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The fish are housed in a 24 x 12 x 15 tank with swimming pool sand for a substrate and decorated with bogwood and Java moss. The tank like the majority of the tanks in my fish house is filtered by an internal box filter containing gravel and filter wool. One evening in September whilst checking the tanks prior to feeding I noticed an odd egg stuck in the far left hand corner of the tank about two thirds of the way up the glass. As I watched one of the females swam straight up to the egg and ate it! Instant panic. Was I too late or had the rest of the eggs been eaten? fortunately not, on lifting up the clump of Java moss I found forty eggs spread right across the base of the plant. Every egg in the Java moss was as close to the substrate as possible and certainly not more than a couple of millimetres above the sand. Another difference between these two fish is the way in which they spawn. H. adolfoi will normally lay their eggs all over a tank, in the corners, on the sides and all over plants. This broad banded type, it seems only lays its eggs during low runs over the substrate. Apart from the one egg seen to be eaten by a female no other eggs were found other than those in the base of the Java moss. Unfortunately the actual spawning was not witnessed but on every occasion the eggs have always been laid in a similar position. Each egg is 2mm in size and on being removed from the tank were placed into a container containing filtered rain water and a drop of Myxazin. The first eggs started to hatch after four days with the rest hatching on the fifth day. The temperature of the water, in the hatching container being 75 - 76F.

On hatching the fry are large enough, once the egg sac is consumed to take newly hatched brine shrimp. The growth rate of the fry compared to normal adolfoi is far quicker. After four weeks these fry have reached between 12 - 16mm each, far larger than H. adolfoi at the same age. The body marking appears to be the same as the smaller adolfoi, at four weeks their eye patch is already well developed and as well as the body being mottled there are four dark spots spaced between the dorsal and caudal fins which as in adolfoi I'm sure will develop into the black band. The fry are currently fed two to three times a day, either on brine shrimp, flake or chopped Tubifex and if the current growth continues it will not be long before these fry are miniature versions of their parents.

As to where this new fish comes from, I have not been able to find out too much about this, except that I am told that they are collected approximately two hundred miles further up the Rio Negro than H. adoifoi. I have also been told that if two groups of these fish (adolfoi and broad banded) are put in a tank together they will not shoal together but stay apart in two groups. I cannot confirm this as both my groups are kept in separate breeding set ups.

Update:- At nearly six weeks old the fry are still growing fast, the mottling on the body is spreading and the dark spots are enlarging to begin forming the black band.

This Article first appeared in the Catfish Association of Great Britain Newsletter in the fourth issue of 1994.

Ed: Since this article was first produced, the "Broad Banded" Corydoras has now been named as Hoplisoma duplicaroum (previously Corydoras duplicarous).

Update 2024: Lineage: Placed in Lineage 9, the "short-snouted" species with the designated type species: C. punctatus. A revision in the future would constitute the resurrection of the genus name Hoplisoma (Agassiz, 1846).

As of the latest revision (Dias et al 2024) Corydoras duplicarous has now been placed in Lineage 9 and has the new genus name of Hoplisoma and a change to the specific name to duplicaroum.

Photo by the author