| Scientific name | Undescribed — catalogued as CW111 |
| Common names | Vulcan Corydoras, Vulcan Cory, CW111 |
| Origin | South America, western Amazon drainage; commonly attributed to Peru. Exact type locality not firmly established |
| Adult size | Approximately 2 in (5 cm); reports vary |
| Minimum tank | 20 gallon long (30 in / 76 cm footprint); 29–40 gallons preferred |
| Group size | 6 absolute minimum, 8–10+ strongly recommended |
| Water parameters | 72–78°F (22–26°C), pH 6.0–7.2, soft to moderately soft, nitrate under 20 ppm |
| Temperament | Peaceful, social, bottom-dwelling |
| Care level | Intermediate — not delicate, but demands stable water and correct substrate |
The Vulcan Corydoras — catalogued as CW111 and sold in the trade as the Vulcan Cory — generates far more search traffic than it does sales, because so few reach the United States in any given year. It is a small, high-contrast South American catfish with no scientific name and a following of collectors who drop everything when a shipment lands. Here is what CW111 actually is, how to tell it from its lookalikes, and how to build a tank that keeps a group healthy for the better part of a decade.
One thing up front: the Vulcan Cory CW111 product page is where this fish appears on our site when it returns to the list, and it is not in stock as this is written. We are not going to invent an arrival date or a price. If you are building the tank now, watch our Corydoras category.
What the “CW” in CW111 actually means
Collectors pull visually distinct Corydoras out of Amazonian tributaries faster than ichthyologists can describe them, which left the hobby with dozens of recognizable fish and no valid names to trade under. Two cataloguing systems filled the gap: the older C-number series from the German aquarium press, and the CW-number series maintained by the British magazine Practical Fishkeeping. A distinct undescribed form gets a number, the number sticks, and everyone in the supply chain uses it to mean the same fish.
So CW111 is a catalogue code, not a species name, and “Vulcan Cory” is a hobby label on top of it. As of this writing the species remains undescribed, and we will not attach a Latin binomial that does not exist. A seller listing CW111 with a confident-looking scientific name is a red flag about the seller, not a fact about the fish.
There is a second layer of confusion. The genus Corydoras has recently been split, with familiar species reassigned to genera including Hoplisoma, Osteogaster and Brochis — which is why so many listings now carry two names at once and buyers keep asking whether they are looking at the same fish relabeled. For CW111 the question is moot: an undescribed form gets no confirmed genus until somebody publishes the description. Anyone telling you which new genus CW111 belongs to is guessing.
Appearance, and what CW111 gets confused with
CW111 is a compact, deep-bodied Cory in the two-inch range with strong dark markings over a pale base — the kind of high-contrast patterning that photographs beautifully and drives the price. Like all Corydoras it carries two rows of overlapping bony plates down each flank, a downturned mouth ringed with barbels, and stiff leading spines in the dorsal and pectoral fins.
The practical problem is that many rare Corys look alike through cloudy shipping water. Pattern intensity shifts with mood, substrate color and stress: the same fish can look washed out in a bare quarantine tub and dramatically marked over dark sand two weeks later. That is exactly how mislabeled fish move through the trade. Ask for a photo of settled, feeding fish in a sand-bottomed tank, never a bag shot. It also helps to have seen the other collector-grade Corys side by side, such as Gold Laser Corydoras CW010 or the CW217 Rio Tomo Concolor Cory, which rotate in and out of availability the same way CW111 does.
Fine sand is not optional
If you take one thing from this guide, take this. Corydoras require fine, smooth sand. Not small gravel. Sand. A Cory feeds by driving its snout into the substrate and sifting, using soft barbels as chemosensory probes. Push those into sharp gravel thousands of times a day and they abrade, get infected, then erode away. A Cory with stubs where its barbels should be has lost its primary way of finding food, and the damage does not reliably come back. Barbel erosion is the most common welfare failure in Corydoras keeping, and it is entirely caused by the keeper.
- Fine, rounded sand around 0.5–1 mm — pool filter sand and inert aquarium sands both work.
- Keep the bed shallow, about 1 in (2.5 cm), so it stays oxygenated.
- Avoid sharp construction silica and calcareous substrates that push hardness up.
- Stir and siphon the top layer at water changes — a mulm-loaded sand bed is a nitrate factory.
The second non-negotiable is unobstructed access to the surface. Corydoras supplement gill respiration by gulping atmospheric air and absorbing oxygen through a modified, heavily vascularized section of the intestine. That dash to the top is normal, not distress. It does mean floating plants must never form a complete mat and the water line must never sit so tight against a lid that the fish cannot break the surface. A sudden increase in surfacing, though, is worth investigating — usually low dissolved oxygen or a water quality problem.
Tank size, water parameters and filtration
Footprint matters more than volume for a bottom-dwelling shoal. A 20 gallon long gives six fish about 30 inches of foraging lane, which is workable; a 29 or 40 gallon breeder is genuinely comfortable and lets you run eight to ten, which is where the behavior gets interesting. Tall narrow tanks waste most of their water on a species that lives in the bottom four inches.
Target 72–78°F (22–26°C) and resist running rare Corys hot — sustained heat shortens lifespan and raises oxygen demand exactly when a wild import can least afford it. Aim for pH 6.0–7.2 in soft to moderately soft water, and remember that stability beats chasing a number: a rock-steady 7.2 is better than a 6.5 that swings half a point weekly. Our aquarium water parameters cheat sheet covers the ranges and a sane testing cadence.
