Although known to science since 1971, my understanding is that up until late 2005 there were no specimens of this species for hobbyists to obtain for possible breeding attempts. If you have any experience obtaining species of fish new to the hobby, you can understand that the introductory price for these fish was quite high, and justifiably so.
Adult Corydoras weitzmani
Therefore, I was lucky to obtain 10 wild-caught adult specimens in early December 2005 from a local wholesaler's German import shipment. The fish were in excellent health and looked like young adults. The image above is an accurate depiction of their pleasing physical attributes. They are typical medium-sized Corys, averaging 2 inches long and being of average body depth for the genus.
According to the literature, this species is from the Rio Vilcanota system near Cuzco, Peru. A good buddy who has collected in South America a few times told me that the area around Cuzco (the city of Cuzco itself is at an elevation of 3000 meters) is quite cool and so they were introduced to a tank with a temperature range of 68-70°F whose pH ranged from 7.7 to 8.4. As it turned out, the information about their originating in the area around Cuzco was entirely wrong, bit the lower temperature didn't appear to do any harm - quite the contrary as you'll see!
The tank is approximately 20 US gallons (36"l x18"w x7"h), unheated, on a bottom shelf of one of my fish room racks. I have five of these tanks that I originally had built for raising large numbers of young Corys, and have found them extremely useful for many aspects of the hobby, probably due to the forgiveness provided by the large surface area to water volume ratio. The tank was filtered by a small hang-on-the-side power filter on one end and a sponge filter on the other. The current created was insignificant enough not to disturb any of the floating Anubias which covered 2/3 of the water surface, nor the large clump of Java moss at the opposite end from the power filter. The rest of the tank décor comprised of a 7" long cave made from cutting 3"ID ABS plastic pipes lengthways.
Most of my aquaria are devoted to breeding and raising fish, and so I'm not too concerned with lighting, and this tank was no exception, being lit by a single 2' fluorescent bulb. Enough to maintain the low-light plants and not so much as to compete with the Aurora borealis that we see here this time of year.
Initially, for the first couple of weeks, they were quite shy, spending most of their time under the structures provided for that purpose. They came out at feedings, especially when presented with white worms and/or chopped compost worms (also known as dwarf African red wrigglers). The daily feeding regime began with flake food first thing in the morning, followed by white worms, then the chopped compost worms, and finally one of the 3 different frozen foods ( bloodworms, brine shrimp or Mysis shrimp) given to the rest of my fish room's inhabitants in the late evening. After a couple of weeks on this diet they showed no conspicuous signs of "filling out" around the ovaries like other Corys do and still remained shy. The first water change altered their behavior significantly. After a 50% water change with cool water, which dropped the temperature down to 65°F., the group began demonstrating the ceaseless group exploration/pursuit of the tank parameters, typical pre-spawning Cory behavior. They continued this relentless movement for the next 2 weeks, which seemed a little long when compared with other Corys.
It was about a week later that I discovered twenty 3mm fertile eggs laid singly on the underside of the leaves of the floating Anubias. I removed them to a medium-sized plastic container in about 2" of water with slight aeration. Hatching proceeded as expected for Corys (taking a little longer than the normal four days due to the lower incubating temperature) and raising them on microworms and then baby brine shrimp has proceeded well. The fry are a mottled colour initially and after a few weeks start to adopt the 3 large black spots of the adults.
Young at six weeks, photo: Ian Fuller
Slightly older youngster beginning to show adult patterning, photo : Ian Fuller
Since their initial spawning I have had a chance to collect eggs several times (I'm sure I missed some due to a recent surgery) and can relate the following points as to their reproduction:
- They do spawn during the daylight hours
- They are voracious consumers of their own spawn. More than a few times I've observed them spawning and have seen eggs laid singly on the glass only to come back an hour later to a bare glass surface. This can make finding the eggs post-spawning very challenging, a tedious task for those of us who are not quite as smart as the females who hide the eggs.
- 99% of their eggs are laid singly, and only very rarely will you find a double set of eggs
- It seems that different females prefer different media in which to deposit their eggs. After the first couple of spawnings a friend suggested that I offer them a yarn mop as a potential deposition site. The next spawn most of the eggs were in fact laid in the mop with the rest in the Anubias. Since then I have added a floating strip of artificial "spawning grass", another site chosen for their eggs. In the spawnings since then I have observed spawns where most ( 75-90 % ) of the eggs were laid in the Java moss with the remainder in the Anubias, most in the spawning grass and the remainder in the Anubias, most in the Anubias with the rest in the mop, and so it appears that the females are particular as to the chosen egg site on the day, although the Anubias seems to be a common denominator. Whether specific females consistently choose the same spawning sites is tough to observe in this large a breeding group.
- They have a robust appetite, which seems to be the sole requirement to induce breeding. I'm not sure that specific water values are required for reproduction, and would be interested in hearing from others who have future experiences propagating this species. I am positive that there will be others, as when compared to other Cory species this doesn't appear to be a particularly difficult species to spawn.
I must thank Rudy Kern, owner and operator of Aquatic Plants Unlimited, for having enough confidence in me to entrust to me the responsibility of the challenge of this species.
There is further information on this species on the Cat-eLog page.
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