The Skeptical Aquarist

Catfishes (Siluridae).

Catfish links. Catfish inspire devotion from their keepers second only to Cichlids.Consequently there are several websites that concentrate on catfish:

http://www.planetcatfish.com Since 1996 this has been where to begin with catfish. The largest catfish photo archive on the net is now expanding into an informative database. Wide-ranging features include "catfish-of-the-month," illustrated articles that are much more anecdotal and informative than the usual web species profile, Loricariid "L-numbers," brief synopses of recent scientific catfish articles etc., a catfish forum, plus a hub for well-chosen links, with succinct notes on what you can expect to find. Shane Linder presides.

http://www.scotcat.com ScotCat offers very good articles on catfish care and breeding; you can even discover what your catfishes' scientific names actually mean! Allan James is in charge.

http://www.catfish-corner.com/main.html The lively articles are my favorite aspect of this club site.

Callichthyidae.

The Neotropical catfish family Callichthyidae is found in most South American river drainages: Paranà-Paraguay, São Francisco, Atlantic Coastal basins in Brazil, the Amazon, Orinoco, Maracaibo, Magdalena, as well as in a few rivers in Panama. They present their highest diversity in the headwaters of the Amazon drainage and in the rivers draining the Guianan shield, an ecological success that even outdoes Apistogramma.

Links. Robert Reis' former pages devoted to the Callichthyidae,— their phylogeny and geographical distribution,— offering a catalogue of 130 Corydoras species have been pulled, but his abbreviated introduction, cladistics and references are in the Tree of life Web Project.

Corydoras spp. The genus Corydoras has racked up spectacular successes in small shallow watercourses from the Orinoco basin to the Paraguay. A local population of C. æneus even got stranded in Trinidad when sea levels rose at the end of the last ice age. Over 138 species have been scientifically described, and almost 60 more have been assigned temporary "C-numbers." In their isolated streams, often two or three Corydoras species will be discovered living together ("sympatrically"). How they maintain their individuality as distinct species, by what subtle isolating mechanisms of pre-spawning behavior or timing, or perhaps characteristic odors, will provide material for many interesting studies in the new field of "ecological speciation." It seems a shame that we like to bundle them all together in mixed Cory herds and encourage them to hybridize.

There's a recognizably Corydoras-like fossil, 59 million years old, reported John Lundberg, who was exploring Amazonian fish diversity in Natural History, Sept 2001. That would place an identifiable Corydoras in the Palaeocene, along with the first primates and the radiation of flowering plants. The fossil, called Corydoras revelatus, was found in the 1920s by Prof. Cockerell in El Sunchal, Jujuy Prov., Argentina, and deposited in the British Museum. There are photos of the little fossil Cory at www.scotcat.com

Air gulping. Every so often your Cories will make a dash for the surface to gulp air. A highly-vascular section of the intestine serves as an accessory respiratory organ. The spent air, mostly exhausted of its oxygen, is expelled from the anus. In Corydoras, the swallowed air plays an even more important role in hydrostatic balance, keeping the fish neutrally buoyant.

Barbel erosion. Generally Cories are among the least demanding fishes. One problem with keeping Cories under imperfect conditions, however, is that their barbels may erode. The ineradicable folk tradition has long been that the barbels were being "worn away" by sharp gravel. I think that a fish that was prone to suffer this way could only evolve in habitats with very fine silty bottoms, and that consequently it would have a limited distribution, whereas every stream catchment area throughout wide stretches of the Amazon-Orinoco basin has its own Corydoras species— and often two of them, co-existing side by side. How could any organism evolve so delicately mis-tuned to the varying sands and gravels of its streambed environments and yet be successful over such a wide area? If you think some streambed gravels are rounder than others, keep a 10x loupe by you and check out all the streambed gravels you can find.

Some Cory keepers feel that barbel erosion is more likely due to bacterial/fungal attack, and that it may be reversed when water conditions are improved. One mention of bacterial barbel erosion, in C. concolor, is in an article by Allen James (of www.scotcat.com) archived among "Catfish of the Month (April 2000) at www.planetcatfish.com.