Two sensitivities deserve their own paragraph. Corydoras are intolerant of accumulated nitrate — keep it under 20 ppm, preferably under 10 for wild fish, which means real water changes rather than top-offs. They are also sensitive to salt: scaleless catfish do not tolerate the aquarium-salt dosing routinely recommended for general fish treatment, and several common medications carry warnings for them. Read the label before treating a tank with Corys in it. For filtration, aim for good turnover with gentle flow at the substrate — a canister with a spray bar along the back glass, or a sponge filter with a small powerhead.
Group size and shoaling behavior
Six is the floor, not the target. Below six, Corydoras stop doing the things people buy Corydoras for: the coordinated sweep across the sand, the group surfacing runs, the pile-up under a piece of wood at lights-out. A group of three hides; a group of ten forages in the open in the middle of the day.
With a fish this scarce there is real pressure to buy four now and add more later. That usually fails, because “later” for a CW-number Cory can mean eighteen months and a different collection point. Budget for the full group in one order. Mixed-species Cory groups shoal together loosely, but they do not spawn across species and the social behavior is visibly weaker than a single-species group of the same size.
Feeding: the “they’ll eat the leftovers” myth
Corydoras are not a cleanup crew. They do not eat algae or fish waste, and they will slowly starve in a tank where the only food reaching the bottom is what the tetras missed. This is one of the most common ways keepers lose them, and it is slow enough that most people blame something else — a thin, sunken belly and a fish that stops foraging is very often just an underfed Cory.
Feed the bottom directly, after the mid-water fish have had their fill. A sinking pellet or wafer that holds together on sand is the backbone of the diet: Discus Hobby Pleco Tablets sink immediately and stay put long enough for a shoal to work them over, and a granule such as Discus Hobby Premium Daily Food soft granules covers the everyday staple.
- Staple: sinking granules and tablets sized so the fish can actually take them.
- Protein rotation: frozen bloodworms, daphnia, brine shrimp or live blackworms two to three times weekly.
- Feed after dark for shy or newly imported fish — wild Corys settle into a night routine fastest.
- Judge by belly profile, not the clock. A well-fed Cory is gently rounded underneath, never sunken.
Tank mates for CW111
Vulcan Corydoras are peaceful to the point of being pushovers, so the rule is simple: nothing that outcompetes them at the bottom, nothing large enough to swallow a two-inch fish, nothing that nips fins. Small tetras, pencilfish and rasboras in the mid-water are ideal, and dwarf cichlids such as Apistogramma work if the footprint is large enough that a spawning pair is not defending the whole substrate. Avoid large cichlids and aggressive bottom feeders that monopolize sinking food. Note too that the pectoral spines of a Corydoras lock outward, which is a genuine hazard for a predator that grabs one — usually fatal for both fish.
Breeding: what applies, and what nobody can tell you yet
General Corydoras breeding is well understood and CW111 most likely follows the standard pattern. Females grow larger and noticeably broader viewed from above; males stay slimmer and more pointed. Spawning is typically triggered by a large water change with cooler water, mimicking a rainy-season influx. The pair adopts the characteristic T-position, the female carries a small clutch of eggs in her cupped pelvic fins and presses them onto glass, leaves or filter surfaces. Eggs hatch in roughly three to five days depending on temperature, and adults will eat them, so most breeders separate eggs or parents.
What we will not claim is a documented, repeatable breeding protocol specific to CW111. Rare CW-number Corys often go years without a published spawn report, and where reports exist they can be single anecdotes rather than reproducible method. Treat it as an experiment and be skeptical of any confident CW111 breeding recipe you find online. For a similar-difficulty fish with a far better documented track record, see our Corydoras eques care guide.
Rarity, availability and buying rare Corydoras online
CW111 is scarce for structural reasons, not marketing ones. Undescribed Corys come out of specific collection points on a seasonal schedule, depend on a handful of exporters, and a bad water year or a permitting change can take a fish off the market for a season or more. Availability is lumpy: nothing for a year, then a few groups, then nothing again. Anyone quoting a firm restock date on a wild CW-number Cory is telling you what you want to hear — we would rather say we do not know. Thin supply also attracts sloppy labeling, so check a few things before sending money to any seller, us included:
- Ask about quarantine. Wild-collected Corys arrive carrying parasites more often than not. We run multi-week quarantine with prophylactic parasite treatment and confirm fish are eating before anything is listed.
- Ask whether they are eating prepared food. A wild import that has not transitioned onto pellets is a far harder fish than the same species six weeks later.
- Check the shipping method. Live fish move overnight, full stop — we ship FedEx Priority Overnight, UPS Next Day Air and Southwest Cargo across the US and Puerto Rico.
- Read the arrival guarantee before you order. Ours is a 100% Live Arrival Guarantee: photograph any loss in the unopened bag within one hour of delivery and we issue store credit. Shipping charges are non-refundable.
- Buy the whole group at once. With rare imports there is often no second chance from the same collection.
Wild-collected fish from small Amazonian fisheries are, in many regions, the economic reason those waterways stay intact — something we get into in our piece on wild-caught fish, genetics and conservation. Losing a CW111 group to gravel and leftover flake food wastes a genuinely limited resource. Get the sand and the group size right first, and be ready when the fish show up. When CW111 comes back into rotation it will appear on the Vulcan Cory CW111 page. Amazonia Tropical Fish LLC ships from Philadelphia, PA, with free shipping from $350 within the continental US.