has a couple of common names - arched cory or skunk cory
and both allude to the black stripe that arches over the
fish’s back from its nose to its tail. Neither of
these names is used much in the hobby however, most being
happy to use its scientific name.
It’s a lovely catfish and
would be top of many enthusiasts’ popularity lists.
Not only is it pretty but C. arcuatus are reasonably
common in pet shops and are not too expensive. For these
reasons it’s a popular and familiar fish and many
fish-keepers have a shoal of these little cats.
First described by M.G. Elwin in 1939 it has been in the
hobby since at least the 1970s so it is a little surprising
that breeding records of this fish are few and far between.
In fact I could find only one documented case, that by
Ian Fuller and described in his book – Breeding
All this being so it was
more in hope than in expectation that I bought a group
of these in 2004 from a local shop and another group of
very young fish from BAS in Bolton the following year.
Over the next few years I tried the usual methods used
to spawn fish of this genus with no success. By the start
of 2008 they were happily, but celibately sharing a 4ft
tank with some C. rabauti, Brochis splendens
and a few Danio margaritatus.
That Spring, when a few eggs appeared
on the glass and on the plants I at first suspected the
brochis. The C. rabauti had spawned once before
and their several hundred eggs had been placed along the
water line. In addition the brochis had been dancing around
the tank and nuzzling each other for a while. In any event
the eggs appeared to be infertile so I didn’t give
it much thought. A further batch of eggs was similarly
ignored although I noted that the eggs were appearing
after a water change. I looked forward to my first brochis
In May 2008 I noticed
some fry – a tiddler which must have been several
weeks old and a couple of fry which were only just free
swimming. They clearly weren’t brochis and a quick
visual check confirmed they weren’t C. rabauti
either. So, unless I had some highly unusual danios
then they could only be young C. arcuatus. My
delight was tempered by the knowledge that so few fry
had been produced. I crossed my fingers and waited for
a further spawning.
Three weeks later, and a couple
of days after a water change, more eggs appeared (I have
yet to witness the actual spawning which I assume
occurs at night). This time I collected those that weren’t
obviously infertile and placed them in an ice cream tub
which I floated in the tank. I added some alder cones
and an air line to try and prevent fungus. The eggs themselves
were scattered around the tank, some stuck to plants and
some to the glass. They weren’t very large as corydoras
eggs go, about the same size as C. panda.
A dozen fry hatched
out four days later. They were small and, looked at from
above, the dark pigmentation on their upper surface made
a T-shape. Their yolk sac was very small so after just
one day I started to feed them on live microworms and
pre-soaked ZM-100 fry food. They all appeared to be eating
fine but I always have trouble rearing small numbers of
fry. I suspect it’s because it’s difficult
to feed such tiny amounts and most of the food is spoilt.
After ten days a couple of the
fry had perished so I made the decision to move them into
a larger tank (18” x 12” x12”) with
a breeding colony of C. pygmaeus and some fry
of both C. concolor and C121. I was due to go
on holiday the first week in July anyway and they would
have to fend for themselves.
This tank is very mature and is
stuffed full of Java moss. I raise handfuls of C.
pygmaeus in it and any other small spawn usually
finds its way in here also. So in they went and off I
went to Center Parcs with the wife and kids.
The lions of Longleat are nice
enough but I’m a fish person myself so I was happy
to be back a week later to check up on the fishy kids.
The C. arcuatus fry are
easy to spot amongst the other species due to two distinctive
spots - one on the lower part of the caudal peduncle,
just where it joins with the caudal fin and one at the
base of the dorsal spine.
As the fry mature these spots merge
into the distinctive black stripe.Happily most of the
young C. arcuatus have survived and I now have
fish from three different spawnings showing the complete
range of patterning from fry to adulthood.
As yet there has been no fourth
breeding attempt (although it’s possible they spawned
whilst I was away) and it could be that this species is
a seasonal breeder. I’ll be keeping a close watch
on them anyway.
The spawning record is
• The tank is a standard
four footer – 48” x 12” x 18”
(L x D x H)
• Internal power filter (Fluval 4)
• Sand substrate with wood, moss and fern for cover
• The light is on 10 hours each day using a timer
• No heater but in this room the temperature won’t
drop below 70F, more normally around 74F.
• pH 6.5 and GH is almost zero (This is my tap water
unaltered). I have a few oyster shells in the tank which
seem to stop the pH drifting down between
water changes but don’t appear to change the measured
• A third of the water is
changed weekly or (more usually) fortnightly with untreated
water straight from the tap. After a water change
the temperature will go down to about 65F.
• Spawning occurs during the night and there is
a four week gap between each spawn.
• Around 30 – 40 eggs scattered on glass and
plants. Fertility seems to be low with only a few from
each spawn being fertile.
• Other fish in tank are Brochis splendens,
C. rabauti and Danio margaritatus.
Of all the fish I’ve bred
over the years this is the most satisfying although, if
I’m being honest, the fish ignored my tinkering
and went about their business on their own terms and in
their own time. Perhaps they just needed some peace and
quiet and be left to themselves for a while, something
we can all relate to!
All images by author
and are copyrighted
Editors note: We
now know (2017) that this species C. arcutaus
is actually a long nosed species, CW036,
and the species in this article is actually C020.
(Grant, S. 2014)