Cathy Quinones posted at rec.aquaria, 3 June 1994, that her C. julii lost their barbels but regained them when their diet was improved (with tubifex); see http://www.thekrib.com/Fish/corydorus.html

Bacterial infections are generally secondary. The primary culprits in barbel erosion may be skin flukes. A report of barbel "detachment" in ictalurid cats being aquacultured, which is ascribed to necrosis from gyrodactylus (fluke) infestation, is mentioned in a Massachusetts Coastal Zone Management white paper. Could these parasitic trematodes be an issue in Corydoras barbel erosion also?
My own experience suggests that barbel erosion might be related to long-term elevated nitrate levels. Some of my C. schwartzi have experienced eroded barbels when nitrates remained about 40 ppm. Is there a connection here?

Almost like an answer to these concerns, RTR posted at AquariaCentral, 30 Aug 2001:

"This particular myth has been around almost as long as I've been keeping fish, and it refuses to die.

"One of my favorite test tanks used crushed glass substrate (not kiln-softened) and a school of C. arcuatus corys (personal favorites) with fractured glass slab "rockwork". A part of the same shipment of corys went into a nearby planted tank with which I had been having problems with a high-organic substrate. After just a few months, guess which tank had barbel erosion? And a few weeks after unifying the schools, guess who started recoving their injured barbels while living over crushed glass? I had in the past experienced occasional barbel problems in corys (and Brochis-- they are more sensitive IME), and always had credited it to maintenance, and was able to clear it with good tank upkeep. That fact and loss of dwarf cichlids kept in organic-substrate tanks cured me of ever having a high organic substrate again. That problem tank was the last, and I'll never have such again.

"I don't use the crushed glass any more either. I really just set it for a temp tank for the test. In the year+ it operated, I had no problems with it, except that it grew algae. I do have some crushed black glass substrate, but it has been kiln-softened to round the sharp edges.

"Corys in the wild live over a wide variety of sustrates, from silt/mud to rocks, and they are adapted to substrate digging. You would expect some abrasion of the barbels over anything but fibrous peat (as used for killies), but if the substrate is clean, they will not suffer the secondary infections they will over polluted substrates. The secondary infections are what erode the barbels, just like fin rot does for the unpaired fins of free-swimming fish.

"They do prefer more sandy substrates, and will dig more freely in soft sand than in gravel by a wide margin. But they can be kept over either without damage, so long as it is clean, and they can suffer erosion over either if they are not.

I do not have much experience with Pictus cats, but I do know their barbels are nitrate-sensitive."

Corydoras links.

Ian Fuller, chairman of the U.K.'s Catfish Study Group and the author of Breeding Corydoradine Catfishes, maintains a website Corycats: the wonderful world of Corydoradine catfish devoted to articles by him and others on keeping, and especially on breeding Corydoras and their close relatives, Aspidoras and Brochis. You'll find excellent photos of just about all the named Cories, and the un-named ones, currently being given C-numbers, too. Corydoras weblinks complete the picture.

You might also check the ID of your Corydoras among the huge repertory of Cory photos, accurately identified, in the "Corydoras Encyclopedia" at Yamamoto Yutaka's website "I Love Corydoras": http://www.mars.dti.ne.jp/~yamyam/index-e.html Japanese fishkeeping is long-established, high-energy, and full of its own characteristic flavor!

Of course Corydoras figure at www.planetcatfish.com and Allen James has a Cory section at ScotCat www.scotcat.com, where you'll also find Ian Fuller's article "Starting with Corydoras."

Mike Edwardes has some good information about half a dozen Corydoras species at his site "Mike Edwardes Tropicals", where he archives an article "Stumped? Secrets of a Corydoras breeder." Some good Cory links here, too.

There's a set of good articles on Corydoras species by Paul Schuman at http://www.aqualink.com/columns/k-cory.html.

Eric Bodrock's modestly titled "Cory crumbs" at AllOddball Aquatics (select "Articles" in the menu) are really more than just crumbs of information about breeding over thirty species of Corydoras through the years. His tanks share a central filtration system, and he finds that a spawning in one tank will set off a whole chain of spawnings through the system. If you're cories are spawning in one tank, it seems to me you could encourage other Cories by adding a gallon of water from the spawning tank. You'll find more articles by him at Ian Fuller's site mentioned above.

