ver a number of years I have collected
specimens of my favourite Corydoras - C. metae.
My best fish were found at Arbroath in June 1981. These
were in excellent condition, having no signs of shipping
damage and I purchased six which quickly settled in.
My original seven C. metae (which I had collected
over the past year or two) had been conditioned and
set up in a 60cm x 30cm x 30cm tank. This tank was furnished
with Java Fern and some plastic plants and had 25mm
of Dorset pea gravel for the substrate. The tank was
not illuminated, the pH 7.2, and temperature 75°F.
Both sexes were present, four large females and three
males. They had previously spawned in September 1980
and the eggs hatched but the fry failed to absorb the
yolk sac and they had not spawned since. These fish
had been set up for a number of weeks when the new
C. metae were purchased.
The new stock, nearly all males and smaller than members
of the original colony, were housed in the Corydoras
stock tank. By late August all the new C. metae
were looking really good. Three males were seen pursuing
one fish around the 100cm tank. Perhaps this was a female,
but there was no sexual characteristic visible. I decided
it was time to move the six smaller fish (now 38mm)
to the breeding tank containing the original C. metae
(which still had not spawned).
After a few weeks in the breeding tank, three small
males were seen following a large female. This did not
seem to be the start of spawning, as the fish were leisurely
compared with the normal spawning behavior of other
Corydoras. At feeding time on the following evening
a large egg was seen attached to the leaf of a plastic
plant. On closer examination, more large eggs were found
individually attached to the roots of the Java Fern
and on some leaves of the plastic plants. The plants
and eggs were removed to a 25cm x 15cm x 10cm tank filled
with half fresh and half spawning water, with some gravel
and a sponge filter.
After five days at a temperature
of 75°F, twelve eggs hatched (eight had been removed
after fungusing). Liquifry was added to the tank on
the second day and thereafter brine shrimp, micro worm
and prepared fry food were fed regularly. Despite an
abundance of these foods the fry did not appear to be
getting any nourishment. Their stomachs did not seem
to be full at any time and they started dying after
three days. By the third week only eight fry survived,
but all were looking much healthier, with full stomachs.
During this critical period the bottom of the tank was
siphoned every day and topped up with aged water of
the same temperature. This kept the tank very clean.
Again the males were showing interest in the females
and this time I watched closely. It was late evening
and three males followed one female around the tank.
Again no typical Corydoras spawning activity
occurred. The female took up the characteristic 'T'
position with a male, placing her barbels close to the
male's ventral area. A single egg was released and she
lazily swam away to place the egg on the roots of the
Java Fern. The spawning was very haphazard and only
five eggs were laid -one at a time, and placed on the
roots. Next day thirty eggs had been laid on the roots
of the Java Fern. The plants and eggs were removed as
Again, I had the same difficulty
feeding the fry. By the end of the first week ten fry
had died, no matter what was fed (including liquefied
spinach) their stomachs was never full. It was not until
the fourth week that the deaths stopped. The growth
of the twelve fry was very slow, but at six weeks they
were moved to the tank containing the first spawning
of C.metae, which were now twelve weeks old.
Both spawnings continued to grow and to date all are
the same size.
Since then, there has been a spawning of 100 eggs (possibly
a flock spawning), 75% of which were fertile. The same
procedure was followed and again heavy losses occurred
during the first week. After discussion with other breeders
I stopped feeding newly hatched brine shrimp and deaths
ceased the next day.
The fry are now on a mixed diet excluding brine shrimp
- growth is still very slow, but it is hoped that a
higher percentage will reach maturity. This experience
would seem to indicate that the fry of C.metae are intolerant
of the salt content in newly hatched brine shrimp.
This article first appeared
in the Catfish Association of Great Britain Newsletter