On A Spawning Of Brachyrhamdia imitator, Myers 1927
arly in 1983 in a shipment of Corydoras
melanistius Regan 1912, there was a number of Brachyrhamdia
imitator. The Brachyrhamdia is a naked catfish.
It is found shoaling with the armoured Corydoras
in its native country, the most likely reason for this
behaviour is protection.
After a quarantine period of 10 days in a bare quarantine
tank, the seven Brachyrhamdia were put into a 30
gallon tank set up with biological filters (sub-gravel),
bog wood and tree roots to provide cover and help them
settle down. In the bare, but for a Tetra sponge filter
and small clump of Java Moss, quarantine tank I found
that the Brachyrhamdia proved to be highly nervous
and huddled together under the Java Moss. Even when placed
in the heavily planted and decorated tank they still refused
to come out and swim in the open. To try and give them
the confidence to venture out and about in the open, I
placed 12, 50-75mm Corydoras in with them, 6 of
the C. melanistius melanistius they were imported
with and 6 C. aeneus (Gill 1858). After the addition
of these fish the desired effect was achieved and the
Brachyrhamdia came out of cover to swim with the
Feeding behaviour tended to be frenzied compared to the
toutine style of the Corydoras. Small Poecilia
reticulata, present were left untouched but for the
slow swimming males which were eaten. Young livebearers
which tended to stay just below the water surface were
ignored. All types of food were taken with positive liking
for the meatier foods, fresh prawn and chopped earthworms,
Tubifex, bloodworm, etc. were taken eagerly. Favourite
flake food taken was Tetra Cichlid Flake with its distinctive
One peculiar observation was the Brachyrhamdia
stayed with the C. melanistius types and the C.
aeneus were nipped and driven out of the shoal. The
only reason I could imagine was that the C. aeneus
lacked the distinctive eye mask and shoulder bar and
this made them stand out from the shoal. The C. aeneus
were removed and 8 Corydoras melanistius brevirostris
(Fraser Brunner, 1947) were added. These similarly
marked Corydoras blended in well with the shoal
and were not chased or nipped.
water in the aquarium was around the 6.6 pH mark, hardness
unknown, but local tapwater is quite soft. A week after
the addition of the C. melanistius brevirostris
the Corydoras started to clean plant leaves and
sections of glass.
The first species
to actually spawn was the C. brevirostris they
chose to use the glass sides of the tank to site their
eggs. During the spawning act the Brachyrhamdia
became highly active with the three smaller male specimens
chasing the larger plumper females round into the clump
of densely planted Vallisneria which, in this 15in. deep
tank reached to the surface. Two pairs went through the
motions of spawning amongst the Vallisneria. Observations
of the actual act were made difficult by the speed of
the actual spawning runs, but a side by side method was
employed. Many small transparent eggs were produced which
adhered to the plant leaves. However, these proved to
be infertile. Size was smaller than the average Corydoras
egg but this was made up for in the larger numbers
produced. The trigger factor seemed to be the spawning
of the Corydoras (the sexual emissions from them,
milt, etc.) but further study will see if this is true.
Brachyrhamdia imitator has proved to be a challenging
species to keep and try to breed, but with most catfish
it is the second or third spawning which is the most successful.
I hope to be able to write soon with a more complete account
of successful breeding observations.
This article was originally
in the Catfish Association of Great Britain's magazine No.41.