Dr David Sands' volume devoted to Cories, Keeping Aquarium Fishes: Corydoras, covers the Cories he knows so well in the wild and in the aquarium: keeping them happy, feeding and breeding them. Dr Sands also offers a CD-ROM with over 30 minutes of Corydoras videos, if you just can't get enough Cory lore. Alas, Dr Sands' promotional website isn't very informative.

Rare Cory "contaminants." Sometimes quite rare Corydoras get shipped as "contaminants" with similar-looking but more commonplace species. Sort of like rubies "contaminating" a shipment of garnets, eh. Sharp-eyed and knowledgable Cory geeks lurk on fish-delivery day at a good LFS that isn't too far down the chain from the original importer, and they get to snap up the rare ones.

Mixed "breeds." What might look like rare "contaminants" in a shipment of farmed Cories are increasingly likely to be a sign that the whole bunch are casual hybrids. Hybridizing might be more excusable among amateurs. Confined in our aquaria, one or two individuals of mixed Cory species commonly find themselves thrown together by fishkeepers with a stamp-collecting bent, who think of them as merely "varieties."

When Cories are put together like a bowl of mixed fruit, hybridizing can occur. Why is hybridizing such a poor idea? I've never been able to satisfy anyone who asked this question. Decreased fertility in the second generation never seems like a problem to the questioner somehow. I feel that it's disrespectful of the fishes. Hybridizers imagine that something "new" could be created, if you could select these spots and combine them with that dark head, etc.. I feel instead that some fine-tuned species could be lost if we blur all together into one general-issue "mixed Corydoras" aquarium strain. (In the U.S. this is already happening to Lake Malawi cichlids.) A fastidious aquarist won't force mixed company on the fishes in his or her care. When someone asks whether it's okay to mix Cories, I say, "Imagine that you've been abducted by aliens. Kind-hearted, responsible aliens, who have conscientiously done their homework: they studied your DNA, and now they set you up in the equivalent of a high-end Hospitality Suite. Your roommates, for the rest of your life-span (your DNA checked out as almost identical) are ...two chimpanzees...."

Spawning. More and more species of Corydoras are spawning in aquaria, even the species that had a reputation for being difficult, now that we understand the basic triggers that initiate their spawning cycle. In their native waters, apparently Corydoras spawn when temperatures drop in the first floods of soft water after a storm. Recreating this event can be as simple as a massive water change with cool water (under 70º even); a refinement is to time the water change to follow closely after a sharp drop in your local barometric pressure: check the Weather Channel. This sounds like a smart trick to remember. But then, I also like the charming true story of the devoted Cory lover who rattles sheets of galvanized tin to create a boom of thunder in the fishroom and sprinkles "rain" from a watering can! There are variations on the Corydoras breeding theme. Follow the details in articles on breeding various Cories at www.scotcat.com.

Robert Goldstein wrote about spawning Corydoras and their Callichthyid relatives for Aquarium Fish, Oct. 1991, in the AF archive and Alan Hosking-James offers his techniques, "Breeding Corydoras (and Brochis) spp." at www.e-aquaria.com . Also you may want to read Mike Edwardes Cory breeding FAQS at www.planetcatfish.com.

Cories are sensitive to medication. Years ago, when tests were done to test the salt-tolerance of freshwater fishes, Corydoras died first. Malachite green will poison Cories before any other fishes are affected; it took me years to learn never to use Malachite green on a Cory cat. I pass this on to you.

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.

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 a 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 Latin palea, 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 home 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 they spawned for her and how she raised the fry, at www.PlanetCatfish.com

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. By dividing up the available territory, Corydoras species can specialise, so that two Cory species can co-exist ("sympatrically") in the same shallow backwaters.

Dianema longibarbis (Porthole Catfish). In all the attention lavished on adorable Cory Cats, which is well deserved, I know I've always neglected their close cousins among the Callichthyinae, the bubblenest-building subfamily. So now I've got four young Dianema longibarbis, which is smaller (getting to about five inches) and easier to keep than either of the other two Callichthyinae genera, Hoplosternum or Callichthys. They're mouse-colored, with a large dark eye and speckles that arrange themselves into a line of "portholes" down the flanks, strongly countershaded with a white belly. Porthole Cats are like Cories redesigned on racier lines for grace and speed, with a long flattened snout that carries two pairs of barbels, a high sail of a dorsal fin and a deeply forked tail fin. Breeding these catfish is a rare event, which involves a bubblenest, I hear. (There is an article on breeding Hoplosternum thoracatum by Len Rebeck at http://www.fishroom.com.) As they mature, the Dianema females will be larger and broader than the males, but at just under two inches they aren't giving any clues yet. I'm also told that the spiny first ray of the pectoral fins will be thicker in the males.

