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/A Diversity of Aquatic Life

More Than Corys: The Armored Catfishes of the Family Callichthyidae

By Bob Fenner

Corydoras semiaqilus 

The armored catfishes of the family Callichthyidae are at once distinctive and aquarium-utilitarian, in service for decades as mere "picker-uppers" for all sorts of freshwater aquarium systems. The family comprises some eight  genera of about 171 species (with many more to come if humans can resist destroying them, their South American to Panama habitats...). Modern taxonomic schema divide Callichthyids into two subfamilies (the Corydoradinae with their snout areas compressed or rounded, the genera Brochis and Corydoras; and the Callichthyinae whose members snouts are depressed).

     Their body armor consists of two rows of overlapping plates on either side. Internally, their swim bladders (though they live on the bottom) are encased in bone. They have small, ventral mouths with one, two or three pair of well-developed barbels. A very important, practical characteristic is the presence of a stout spine in the anterior dorsal, pectoral and adipose fins. (painful for sticking in aquarists hands and a real seller of new aquarium nets). 

    These are social animals, that do best kept with members of their own kind... Most losses are due to injury, insults accumulated in collection, holding, shipping.... and secondarily in the lack of proper circumstances in their captive accommodations. Callichthyids need some purposeful feeding of proteinaceous foods, warm waters... Other causes of poor health, lack of reproduction are often water-quality related

Callichthyid Genera: (see www.FishBase.com for a/the most up-to-date taxonomy)


Aspidoras: Sixteen valid species. Look like tubular, elongated Corydoras species. 

Brochis: Three species. Resemble stockier versions of Corydoras spp. 

Brochis multiradiatus (Orces Villagomez 1960), the Long-Nosed Brochis. South America, Ecuador and Peru. To 8 cm. in length. Cond.s: pH 6-7.2, dH to 15. temp. 21-24 C. 

Brochis splendens (Castelnau 1855), the Emerald Catfish. South America, Brazil, Ecuador and Peru. To about 8 cm. in length (females 2 cm. larger). By far the most common member of its genus imported for aquarium use.

Callichthys: Two species, most often seen is Callichthys callichthys. Resemble chunky, drawn-out Dianema/Porthole species with a terminal mouths. 

Callichthys callichthys (Linnaeus 1758), Callichthys Cat or Cascarudo in Sud America. Guianas to Paraguay. To ten inches in length. Cond.s: pH 5.8-8.3, dH up to 30, temp. 18-28 C. Needs a soft substrate, low lighting, meaty foods, TLC on first arrival/acclimation.  

Corydoras: the "super-genus" of the family with some 140 and counting species. Northern South America and Trinidad.

A nice group of Corydoras aeneus (Gill 1858), the Bronze Corydoras. Either as a wild type or albino, the Bronze Cory is a quintessential aquarium catfish. From South America; Trinidad, Venezuela, Brazil. To three inches in length. Best kept in a small grouping. Cond.s: pH 6-8, dH 5-19, temp. 25-28 C. http://fishbase.sinica.edu.tw/Summary/speciesSummary.php?ID=7777&genusname=Corydoras&speciesname=aeneus

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A real "gold" Corydoras... aeneus? IZOO 08.

Corydoras agassizi Steindachner 1876. Agassiz's Corydoras Catfish. South America; Brazil to Peru. To 6.5 cm. Cond.s: pH 6-8, dH 2-25, temp. 22-26 C.  http://fishbase.sinica.edu.tw/Summary/species Summary.php?ID=13109&genusname= Corydoras&speciesname=agassizii

Corydoras melanistius Regan 1912, the Bluespotted Corydoras. South America; widespread, variable species. To 6 cm. Cond.s: pH 6-8, dH 2-25, temp. 22-26 C.  http://fishbase.sinica.edu.tw/Summary/speciesSummary.php?ID=10924&genusname=Corydoras&speciesname=melanistius

Corydoras metae Eigenmann 1914, the Masked Corydoras. South America; found in the Meta River in Columbia. To 5.5cm in length. Cond.s: pH 6-8, dH 2-25, temp. 22-26 C.  http://fishbase.sinica.edu.tw/Summary/species Summary.php?ID=12185&genusname= Corydoras&speciesname=metae

Corydoras paleatus Jenyns 1842, the Peppered Corydoras. Southern Brazil and Argentina. To 7 cm. total length. Cond.s: pH 6-8, dH 5-19, temp. 18-23 C.  http://fishbase.sinica.edu.tw/Summary/species Summary.php?ID=10926&genusname= Corydoras&speciesname=paleatus

Corydoras pygmaeus Knaack 1966, the Pygmy Corydoras. South America: Madeira River basin. To 2.1 cm. total length. Natural Cond.s: pH 6-8, dH 2-25, temp. 22-26 C. Aquarium photo. http://fishbase.sinica.edu.tw/Summary/speciesSummary.php?ID=12194&genusname=Corydoras&speciesname=pygmaeus

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Corydoras sterbai Knaack 1962. To 6.8 cm. South America: central Brazil and Bolivia. Aquarium photo. http://fishbase.org/Summary/species Summary.php?ID=46235&genusname =Corydoras& speciesname=sterbai

Dianema: Two species, Amazonian. 

