
pH and temperature values, at the rate of 10% every two days. Feeding and filtration was
also increased at the same time until the tank was back to normal. I again increased the
feeding along with air supply to the filters, giving even more water movement to the
tank in an attempt to simulate nature during the rainy/flood season. Seven days later I
checked the water parameters: 73ºF/23ºC, pH 5.8. I decided to carry out a 50%
water change using water of 50ºF/10ºC, pH 6.9. Once the tank had settled the parameters
were 61ºF/16ºC, pH 6.4. The tank was then left alone to let things happen, if they were
going to happen.
Spawning:
First eggs appeared five days later on the bottom of the tank. I decided to leave
them in the hope of more to come. The following day I removed the six eggs and placed them
in a 4" cube show tank as I feared the adults may be egg eaters (I soon discovered
that my fears were unfounded). C. xinguensis eggs are very small, less than 2mm
in size, and sticky to the touch. Initially light sandy colour, turning to dark tan
during the 4 –5 days it took them to hatch (73F/23C). The following day there were
two more eggs on the floor of the tank, and while I was picking those up I brushed against
the Indian Fern and more eggs fell from the plant leaves. Inspecting the plants I
discovered over 40 eggs sticking to the underside of the leaves, some single eggs, some
pairs but never anymore than two eggs together on the same leaf. Unfortunately 60% of the
eggs were white and consequently proved to be infertile. What I did discover while rooting
about with the plants were fry darting around the plant trough, proving that the adults do
not eat either eggs or fry.
Fry:
When the eggs hatched the fry were a grey ball with a tail, 2mm total length. Day 2
they were free swimming. Fed for the first two days with diluted Liquifry, followed on day
three with microworm culture. Very soon they were eating newly hatched brine shrimp, fed
little and often. 50% water changes were carried out daily using water from the breeding
tank. Five days old the fry were starting to develop some speckling across the face and
head. Seven days old the spots were over the face and down their back, and they now
resembled Corydoras catfish. At this stage the fry were transferred from the
4" hatching tank to a 7" cube with a sponge filter. I also added to this tank a
piece of weighted Indian Fern - this provided refuge for the fry. As they progress they
will be moved to a larger tank. The original fry were removed from the parents'
tank, and within ten days more fry, approximately two days old, were siphoned out by
accident while doing a water change. Any further fry in the parents' tank will be
left there. These will be monitored as to their progress, comparing them with the 25 fry
that were removed as either eggs or fry.
Updated January 2001:
The above fry all did well. Some were passed on to friends, I sold to one or two to
local aquatic shops, and some were even sold at fish auctions to the true aquarists who
attend the shows/auctions. I was also awarded a First Time Bred & Shown Certificate by
The Federation of Scottish Aquarist Societies for breeding these Corydoras catfish. The
original five adult fish were passed on to Allan James [Scotcat] who also has had some
success in breeding them. The fry that I kept were left in the same tank since April 1999
and were given no special treatment - they were just left to grow up while I tried to
breed some other species of Corydoras, with some success I may say. In fact I
have bred 14 other species of Cory since I first bred
C. xinguensis. Yes I did say since I first bred them, because what were
the fry are now producing fry of their own, not that I have done anything special to get
them to breed - I just happened to spot some small fish in the tank. I say small fish not
fry because they had all the markings of the adult fish but were only about a third of
their size. This may help prove that F1 fish are easier to breed than wild fish, or is it
just sheer luck?
Reference: Kristian Adolfsson “Dry and
rainy season periods in the tank” http://www.roka.se/maf/articles/rainseason.html
and also on Aquarticles.com under Fish Breeding/Various.
This article also written for Paisley & District Aquarist Society, and Allan
James' Scotcat at http://www.scotcat.com , and the
Catfish Study Group [UK], and Steve Miles at http://www.catfish-corner.com
Any comments or thoughts on the above article can be sent to
the author at the following e-mail address m.bryson@ntlworld.com
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