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.
The main misidentification centres around
a Corydoras that exists sympatrically in some of the
same waterways as C. ambiacus and that is Corydoras
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.
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
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
Grant, Steven; The variable Corydoras
ambiacus, Cope, 1872. Catfish Compendium Vol.1 No.2;
Published by D.M.A.Wright, 22 June 2000
= helmeted; doras
= leathery skin,(helmeted Doras) cuirass.
ambiacus: After the River Ambiacu,
currently spelled Rio Ampiyacu.
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.
1 & 2. - D.M.A.Wright
3 - ©
Ian Fuller @