D. longibarbis were first imported into the U.S. in 1955, according to Wiliam Innes. I don't see them all that often, so I grabbed mine when I had the chance. These mild-tempered social catfish only thrive in the company of their own kind. The first of them were found in the Rio Ampiyacu, which empties into the Amazon at Pevas, Peru, but they are widely distributed in creeks and shorelines of small tributaries of the Amazon, both upstream from Iquitos, whence they are exported, and downstream in the stretch of Amazon between Santarem and Tabatinga, and in the right-bank tributaries Xingú and Pacayá.

The Germans call them "Torpedo Cats." From the forward placement of their mouths, you wouldn't expect them to spend all their time grubbing in the bottom, and they don't. They'll dash to the surface to swallow a mouthful of air like Cories or to eat flakes as happily as they stand on their heads to root out blackworms. Porthole Cats will hold a place in mild current for minutes at a time, or rest motionless, tilted upward, lying on a leaf. An experienced fishkeeper commented to me recently that these are one of the few catfish with forward-facing mouths you can trust with smaller fishes. If mine had horizontal stripes on their tails, they'd be the "other" Dianema, D. urostriata. I see that Dennis Rawlinson describes a spawning of D. urostriata at www.planetcatfish.com. In his first report (Feb 2000) the spawning took place under a floating plastic lid, at pH 6.2, hardness less than 2oGH, and a cool temperature of 68-72oF. Dennis reduced the water depth to 4 or 5 inches. Alas, the first clutch of eggs got eaten.

Loricariidae.

The Loricariids are the world's largest family of catfishes. If you're really together, you're calling these catfish "Lories" now, as the late Al Ngui suggested, so that you can reserve "Pleco" specifically for the Ancistrinae and Hypostominae groups, the ones that include the traditional Ancistrus and Hypostomus genera of armored cats. There are three more divisions of the Lories, Hypoptomatinae, which includes the dwarves, Loricariinae or whiptails, like Farlowella and Sturisoma, and the Neoplecostominae, which have mostly not been imported.

As for "dwarf" Lories, RTR put it succinctly at an AC post, Oct. 2000: "There are no real dwarf plecos. But then there are no real plecos either. Plecostomus was a genus of suckermouth catfish (Loricariids), which is no longer a valid name... smaller suckermouths were imported with no known or even identified scientific name and called "Dwarf Plecos" to distinguish them from the "real" plecos, such as Hypostomus plecostomus (the species name is still valid). The dwarfs are quite different fish, from genera such as Peckoltia and the small Panaque species, most being 3-6" at full maturity. There is no dwarfism involved, merely entirely different fish with a family resemblance to their several times larger cousins."

When your Lories hang on the glass, take a magnifier to see how they are entirely covered with odontodes, the teeth that are embedded in their skin, which are sometimes thickened to produce spines. Even an Otocinclus is covered with tiny prickles.

Links. Jon Armbruster's Loricariid Home Page is the site to scope out if you're curious about any of these Lories. This is one of the best websites devoted to a family of fishes-- scientific but accessible. There's a list of taxa, a key for identification, a phylogenetic tree showing how the various genera are related to each other, all by the taxonomist who is the definitive reviser of these catfishes.

Chætostoma sp. "Recife?" I bought three of these at a little over an inch length, represented to me as an unidentified "Otocinclus species." They were covered with overlapping charcoal gray dots that almost entirely obscured a skim-milk blue-white background which showed on their bellies. It's probably a juvenile coloration. Months later, they still tolerate one another, but they are steadily growing on a constant diet of algae and biofilm, which I supplement with continual spinach and zucchini. Getting a glimpse of them is like bird-watching; it involves long sessions sitting motionless in a darkened living-room.