Dianema urostriatum Cope 1872, the Porthole Catfish. South America; Brazil. Males to 8 cm., females to 12cm. Cond.s: pH range: 5.5 - 7.5; dH range: 2 - 20. Temp. 25-28 C. A perennial favorite, and hardy if received in decent health and acclimated. The "regular" Porthole lacks the Flagtail's caudal striations.

Dianema urostriatum (Mirando-Ribiero 1912), the Flagtail Porthole Catfish. South America; Brazil. Males to 9 cm., females to 12cm. Cond.s: pH 6-8, dH 9-16. Temp. 25-28 C. A perennial favorite, and hardy if received in decent health and acclimated. The congener, the "regular" Porthole, Dianema longibarbus lacks the Flagtail's caudal striations. 

Hoplosternum: Three (current) species. Some of this genus' members have recently been moved to the genera below.

Hoplosternum thoracatum

See Megalechis below

Lepthoplosternum: Four species previously listed as Hoplosternum.

Megalechis: Two species of former "Hoplo's".

Megalechis (Hoplosternum) thoracata (Valenciennes 1840), the Spotted Hoplo. Eastern side of Andes, South America. Conds.: pH 6-8, dH 5-19, temp. 18-28 C. Here are a tank bred juvenile and an adult in captivity. 

Scleromystax: http://en.wikipedia.org/wiki/Scleromystax

Scleromystax (Corydoras) barbatus (Quoy & Gaimard 1824), the Banded Corydoras. Southern Brazil. One of the larger members of the genus, attaining nearly five inches in length. Conds. pH 6-8, dH 2-25, temp. 25-28 C. Pic by NealeM at right. http://fishbase.sinica.edu.tw/Summary/species Summary.php?ID=12161&genusname= Scleromystax&speciesname=barbatus
Not a great photo of a beautiful species: Female shown below.

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    Of healthy stocks is number one critical with this family, especially the genera other than Brochis and Corydoras (though these have their problem species, conditions too). Many Callichthyids are lost due to the vagaries of harsh collection, handling and shipping... For an importer of large numbers of these fishes, or a specialist trying new, expensive stocks I offer my input for reducing initial mortality: On arrival, match the temperature, pH, of the shipping water, slowly (as in a drip line) replace all the water a few volumes if time allows with new, overflowing to waste... Once ammonia is undetectable (yes, this may take hours), change out all the water at once by carefully grasping the bag at the top and pouring out the liquid (leaving the Cats in the bag so to speak). Place them in a tank of adequate volume (enough space for all to settle on the bottom), and add 3-4 teaspoons of non-iodized salt per ten gallons of seawater (Yes, I'm aware that these fishes live in nearly sodium free waters in the wild). Add a double dosage of malachite green and a triple dosage of methylene blue and a couple of airstones for circulation and aeration. A few (four to six) hours later, change out eighty percent of the water, replenishing the salt/water removed with new. Continue to change half the water out daily, more frequently should ammonia approach 1.0 ppm. If you have large losses within a day, dose the system with one mil per ten gallons of 37% formaldehyde (increase aeration), and change out the water as before (80% after 4-6 hours have passed).

    For "end-users" (hobbyists) I STRONGLY encourage the timely waiting of a good two weeks before purchasing any "newly arrived" Callichthyids at your dealers... This time span will allow for "mysterious losses" including improper handling/acclimation and the possibility of parasite-losses from wild-collected specimens. Perhaps it should go without stating (here I go) that captive produced specimens are vastly superior. Can't tell if the ones offered are wild/tank-raised? Ask your dealer... they don't know? Get thee to other sources. Also, look at the top of the animals' heads... wild ones very often bear the scars, rub-marks from captivity/shipping.

Collecting Your Own:

    Can be done rather handily if you happen to be most anywhere in South America or Trinidad. Do some investigating into the law of the land you're traveling to, read in the hobby magazines how others have "done it", and pack up suitable clothing, nets, bug-spray... 

