Catfish of the Month Right November 1998

Corydoras(ln9) similis
Smudge Spot Cory, Halvplettet Pansermalle (Denmark), Violet Cory, Violetta Cory - Corydoras (lineage 9) similis   Hieronimus, 1991

Article © Ian Fuller, uploaded November 01, 1998.

This catfish of the month is introduced by guest aquarist Ian Fuller, a self confessed "Corydoras Nut"; Ian has spawned over 40 species of Corydoras in his considerable time keeping members of this family. Ian has also contributed 3 excellent line drawings of this species' fry development you cn see in the breeding information section. Over to Ian...

The trouble with Corys is that if you put a group of say C. similis ( 6 or 8 ) together in one tank they'll act one way, move them into another identical set up and they'll act in a completely different way. When I first got my C. similis they were as busy as beavers. When, after a couple of weeks, I put them into a larger tank, they went to ground and just huddled under the heater. They emerged only to forage.

I tried various things to liven them up, raising and lowering the temperature, as well as water changes using warmer and cooler water. All to no avail. Resignedly, I put them back in the tank that they were first put in -and would you believe it - they went and hid under the heater. I let them be.

They became a little more active only when live food went in; white worm, tubifex or daphnia, one of which they were given at least once a week. Although largely inactive, all fish looked in fine condition, and the females in particular appeared rather plump.

After two weeks without water changes I did what I call my "classic water change": 80% of the water is removed and replaced with fresh water at least 7 to 10 degrees cooler. The cooler water is returned fairly slowly via a small spray rose on the supply pipe. There I go giving all my trade secrets away. Well some of them anyway! Two days after the water change they spawned. Only one female took part and she laid twenty eggs, which turned out to be infertile. A month later I used the same trick again, and with the same result, only this time the female laid about thirty eggs that also turned out to be infertile. Now an infertile spawning is one thing but two on the trot is something else. Nevertheless, after another six weeks I went through the same procedure, but, crucially, with water only 5 degrees cooler.

"Bingo!" 28 fertile eggs were laid. After the spawning was complete the adult fish were removed and released into their original tank. They were visibly more active and less secretive than before. Also one or two plants, in this case Java fern and or Java moss, seemed to make them happier.

Though that was in 1993, I am keeping C. similis again and find that they are just the same. I am about to put my current group into a tank higher up in the fish house to find out whether slightly warmer water will make them a little more active.

Copyright information for the images used in this article can be found on the species' full Cat-eLog page.

Down Cat-eLog Data Sheet
Scientific Name Corydoras (lineage 9) similis  Hieronimus, 1991
Common Names Smudge Spot Cory
Halvplettet Pansermalle (Denmark), Violet Cory, Violetta Cory
Type Locality Tributary of Rio Madeira, vicinity of city of Ariqumes, Rondonia State, Brazil.
Synonym(s) Corydoras similis
Pronunciation kor ee doh rass (lineage nine). - sim ill iss
Etymology . Latin similis = like alluding to the similarity of the colouration of this species to Corydoras ourastigma.
Down Species Information
Size 38mm or 1.5" SL. Find near, nearer or same sized spp.
Identification C. similis is the round nosed ''version'' of the long snouted C. ourastigma. The smudged marking at the base of the caudal fin separates it from other head-spotted species that have a distinct spot marking instead.
Sexing Female is fuller (when viewed from above) and larger.
Down Habitat Information
Distribution South America: Madeira River basin.
Amazon, Middle Amazon (Solimoes), Madeira (click on these areas to find other species found there)
Amazon, Middle Amazon (Solimoes), Madeira, Jamari (click on these areas to find other species found there)

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IUCN Red List Category Least Concern, range map and more is available on the IUCN species page. Last assessed 2018.
pH 5.6 - 7.0
Temperature 21.0-27.0°C or 69.8-80.6°F (Show species within this range)
Down Husbandry Information
Feeding Flake, tablets. Live food such as whiteworm, bloodworm, brineshrimp and tubifex (sparingly). Frozen bloodworm is more easily supplied and seems to bring on growth in sub-adults very satisfactorily. User data.
Furniture Other similar Corydoras, dwarf cichlids and tetras. A robust species that will adapt to larger peaceful tankmates.
Compatibility A perfect citizen.
Suggested Tankmates Ideally keep with dwarf cichlids and tetras. A robust species that will adapt to larger peaceful tankmates. Keep in groups of at least six.
Breeding 1. A ratio of 2:1 males to females has been successful at a pH of 7.2 and water at 76F which was reduced by approximately 5-6 degrees the day before spawning took place. It was back up to 76 when they began to spawn.
2. The spawning followed the typical ' T ' mating clinch, where the female nuzzles into the side of the male at a point just behind the pectoral fin. The male then clamps the female by her barbels (hence the need for good barbels, poor barbels means poor grip and possibly poor fertilization). Once the grip is complete both fish seemed to tremble for a few seconds, during this time the female deposited two 1.8mm eggs into a pouch made by clamping her ventral fins together. The female then broke away from the male and proceeded to find a suitable place to deposit her eggs. Altogether 28 moderately sticky eggs (out of a scale of 1 to 10 the these were 3) were laid all on the tank sides, all at various levels.
3. All the eggs were fertile and hatched in 4 days. 2 days after hatching the fry were free swimming and given pre-soaked powdered flake. This was followed by alternate small feedings of either brine shrimp or micro worm.
4. Fry Development is pictured above. The fry grew rapidly and at 7 days were 6.2 mm, at 14 days 9.0 mm, in 1 month 12 mm, after 2 months 16.4 mm, and after three months 21.0 mm. Adult colouration in 10 weeks.
5. After the spawning was complete the adult fish were removed, and the water treated with a few drops of methylene blue (1 drop per gal) to protect the eggs from fungal attack. Once the fry had hatched the water was changed at a rate of about 20% per day, for 5 days, removing the methylene blue concentration.
Breeding Reports There are 13 breeding reports, read them all here.
Down Further Information
Reference Zeitschrift für Fischkunde v. 1 (no. 1), pp 39, Fig. 1.
Registered Keepers There are 198 registered keepers, view all "my cats" data.
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Last Update 2020 Oct 22 04:42 (species record created: 1998 Nov 01 11:22)

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