Links. Shane Linder's notes on the similar "Bulldog" Chaetostoma from Recife, LDA25, are at "Planet Catfish" Their attentuated angled caudal fins always look as if they had been chewed.

Farlowella acus (Common Twig Catfish). Farlowella are ecological end-of-the-line specialist herbivores, like an elongated, extreme Otocinclus. F. acus are widely distributed in the right-bank (southern) tributaries of the Amazon, and further south, in the basin of the Rio Plata. Other Farlowella species take their place in the left-bank, northern Amazon tributaries, and in the Orinoco. The great river is a barrier among these species.

They are delicate and won't last long if you can't give them a lush planting, some well-aged driftwood with a softened algal surface and rich biofilm meadows that you supplement with chopped spinach and zucchini slices. They like the softest water you can muster, some mild current, and shadowy areas where they can make themselves invisible. Leaf litter helps and some twiggy brush. Farlowella need gentle tank companions.

Males and females can be identified with a magnifier while they cling to the aquarium glass. Look at their "noses" (rostra). The females have wider noses that are covered with minute bristles. Male snouts are narrower and bristle-free.

Eventual length is just under six inches.

Hypostomus punctatus (Common Pleco). This is truly a "Plecostomus." That rhymes with "preposterous" by the way, not "PLEEco-STO-mus" the way I was mispronouncing it for years; Mike Wickham says that a $100 suckermouth catfish is a "Plecostoomuch." Hmm, okay.

Hypostomus and Ancistrus species are part of the Ancistrinae subfamily of Loricariids. These are the Lories with the interopercular odontodes, since you asked.

The genus Hypostomus already contains about 116 species, many of them indistinguishable to the amateur. Either Hypostomus punctatus is the most successful, most widely-distributed species of Loricariid in South America, or "Hypostomus punctatus" is actually just a grab-bag name for a cluster of closely-related Hypostomus species. Punctatus is "spotted," and sure enough, they all are! These are not cute little dwarves, at least not forever. If you don't thoughtlessly stunt your Common Pleco by confining it in a tank that's too small, it will slowly grow to a foot long! But ordinarily you'll see it offered at an apparently manageable three inches at the LFS.

Other people seem to get more fun out of their Common Plecos than I do. Mine squirms under an overhanging ledge, rooting out just enough gravel to make a tight fit, and there she spends her days immobile, looking as much like part of the rock as she can. Now I'm searching for some rock that more exactly matches her speckled and splotched yellowish-olive and tobacco brown coloring.

Many Lories rasp at the surfaces of waterlogged wood and depend on wood to supplement their diet. Panaque species are especially noted for this, and some even have spooned chisel-like teeth to help them. Loricariids can be assumed to carry some kinds of co-evolved protozoan and bacterial fauna to digest lignin for them, for no vertebrate can digest lignin, and now J.A. Nelson at Towson U. is unravelling this specialized feeding niche. His illustrated article, "Respiration in wood-eating catfishes" is the best intro to this story. He finds that the breakdown of lignin in Panaque guts is effected by a consortium of microorganisms.

Some insects notorious for eating wood also depend on symbiotic partnerships to break down lignin. Termites are a well-known example, but Cryptocerus wood roaches and passalid bess beetles also make a living chewing splinters of wood and getting the lignin digested for them by intestinal protozoans. Interestingly, all feed their offspring directly from the anus, so that the protozoan community among the wood fibers can colonize the intestines of juvenile insects too. I have a point in mentioning this shared phenomenon. To come back to the aquarium, this suggests a treatment for rehabilitating a half-starved Lory: — give it the company of a plump, well-fed one. In rooting among detritus the two fish are bound to share some beneficial,— perhaps essential— gut protozoa. If they are socially too incompatible, try vacuuming detritus and adding it to the newcomer's tank.

