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his months factsheet takes me back to my favourite family, the Callichthyidae, namely the Corydoras (now Hoplisoma) genus and a firm favourite for many years in the hobby, the three-lined Corydoras, Hoplisoma trilineatum.

Hoplisoma trilineatum - male

Now these monthly factsheets would not be the same if there wasn't a mystery or two! this month there is no exception. If you visit your local aquarist establishment and you are greeted with a tank labelled, Corydoras julii, (now Hoplisoma julii) you can bet that in 95% of the cases that you will be looking at Hoplisoma trilineatum, unless the shop owner is very much "into" cats and so that will take care of the other 5%!. Why the confusion, well apart from the reason that H. julli hails from Brazil and is rarer and H. trilineatum is found in Peru & Ecuador there is a marked difference in the markings on the area of the snout/head.

Below you can see the comparisons as the H. julii on the top image has a fine spotted head and H. trilineatum below has what you would term, reticulations in that area.

Hoplisoma julii

Hoplisoma trilineatum

Apart from these obvious differences, H. julii is a finer spotted species and not as robust as H. trilineatum. Keeping the "three-lined corydoras" is not that difficult and with most Corydoras/Hoplisoma species will do best kept in a group of six or more as above all they are social animals.

Another Cory that is similar is Brochis leopardus but in this species the longer head is a give-away and is in Lineage 8 sub clade 4.

Update: Corydoras trilineatus is 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 trilineatus has now been placed in Lineage 9 and has the new genus name of Hoplisoma and a change to the specific name to trilineatum.

Three-lined Corydoras

Corydoras episcopi, Corydoras dubius, Corydoras trilineatus

Corydoradinae

South America: Peru, in the tributaries of the Rio Ambyiacu. Ecuador, tributaries of the Rio Napo and the Rio Pastaza.

Male: 5.0cm (2ins) Female: 5.5cm (2¼ins)

24-27°C (75-81°F)

Original description type, locality Peru (Lectotype designed by Nijssen & Isbrücker 1980 ). Holotype size: 40.2mm SL. Dorsal1/7;Anal1/7; 23-24 bony scutes in the upper lateral series, 20-22 in the lower.

This is akin to most of this genus, very peaceful, and would be best housed with small to medium tankmates such as Tetras, Rasboras and Danios or in a species tank for breeding purposes.

As per standard Corydoras/Hoplisoma breeding structures.

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/Hoplisoma start to breed the first time they will carry on using the afore-mentioned process. There are no hard and fast rules to breeding Cory's but the above method works for me and countless other breeders, you may find another method that suits you, as long as you are successful that's what matters.

A good quality flake food and tablet food for adults with sparodic feedings of frozen or live food will keep your Corydoras/Hoplisoma in good health. Feeding the fry after they use up their yolk-sac with brine shrimp naupli, microworm and fry flake food.

Hoplisoma: hóplon, shield or armor; soma, body, referring to bony plates on sides.
trilineatum: Three lined Corydoras.

Alexandrou, Markos & Taylor, Martin. (2011). Evolution, ecology and taxonomy of the Corydoradinae revisited.
Angelica C Dias, Luiz F C Tencatt, Fabio F Roxo, Gabriel de Souza da Costa Silva, Sérgio A Santos, Marcelo R Britto, Martin I Taylor, Claudio Oliveira, Phylogenomic analyses in the complex Neotropical subfamily Corydoradinae (Siluriformes: Callichthyidae) with a new classification based on morphological and molecular data, Zoological Journal of the Linnean Society, 2024;, zlae053.
Fuller, I.A.M. & Evers, H-G: 2005 Identifying Corydoradinae Catfish 384 p.
Ian A. M. Fuller & Hans-Georg Evers (2011). Identifying Corydoradinae Catfish Supplement 1. Ian Fuller Enterprises.
Morris J.T. Catfish Association of Great Britain 1986.
Sterba, Günther. Sterba's Freshwater fishes of the World 1.

Photo Credits

Ian Fuller @