Environmental: Conditions



    Though often found in slow to no moving waters/drying pools in the wild, Callichthyids revel in medium to brisk waters in captivity. Additionally a soft, smaller diameter "more spherical" substrate (not flat and sharp like silica or volcanic rock/sand.) sand bottom suits them. You will often find newly-imported and mis-kept specimens with bloody, petecchial markings on their undersides... much of this is due to rough handling, appalling shipping conditions, but just as well, coarse substrate and unsuitable water quality can produce the same result. 




   Armored Callichthyid cats need clean water of low metabolite load to be healthy, at their appearance, reproductive best. For the whole family temperature tolerance/preference spans 10-32 C. (about 50-90F.), but you will have to do some investigating here by species. Slightly acidic to alkaline waters (about pH 6-8) are fine for most, barely acid to neutral being ideal for many. Hardness of their waters can be of critical importance in acclimating/saving fresh imports... and inducing spawning, preserving gametes and young. Many aquarists simply keep their South American Catfishes in too-hard water.

    Understand the basics of water chemistry and physics, meet these fishes halfway in their requirements, desires, and you will have them for years in good health. 




    Needs to be complete (mechanical/physical, biological and chemical), with added aeration for the species that are bubble-nest breeders. Outside power filters are favored over in-tank types as these are easier to maintain, and manipulate for periodic addition of activated carbon. The trusty undergravel filter can be a nuisance here, with softer waters losing pH rapidly right on the bottom where these demersal fishes live. Do regular water changes with gravel-vacuuming if you utilize U/G or not. 




    It's a shame that there has been such a profusion of popularity with "desk-top" aquariums. Such tiny volumes deny you of much needed stability in providing tolerable conditions for your aquatic charges. What's more, with fishes like the Callichthyids, much essential exercise area and chance to observe shoaling behavior is lost. The smallest volumes the tiniest species should be housed in is ten gallons IMO, and several times that for the larger ones. As with all animals, the larger the habitat, the better. 


Callichthyids do not enjoy (or experience in nature) bright light. Subdued arrangements are best provided with the use of live plants (plastic if not), with some drift wood, rock work adding relief and play spaces. Make sure that all these hiding/play spaces are wide enough to allow the Callichthyids to get out easily. Many fishes are lost each year to getting stuck in "castles" and such. 


       About jumping out. They can... though these armored cats look like miniature tanks (they are), they're more than capable of launching themselves out of uncovered systems... keep your top completely covered. And, should you prove remiss in this duty, don't necessarily toss out that partly dehydrated specimen, do place it back in system water... as these fishes are slow to dry out to the point of death. 






    Tankmates for this family's members are easy to find. They are generally benign to all but the smallest, slowest fishes, and do not actively seek out fishes as food. Reciprocally, due to their body armor, leading spines on fins, they're generally left alone by most all predaceous fishes... however, beware of mis-matching them with very large fish-eating fishes, particularly ones that come from waters in non-native waters.

    The fact that most are actively shoaling social species cannot be overly emphasized. In the wild, Callichthyids are invariably found in groupings of their own species, and are a joy to behold kept this way in aquariums. 




    Putting in new Callichthyids is easy enough. Researching the commonly kept species can be done in books, the internet, and aiming for something within their range of water conditions is fine... with either a drip acclimation protocol or water mixing approach. 


Regarding Handling:  


    As has been mentioned these fishes possess substantial fin spines in their dorsal, pectoral and adipose fin anteriors. Substantial, and painful to get punctured by... The pectoral fins can be locked into position and along with the dorsal very frequently get hung up in aquarium netting when moving Callichthyids... You can likely avoid the hassle of cutting up your nets (don't pull on the fish!), by either using a net to guide the intended catch into a plastic specimen container underwater, or by utilizing a very fine meshed net (like the ones used for straining out baby brine shrimp). Learned, practiced folks in the trade even use just their bare hands.

    One other pertinent note for folks in the industry re handling these fishes, concerning their ancillary (branchial and intestinal) breathing mechanisms. Like labyrinth fishes (e.g. the Gouramis), the Callichthyids should be "bagged" with half oxygen (at most) as they will damage themselves from breathing a too-rich mixture if sealed in pure oxygen and water.

Predator/Prey Relations


    Only the smallest of fish fry and young are of interest to Callichthyid Catfishes as food. Conversely, only the meanest and/or dumbest of predatory piscivorous fishes will try to eat them (though I have seen more than one co-mortality of an erstwhile Cory eater dead with a couple of puncture wounds abdominally). 