Links. A good Pleco overview is Ingo Seidel's article "Suckermouth catfishes from the Ancistrinae group" at "PlanetCatfish" And you might want to see Dennis Kramb's guide to "Plecos" at theKrib.com

Common Plecos don't need to be kept at the steamy tropical temperatures we tend to provide for them. There are native populations as far north as the Pacific slope of Costa Rica and as far south as the sub-tropical waters of Uruguay. In the USA, feral populations have established themselves in south and central Florida and also in the San Antonio River TX, where they escaped from the Zoological Gardens. In Florida they are proving tolerant of both chilly winter temperatures and brackish water near the mouths of small rivers and canals. Exactly which Hypostomus species are represented in these feral populations has been argued for twenty years. A Pleco fished out of Dade County waters measured 69 centimeters! See http://lionfish.ims.usm.edu/~musweb/nis/Hypostomus_plecostomus.html

Otocinclus spp. Mixed-species stocks of Otos are usually imported, so all the Otos mentioned here are being given their conventional "trade" names. Identifying Otos at the species level depends on professional techniques, like accurate counts of scales along the lateral line, or details of the dentition and the body armor, and symptomatic ratios of one body measurement to another. The details we amateurs might pick out, for instance minute differences in patterning, such as the blotch on their caudal peduncle, are less secure.

One distinction is clear at the species level, anyway. Otocinclus don't have an adipose fin. If your Oto has an adipose fin, it's one of the fourteen species of Parotocinclus. A commonly-seen one is Parotocinclus maculicaudatus, a "Golden Oto" with brown blotches along the lateral line and a larger blotch on the caudal peduncle. The leading rays of dorsal, pectoral or caudal fins are red with brown banding, a feature you might not detect til you get a chance to photograph your Otos.

A specific name is rarely offered at the LFS. Often they are rather arbitrarily offered as O. affinis, O. arnoldi, or O. flexilis, according to the German site "Aquatime" There you are cautioned to pay close attention to which species you have: O arnoldi and O. flexilis have backs and fins peppered with dark flecks of various sizes, with a broken sidestripe. The real O. affinis has a light gray back and a very narrow black stripe, which ends before the tailfin and has no blotch on the caudal peduncle. The website has good pixfor identifying these species, taken from Aquaristik Aktuell. This website makes the point that Otos are happier at room temperatures, yet Paul Kjaerland's Otos spawned at 25°C (77°F). Perhaps cooler "winter" months produce hardier Otocinclus.

My Otos-- the commonest species on the market here in New York-- seem to be either O. macrospilus or O. vittatus. O. macrospilus (Colombia, Ecuador and Peru)is illus at www.planetcatfish.com. There is a shaped band on the tailfin, just inside the clear fin edge. A large blotch on the caudal peduncle. No adipose fin, of course. (The presence of one is a characteristic of Parotocinclus species.)

You know that Otos spend most of their waking lives working their way across algal films. If they have the security of floating plants nearby, they'll even work the underside of the surface film that forms on still waters. It's a lipid layer to which algal cells and bacteria tend to stick, attracting plankton animals. So our little herbivores are getting a more balanced diet than you might think.

Otocinclus have three familiar behavior patterns: they feed, as I described; they do a skittering chaotic scramble that is hard to follow, like a butterfly's unpredictable flight, which could be a handy evasive activity with some practical survival value. And they "freeze." If you've ever seen a cryptically-patterned butterfly come to rest on rough gray bark, fold its wings and virtually disappear, you'll sense how useful it is for an Oto to "freeze" on a slender waterlogged branch, say one about as big around as he is, and similarly disappear. LoMax13, posting from Gainesville FL at AquariaCentral a while ago, had this to say: "What's up with that mad dash thing? It's like they're having a panic attack. They move around like— 'oh crap I can't find enough algae. I'm going to die! Oh...OK here's some more right here. Whew.'" (I just had to pass this on.) Otos will also 'play dead:' Jinlong, Mission Viejo CA, noted:

"When I initially added the otos to the 40g, one of the baby angels decided to suck an oto off the side of the tank. He pulled it off by the dorsal fin! As he did, another angel came up and grabbed the poor oto by the TAIL! The two angels then played tug of war with the poor oto until it flipped loose somehow and fell to the bottom of the tank, where it lay, belly-up. I was convinced it was dead, and apparently so were the angels, who nudged it with their noses for a minute or two before abandoning the toy as no longer interesting. Seconds later, the oto went from "freeze" to "dash" mode and hid behind the heater. Two months later, the same oto is still fat and happy."

