Corydoras sp. C121

by Graham Ramsay

t’s a fact that while the descriptions of new species of birds or mammals are rare enough events to merit time on the national news, hardly a day goes by without a new catfish appearing on importers lists. Such is the rate of discovery that science is unable to keep up with the hobby, Hence the advent of L numbers and C numbers for the Loricariidae family and Callichthyidae family respectively. One of these undescribed Corydoras is C121. Closely resembling Corydoras burgessi, it is sometimes given the unwieldy label of Corydoras cf. burgessi. Here, cf. means confer (different). So Corydoras cf. burgessi means an undescribed fish that is probably a form of C. burgessi. Whether it turns out to be a form of C. burgessi or a new species is not important. It’s an attractive and interesting fish in its own right.


Adult female C121 with a young C. panda

Adult female C121 with a young C. panda

C121 started to appear in the UK in reasonable quantity in 2004. I wanted a breeding group but the cost was prohibitive. It’s always worth scanning the tanks of fish shops as you never know what might be there and sure enough, that autumn my local garden centre had a group of “Panda corys” for sale, at panda Cory prices. I bought all seven (and a lone C. adolfoi) and the “pandas” where safely installed in their new home, a 36” x 12” x 12” bare-bottomed tank. I set about conditioning the fish and fed them a varied diet of flake, pellets, frozen bloodworm, white worm, grindal worm and any live food I could lay my hands on. Tank parameters where nothing out of the ordinary, although my water is extremely soft. pH was neutral and the temperature was set at around 76F. As they filled out it became clear I had three females and four males.

In the spring of 2005 I put some young Microgeophagus altispinosus in the tank to grow them on. As part of that process I was changing around half the water twice a week. The inevitable happened and the C121 started to spawn, depositing eggs on the tank walls. I moved the catfish into an 18” x 12” x 12” tank on their own with sunken and floating spawning mops and a small internal filter. After a day or two they continued spawning. And wouldn’t stop! Each spawn was around 20 – 50 eggs and took place once or twice a week.


Adult female C121 with an egg in its claspers

Adult female C121 with an egg in its claspers


The fish spawned in the late evening, before the lights went out, this made collecting the eggs easy and I soon had hundreds. Eggs were deposited mainly in the sunken mops but also on the glass, filter, plants, and even the bottom. The large eggs were hatched out in ice cream tubs floating in another tank before being let loose when they were free swimming. I fed them on microworm and crushed flake for the first week then newly hatched brine shrimp and crushed flake after that.


Newly hatched C121 fry

Newly hatched C121 fry


It was now that I started to experience significant loses of fry. For every ten eggs I collected I was losing around five or six fry at around 7 – 10 days old. I tried various things before I noticed several fry had abraded pectoral fins. Suspecting a bacterial problem, I decided to add a thin layer of sand to the bottom of the fry tank. Almost overnight the fry loses stopped. Since then I have kept all my Corys on sand and would recommend this over bare-bottomed tanks. Certainly for bottom living fish (including those that rest on the bottom at night) this seems prudent.

I now had well over 200 fry and more eggs to hatch out. Incredibly the adults showed no inclination to cease spawning but the eggs where smaller and I decided to separate the sexes and move them into other tanks. I now had more than enough fry to grow on and had to dedicate two 18” x 12” x 12” and a 36” x 12” x 12” for that purpose.


C121 fry  7 weeks old

C121 fry – 7 weeks old

The young cats grew fast to begin with on the usual fare of baby brine shrimp, grindal worm and crushed flake and the adult pattern was fully apparent at about 12 weeks. After this time growth slowed down considerably. The feature for which C121 is known, the brown patch behind the gill cover, didn’t appear until the fish were around 4 months old and about 3cm in size.


C121 fry  12 weeks old

C121 fry – 12 weeks old


Shifting the young fish was easy; such attractive little cats are always in demand both in the shops and at club and society auctions. As so often happens with new Corydoras, C121 have become scarce in the shops again so I may well return to these fish in the near future and attempt to breed them once more.

Whatever name is eventually given to this fish it deserves a place in the hobby. Attractive, peaceful, easy to keep and to breed, this is an ideal choice for those just starting down the road to Cory nuttiness.

Images by author

Fair City Aquarist Society September 2006


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