    Of the many interesting notes that might be offered, the fact that many of these fishes are aerial respirators, even short-distance land-travelers should be mentioned. Portions of the gastro-intestinal apparatus are useful as ancillary breathing apparatus, and you will find yours making periodic forays to the surface to

 gasp in air. In times of need, they can/do utilize this ability and pectoral spines to inch-along to deeper water in the wild.


Reproduction, Sexual Differentiation/Growing Your Own:


    Many species of this family have been successfully bred and their young reared in captivity. Sexing is easy with most. A view from above reveals "beamier" females, particularly wider at the junction of their pectoral fins and the body. Longer unpaired fins, differences in markings are obvious sexual differences in some species as well, particularly near/during breeding condition. Hoplo's can be sexually differentiated on the basis of their body plates on the undersides of their bodies. If you can get a very close look, these fishes' anal pores are often different, with the females being larger, more blunt during egg laying. 


    Members of the genera Callichthys, Cataphractops, Dianema and Hoplosternum are bubble-nest builders, making their own spawning sites just under the surface with a mix of bubbles of air, plant parts and detritus and a mouth secretion, usually by the male. Females form a ball of eggs which are fertilized and swims them up into the nest. Both parents guard the eggs, developing young for about four weeks.


    Aspidoras species are somewhat "intermediates" in laying their eggs in plants or tank sides in captivity with more than one male involved.


     Egg layers  (Corydoras, Brochis) are group-spawners, with hobbyists using two or three males per ripe female.  Adhesive eggs are laid and fertilized by all in a type of elaborate swim/dance. There is no parental care afterward, with some spawners eating their own eggs if not separated. Hence, some culturists remove the parents, others their fertilized eggs and treat them variously to ensure development. Young hatch out in 3-5 days depending on species/conditions, and absorb their egg sacs in 2-3 days after. 


    Many writers/breeders endorse ideas like conditioning spawners with copious feedings (small amounts more frequently), changing half the water with pre-made, elevating or lowering  temperature... and water depth (to more shallow) to induce spawning behavior... given good conditions, enough individuals most all species will spawn in captivity. 

    Much good information on individual species reproduction, husbandry is to be found in hobbyist literature. See the scant bibliography below as an introduction. There is need for a steady supply of these fishes in the ornamental hobby, and I know of several people who "support their pet-fish habit" with their culture.


Feeding/Foods/Nutrition: Types, Frequency, Amount, Wastes


    Corydoras et al. are more carnivorous than omnivores... eating mainly insect larvae, worms, and crustaceans in the wild. Do bear this in mind, and don't simply treat these fishes as "scavengers", or happy with what dried, flake foods may fall their way. They will not prosper. Give them at least twice daily meaty foods that you are sure are getting to them. Fresh, frozen/defrosted, pelleted, freeze-dried formats are available which serve this purpose. 


Disease: Infectious, Parasitic, Nutritional, Genetic, Social


    Callichthyid Cats are host to numerous worm group, protozoan and infectious agents as new imports, and should go through at minimum, a two week preventative treatment/quarantine period before further distribution. As aquarist's holdings these fishes, though armored are definitely susceptible to "Ich" and other parasitic and microbial disease. Without exception, their susceptibility to such assaults in environmentally linked. That is, poor and/or unsuitable water conditions, lack of nutrition are at base in their loss of vitality, likelihood of loss from indirect pathogenic disease.

    As a group they are treatable with commonly employed medicants, including salts. 




    As a brief introduction to this family, a testament to their beauty and utility, attempt to dispel rumors re their care, encouragement to have you try their keeping, breeding, I hope that this will be some catalyst to your better consideration/appreciation of these fine fishes. We need just these sorts of "small reminders" of the aquatic parts of South America to chide our understanding of what can be lost there, and what can be gained and preserved in our care. 

Bibliography/Further Reading:


Catfishes on the Internet:



Planet Catfish: http://www.planetcatfish.com/core/index.htm

Catalogue of the Callichthyidae: http://www.pucrs.br/museu/callichthyidae/callicat.htm

Corydoras: http://www.effect.net.au/s.alasya/Cory.html

Axelrod, Herbert R. 1965. Having trouble identifying Corydoras? TFH 3/65.

Burgess, Warren E. 1982. Corydoras & Co., pts.1-3. TFH 7,8,10/82. 

Burgess, Warren E. 1989. An Atlas of Freshwater and Marine Catfishes. Tropical Fish Hobbyist Publications. NJ, USA. pp. 786.

Burgess, Warren E. 1997. Corydoras coriatae, a new species of Callichthyid Catfish related to Corydoras fowleri. TFH 4/97.

Chefalo, Pat. 1995. Hoplo mad! FAMA 4/95.