"Solo Oto? Oh no! No solo Oto!" Don't keep them solo; they'll "freeze" unhappily under a leaf and pine for reassuring company. A "freezing" Oto may just be resting, or merely too full to feel ambitious. But if there is no other Otocinclus in the vicinity, I think a sole Oto that does an unusual amount of "freezing," is expressing a symptom of unease and tension. It's social stress: "Where is everybody? Why is it so quiet in here? There must be some unseen danger lurking. Better just 'freeze'."

Why newly-arrived Otos can die like flies. Otocinclus are notorious for dying like, well, like Otos,—when you first get them home, though once they've acclimated to your planted tanks they live for years. Aquarists beat themselves up over this, but I think it's not our fault. Here's the thing: no vertebrate vegetarian can digest cellulose, not one! so each carries a species-specific community of anaerobic bacteria (and some protozoans) that do the work. Ruminants even have a special fore-stomach (the rumen) where grass is fermented in a rich bacterial soup, protected from stomach acids. Dairy cows are nourished, not so much by grass, but by bacterial by-products, which include some vitamins, and by digesting some bacteria: cow breath! Now, look at the size of the Oto. Scarcely room for a billion gut bacteria in there to do the work, eh? Starved Otos in transit can lose so much of their gut bacteria that the internal ecosystem doesn't revive,— even with a glut of tasty algae in your tank! It just passes through their system, like when you were too hasty eating that corn-on-the-cob, remember? Not much nutrition when the kernels passed right through, because your system couldn't digest them open. Otos need a jungley tank with lots of leaf surfaces to run over. (If you can count your Otos, you haven't got enough plants.) But the vegetable supplement we give them (zucchini, spinach, etc.) has to be constant, or else they won't have the gut bacteria to process the green treat when it finally does arrive. Hopefully with your algae, and plenty of natural green cover, and your constant feedings of spirulina flakes or algae wafers plus veggies every few days, Otos that aren't too far gone should thrive with you. Females are noticeably wider and plump, but though a healthy male is leaner, he shouldn't have a concave look, when seen from the side.

SegaDojo recently offered the suggestion that Otos might be unusually sensitive to nitrate. That might go far to explain Otos' sensitivity. "As a rule," G. Sterba wrote in 1967 (in Aquarium Care, p. 257) "newly imported wild-caught fish from tropical waters poor in nitrate and nitrite are particularly sensitive."

Breeding. Commercial Otos are still all wild-caught, I believe. Spawning Otos in aquaria is unusual enough to draw attention. Alec in Ontario had Otocinclus spawning for him in 1999:

"although they have not bred in a few months. For a while they were spawning every three weeks or so. My females are about 30-40% larger than the males, at least in the species that I have. There are also subtle structural differences, and the females usually have an extruding vent. I have two females and three males, but they do not pair off. It's basically the female and whatever male manages to fend off the others and get to her first. During the entire spawn, her eggs are usually fertilized at least once by each male. She will go along from leaf to leaf until she finds one she likes. Meanwhile, the males are all jostling along behind her. They will run their mouths along her entire body and position themselves as close as they can to her. When she finds a suitable leaf, she zips underneath it, and the lucky male wraps his body around her snout and holds her in place while she deposits single eggs on the underside of the leaf.

"They consistently produced fry, but I was never able to raise any, and by the time I set up a dedicated fry tank, they had stopped spawning. I am hoping they will resume in the summer again."

Chuck Huffine gave a detailed account of his spawning O. affinis to the Aquatic-Plants Digest. The spawning pair were in a densely-planted 20 gal. without the distractions of other kinds of fish (an important point), though Huffine senses that communal spawning might be more successful. "Oto's seem to be quite territorial despite their small size, and I suspect this fact may be one of the secrets in spawning them, along with water quality and diet. The Otos I keep in community tanks have not spawned, nor have they exhibited spawning behavior to my knowledge despite similar tank conditions. The pair that do spawn live alone with the exception of shrimp," Huffine noted. Weekly water changes with cooler water seemed to encourage spawning behavior. The eggs were carefully placed on a single plant of Bacopa caroliniana and were guarded, a characteristic Loricariid touch. Follow the hyperlink above, for more of the interesting details.

