Corydoras species: a few of so many

Corydoras æneus (Bronze Cory Cat). When I look at the armor of this armored catfish, mixing the colors of bronze and verdegris, it's pleasant to recall that Virgil's epic hero, the one who fled Troy, the mythical founder of Rome who loved Queen Dido, was Æneas. His name means "the bronze-armored one." Even "Corydoras" speaks of the armorer's craft, for it means "the Doras— that's another catfish— with a helmet." This Cory has a wide distribution from Venezuela (and even Trinidad, where the species was first discovered, in 1858) south to La Plata. Some localized populations of C. æneus do show a streak of intense green, though maybe the recent marketing names like "Neon Green" and "Laser Green" overstate the effect. In 2000 I started to see "Peru Green" Cories at New York LFS, with all but day-glo colors, both lime green and orange. I was unconvinced of their authenticity, even of the "Peru" part. But Don Kinyon has been spawning these "Laser Green," "Red Stripe" and "Orange Stripe" cories, which may or may not be local variant populations of C. æneus, and he notes that the resulting fry do display their parent's amazing colors. Read his article, "The Colors of Corydoras."
 
When fish are tank-bred for generations, as C. æneus has been, inbreeding can reinforce recessive genes for albinism and melanism. Albino Corydoras æneus are familiar enough; their pink and pallid colors have all the charm of uncooked chicken breasts. But in 1990 a Canadian? aquarist bought some melanistic (entirely black) mutations that are probably C. æneus, which have been distributed among a few cognoscenti around North America. They are said to have come from Rio Apure, a Venezuelan river that flows into the Orinoco, but the specific collecting site of interesting fishes is often a trade secret. They are unusually handsome, with almost black bodies and garnet-brown finrays, though I hear that they are not quite so hardy as standard C. æneus. Few albino fishes appeal to me, but I think these black Cory cats are the most desirable Corydoras I've ever seen, though I still know them only from a photo.
Corydoras aeneas was Catfish of the Month at PlantCatfis,h December 2001.
 
C. paleatus. It's pleasant to remember that C. paleatus was first collected in Argentina by Charles Darwin, who was on his way south towards Cape Horn, in the role of gentleman companion to the captain of H.M.S. Beagle. The species was scientifically published using Darwin's specimens in 1842. The name paleatus comes from Latinpalea, which means chaff. Linnaeus used the word in botanical descriptions, and one of its botanical senses has come to refer to the overlapping scales at the base of the flower that you see if you turn over a daisy. So this "paleate" Corydoras has comparable overlapping scutes or armored scales. Elegant scientific naming makes you look twice!
 
These were the first Cories that spawned for me, in wintertime, with slightly cooler aquarium temperatures, about 75°. I never caught them at it, just found the single or paired eggs, carefully hidden near one another, mostly on the glass. C. paleatus was the first Cory that spawned in an aquarium for anyone, but it wasn't til the 1990s that aquarists realized how to trigger Corydoras breeding with massive changes of softer water at cooler temperatures, about 70°. Breeding season at home is October through March— the high water season.
 
Larry Vires wrote an excellent account of breeding Cories in Aquarium Fish, July 1998. Corydoras paleatus was "Catfish of the Month", March 1999 at PlanetCatfish.
 
Corydoras pygmæus. Their homes are small tributary streams of the Rio Madeira, a tributary of the Amazon. They weren't known until 1966. They'd be easy enough to overlook: adult length about an inch. I bought mine as C. hastatus, but when I got them home I recognized that they were C. pygmæus. 
 
Mike Edwardes had success with these, until newt eggs he brought in with some Myriophyllum from a garden pond hatched in his absence and ate all his C. pygmæus fry. An interesting disaster. He has three side-by-side photos that make it easy to identify which of the three mini-Cories you have: C. pygmæus, C. hastatus or C. habrosus. The key to success, for Mike Edwardes, is in giving them a small tank all to themselves: " These diminutive fish seem to be intimidated by even the most innocuous of tankmates." And in reducing opportunities for fungus with lowered pH, rainwater and peatwater tannins.
 
Kaycy Ruffer tells how to distinguish the mini-Corydoras and how C. pygmaeus spawned for her and how she raised the fry, at PlanetCatfish 
 
C. panda. C. melanistius ("C. julii"). C. rabauti "myersi". I've had each of these at one time or another. C. rabauti was named for Auguste Rabaut, the indefatigable collector based in Brazil who in 1935 was the first to export a shipping can full of Neon Tetras, to a French banker; so pronounce this species' name "ra-BOW-tie". C. rabauti appeared in New York for the first time in 1939.
 
I especially like the subspecies named for Dr. Myers, which is distinguished by a dark smudge that looks like a black eye; it comes from small Amazon tributaries upstream from Manaus.
 
C. schwartzi. These are found in small streams near the mouth of Rio Purus, Brazil, a tributary of the Amazon. This species was named in 1963 for the late Willi Schwartz, the exporter based at Manaus whose wife is the Robine of Corydoras robinæ and whose son Adolfo has been complimented in C. adolfoi. A dark head with an even darker "black eye" and black spots, which tend to arrange themselves in rows down the flank and to form vertical rows across the tail are features that give this species distinctive panache. The silver background is crisply metallic, the belly pure white. I currently have a group of five. From their large size, their broad beam as seen from above and their portly carriage, with slightly swelling bellies, I fear that they're all females. These are a little shy. In the evening, I lure them out of the shadows with Hikari wafers and sit quietly in a dim room to enjoy them. They form a shoaling group in a gentle current and hold formation in midwater, or they'll form a "stacking pattern" above one on the gravel. (Is this a courtship move?) Not all Corydoras hug the ground. Some, like Schwartzies, can be found at all levels in the aquarium, sometimes perched on a sturdy leaf. In part it is by dividing up the available territory, that Corydoras species can specialise, so that two Cory species can co-exist ("sympatrically") in the same shallow backwaters.