Edwardes, Mike. 2000. The Corydoras conundrum. On a revised taxonomy of the Genus Corydoras. TFH 6/2000. 

Falcione, Peter. 1991. On Fish: A very good question (on preventing losses, treatment of Corydoras from the wild) Pets Supplies Marketing. 4/91.

Finley, Lee. 1982. Brochis multiradiatus (Orces-Villagomez), the Long Nosed Brochis. FAMA 11/82.

Finley, Lee. 1995. Covering Corys. The aquarium literature on catfish continues to increase. AFM 2/95.

Finley, Lee. 1996. Brochis multiradiatus, the Long-nosed Brochis. TFH 3/96.

Finley, Lee. 1996. A new look at Brachyrhamdia. TFH 5/96.

Finley, Lee. 1997. On the Corydoras species described in aquarium literature. An annotated list. TFH 6/97.

Fuller, Ian. 1983. Spawning Corydoras barbatus (Quoy & Gaimard 1824). FAMA 12/83.

Glass, Spencer. 1997. Keeping and spawning Corydoras panda. TFH 7/97. 

Goldstein, Robert J. 1991. Breeding the Callichthyid catfishes. AFM 10/91.

Gosline, William A. 1940. A revision of the neotropical Catfishes of the family Callichthyidae. Stanford Ich. Bull. v.2, no.1, pp.1-29.

Gypser, Klaus-Henning. 1978. Rarely encountered- Corydoras pygmaeus and C. hastatus. Aquarium Digest International 3(1978), #21.

Howe, Jeffrey C. 1994. Original Descriptions: Corydoras breei Isbrucker and Njissen 1992. FAMA 7/94.

Jockel, Silvan. Undated. The amazing spawning behaviour of the Pygmy Corydoras, Corydoras pygmaeus. Aquarium Digest International #37.

Johnson, Don S. 1985. The curious Corys and their kin. FAMA 10/85.

Kahl, Burkard. 1972. Armored Catfishes. Aquarium Digest International 1:1, 72.

Langhammer, James K. 1988. The miniature Corydoras Catfishes. GDAS (hobbyist bull.) 4/88.

Maurus, Walt. 1992. The Piscatorial Verbiphile. The Family Callichthyidae. FAMA 2/92.

Nelson, Joseph. 1994. Fishes of the World, 3d ed. John Wiley & Sons, the World. pp.600.

Njissen, H and I.J.H. Isbrucker. 1976. A new Callichthyid Catfish, Corydoras gracilis, from Brazil. (Pisces, Siluriformes, Callichthyidae). TFH 9/76. 

Padovani, Gian. 1986. The collectable Corydoras, pts. 1,2. FAMA 9,10/86. 

Pinkerton, Alan. 1987. Corydoras habrosus- A dwarf species from Venezuela. An in-depth account of the spawning of an attractive dwarf Corydoras. TFH 2/87.

Pinkerton, Alan. 1988. Breeding Corydoras haraldschultzi. TFH 8/88.

Repanes, Nick and Marcia. 1978. Spawning the Albino Corydoras. FAMA 2/78.

Sands, David. 1979. Corydoras: Neglected by never alone. FAMA 2/79. 

Sands, David. 1988. The challenge of breeding Brochis. TFH 7/88.

Sands, David Dean. 1989. Family Callichthyidae, seven parts. FAMA 1/89-5/90

Sands, David 1992. Corydoras aquarium hybridization. A discussion based on the cross-breeding of two catfishes from Colombia and Brazil by Jim and Christine Wylie of Scotland. FAMA 1/92.

Sands, David. 1995. Four new Corydoras (Callichthyidae) species from Upper Negro River tributaries and a range extension with a discussion of C. bicolor Njissen & Isbrucker. FAMA 5/95.

Sands, David. 1999. Genetics in Corydoras, a review of existing literature. Introduction, pts. 1-3 . TFH 1-3/99.

Schreiber, Roland. 1994. The king of the Corys, Corydoras barbatus. TFH. 10/94.

Stanco, Philip. Breed a Cory. Corydoras species are among the most rewarding small catfishes available to the hobbyist. The author outlines a sure-fire program for successful breeding of these little scavengers. TFH 12/87.

Tavares, Iggy. 1998. The Bronze Catfish. FAMA 11/98.

Vires, Larry. 1998. Those captivating Corydoras. Breeding them is easier when you know what you need. AFM 7/98. 

Volkart, Bill. 1989. Breeding the Corydoras Cats. FAMA 3/89.

Wheeler, Stu. 1978. Panzerwels and paleatus. The Catfish family Callichthyidae. FAMA 2/78.

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