"Attack" Otos. I've never had a "problem" Otocinclus that developed a habit of rasping the body slime off other fishes, but I hear some individuals develop a taste for it. My hunch is that Otos are more inclined to snuffle at the flanks of other fishes in rather sterile environments, when the only available substiture for algae is a Hikari wafer. More natural grazing grounds are spread over all the surfaces of the planted aquarium. When Heinz Bremer and Ulrich Walter examined the nutrition of discus fry, which graze on their parents' slime and on specialized nutritious cells shed intact into the mucus, they found microorganisms, especially diatoms and bacteria, settled in the mucus surface. So the bizarre Oto habit isn't incomprehensible. I think it's mildly aggressive behavior, too; I've seen an Oto that had been repeatedly pestered by another fish, turn on the harasser finally and do some defensive mouthing that was modestly aggressive.

Otocinclus on the web. One of the best Internet articles on Otocinclus is Calilasseia's account, perilously archived in the "Bottom feeder Frenzy" forum at www.FishProfiles.com. Her Otos go under the name of O. arnoldi.

At WetWebMedia.com, Bob Fenner's article "The ideal algae-eater? the littlest South American suckermouth catfishes, genus Otocinclus" gives some of the Web's best pointers for buying Otos and keeping them hale and hearty, mostly from the perspective of the importer/wholesaler, with useful points for picking out healthy stock, handling and acclimating them. He ends with a long list of Oto articles in the print media. Two points that he doesn't mention, which I think are equally important: 1) Otos share gut bacteria: their need for the company of other Otos isn't merely social. And 2) partly because of their need for plentiful oxygen, Otos thrive at room temperature, in the 60s and low 70sF, rather than in the steamy conditionss we are inclined to offer.

Another excellent article, "Otocinclus: 'Little Monkeys' in the Planted Aquarium," by Julian Dignall and Dinyar Lalkaka, outlines recent name changes among Otos, describes some of their natural ecotopes and techniques for acclimating them to the aquarium. It's also archived at PlanetCatfish

Robyn Rhudy's Otocinclus page also has basic details --and some personal experience and further links, too.

...and Parotocinclus too. At "Scotcat.com" you'll find an interesting description of breeding the sister genus, Parotocinclus. But the super Parotocinclus article, full of color photos to compare to your own dwarf Lory is in the section "Ingo's catfish of South America" at www.planetcatfish.com.

Otocinclus cf. affinis. Out of a couple of dozen published species, maybe half a dozen turn up in your LFS from time to time. Compare your mystery Otos first to O. affinis— "Golden Otos," Baensch calls them, and illustrates a very golden one indeed. Whether we have the right species name or not, these are the Otos you see everywhere, and the ones most commonly spawned. They come from southeast Brazil, the area round Rio de Janiero. The specific name is currently a little questionable. Not for us to fret about, though. That "cf." in the name above means "comparable to." It's a cop-out that makes me look less clueless than I am and more like I have some serious scientific reservations about the name I'm using.

O. cf. flexilis. From Rio Grande do Sul, in southernmost Brazil. In this Oto, the black lateral band breaks into blotches towards the tail.

O. cf. vittatus. To about 1.5in. This Oto is from the Mato Grosso of Brazil, and small tributaries in the Paraguay drainage. I have a trio, sold to me as "Giant" Otos! (snicker) Indeed they are slightly bigger than the most familiar Oto, O. affinis. Mine correspond very closely with the photos at "Planetcatfish" where O. vittatus was Catfish of the Month for Dec 1996. O. vittatus features a speckled back on a gray ground, a broader lateral stripe ending in a peduncle blotch, and wavy black lines in the tailfin, with white spots in the base of the upper and lower fin lobes. Paul Kjaerland had some unexpected luck when a small group began laying eggs for him one summer, at a temperature of 25°C and a pH of 7.5, and he got some juveniles out of the resulting fry. Of course you wouldn't keep these or any Otos except in a well-planted tank with a tendancy to grow algae, in peace-loving company, and in water that was soft to moderately soft. Mine get a continual supply of blanched vegetables, a little at a time, and no more till they've finished what they've got. But I don't pull out the spinach leaf after 24 hours; they like it best when it's slimy olive-gray and coming apart. Then they have to forage for algae for 24 hours before they get veggies again. Even the male is mildly plump on this regimen, but I can recognize the female by her broader beam.