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Corydoras ambiacus  Cope, 1872

his month we again return to the family Callichthyidae and a request for one of the most misidentified species from this family and one that I must confess has led me to many sleepless nights (how sad is that :-)

There has been a very good paper written on this very subject matter by U.K.aquarist, Steven Grant, and I will not go over too much of the ground that Steve has (scientifically) covered, but suffice to say I will try to attempt to clear up a few misconceptions on this long known Corydoras.


Corydoras ambiacus



The main misidentification centres around a Corydoras that exists sympatrically in some of the same waterways as C. ambiacus and that is Corydoras agassizii, Steindachner, 1876. There is a vast amount of the so-called spotted species that are very much alike but these are the two that are the most erroneously labeled.

Corydoras ambiacus was described by Cope as "slightly concave on the elongate muzzle". In other words our species has a a short snout but elongated upwards towards the end of its snout as in the above picture. Corydoras agassizii tends to have a more rounded snout. As mentioned previously the two species are spotted, C. ambiacus having many small brown spots scattered over its body while C. agassizii has larger spots which basically forms three longitudinal rows of black blotches. Another point is the black blotch to their dorsal fins. C.ambiacus tend to have the blotch on the first three or four rays of the fin and also down into the top half of the body, whereas C. agassizii tends to have it more concentrated on the dorsal fin. You may say to yourself that that is fairly rudimentary evidence, but it is not as easy as that as these two species seem to overlap on colour variations and body shapes and even the Ichthyologists have problems sorting them out, so the jury is still out on them until someone carries out a field trip to collect specimens of these two species, and to facilitate a morphometric and meristic study of them.

Corydoras agassizii
Corydoras cf. agassizii

Above pictures showing Corydoras agassizii on left and Corydoras cf. agassizii on the right.

Acknowledgements: Steven Grant and Ian Fuller for permission to use their photographs.


Dorsal: 1/7: Anal: 1/6: Ventrals: 1/6: Pectorals: 1/9. Form stout, compressed, dorsal line arched, front convex at orbit, slightly concave on the elongate muzzle.

Straw coloured with numerous indefinite brown spots on the sides. Dorsal fin with large black spot covering anterior half, which also expands on the dorsal region round the base of the fin. Four vertical brown bands on caudal fin; anal spotted. Cheeks with blue reflections.

Keeping the Black-spot Catfish is no more difficult than any other of the Northern Amazonia species of Corydoras and it will make a nice addition to your community tank. Keep at least 6 of them, as with most Corydoras they like their own company, then you will find that they will not be so shy and you can see them during the day picking away at any tiny morsel that has been missed by the other occupants of your tank. If you keep Barbs such as the "tiger" keep a close eye on their dorsal fins as this is a waving flag to some of the more nippy species, then you will have to make up your mind to either move your Barbs, or your catfish, to another tank.

Like to lay their eggs (300 or more) in the direct flow of a filter usually high up on the glass where the flow strikes. Eggs will hatch in 3 to 4 days I have not come across any detailed description of the breeding of this species but below is a scenario that you could follow for many of the Corydoras species.

Set them up with preferably more males than females ( a ratio of 2:1 is good ) in a 18" x 12" x 12" tank with either fine gravel or sand with either sponge filter or a corner filter box with a good current. Install some java moss or wool mops, this gives the females a choice of where to place their eggs but you will probably find that they will mostly lay them on the glass anyway.

A temperature in the mid-seventies is good with a p.H around about the neutral (7) mark. Feed a diet of frozen or live food such as bloodworm, whiteworm (sparingly because of the fat content) grindleworm, daphnia and a good quality flake or tablet food.

Make a 50% water change, when you notice the female(s) have fattened up, with water that is cooler so as to bring the temperature down. A good idea is to also add a small internal filter to push the water around the aquarium which will also oxygenate it.

If successful you can either take the adults out and leave the eggs in the main tank or reverse it and take the eggs out by rolling them of the tank sides with your fingers into a small hatching tank, you can then decide to add a anti-fungus remedy or to leave alone. If you make the wrong choice and the eggs fungus you will get another chance as once Corydoras start to breed the first time they will carry on using the afore-mentioned process.

A good quality flake food and tablet food for adults with sparodic feedings of frozen or live food will keep your Corydoras in good health. Feeding the fry after they use up their yolk-sac with brine shrimp naupli, microworm and fry flake food.

Corydoras: Cory = helmeted; doras = leathery skin,(helmeted Doras) cuirass.
ambiacus: After the River Ambiacu, currently spelled Rio Ampiyacu.

Grant, Steven; The variable Corydoras ambiacus, Cope, 1872. Catfish Compendium Vol.1 No.2; Published by D.M.A.Wright, 22 June 2000
Cope, E.D;
1872. On the fishes of the Ambyiacu River. Proc. Acad. Nat. Sci. Phila. v.23: 250-294.
Seus, Werner; Corydoras, The most popular armoured catfishes of South America. Dähne Verlag 1993.

Factsheet Request

Matthew Childers


Photo Credits

1 & 2. - D.M.A.Wright  

3 - © Ian Fuller @CorydorasWorld

Factsheet 081

Corydoras grafi, Corydoras melanistius longirostris.
Common Name:
Black-spot Catfish
Ecuador Ecuador; in the Rio Panayacu, a tributary of the Rio Napo which extends out of the North Western part of Peru and also the Rio Yasuni.
see location map)

Peru Peru; in the Rio Ampiyacu and the Rio Nanay close to the City of Iquitos, capital of the Peruvian Amazonia. Rio Yavari near the village of Benjamin Constant where the three countries of Peru, Colombia and Brazil meet. Rio Tamya around the area of Masisea and a tributary of the Rio Ucayali. (
see location map)
6.5cm. (2½ins)
22-25°C (71-77°F)
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                                                                                                     Factsheet 081= updated December 14, 2018 © ScotCat 1997-2018    Go to Top