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Dianema urostriatum  (Miranda-Ribeiro, 1912)                                          

here are only two species in the genus Dianema, the other being longibarbis, the Porthole cat. This is of course the Flagtail cat as looking at the image you can see this trait in the caudal fin, it shares these unusual markings along with Corydoras robineae, it is also placed in the same family, Callichthyidae.

Dianema urostriatum
Dianema urostriatum

In body shape it looks like an elongated Corydoras with quite large eyes placed laterally, and possessing four pairs of barbels and a deeply forked caudal fin.

To tell the males from females is not easy but the hard rays in the males pectoral fins tend to be a little thicker than the females. As a show fish they tend to fold their caudal fin when placed in  a show tank and they never seem too happy in the confined quarters.

On my collecting trip to Iquitos, Peru in 2000 I collected the other Dianema (longibarbis) so these only two species from the same genus are very many miles apart and so I find it strange that they are so alike, apart from the caudal fin, where longibarbis has no markings at all.

Head depressed, width much less than the depth of the body. The fontanel is elongate and the supraoccipital does not form a backward projection. The suborbital is very narrow and naked and the nuchal plates fuse along the midline between the supraoccipital and the dorsal. The abdomen between the pectoral fin bases is usually completely covered by the expansion of the coracoids. There is no azygous predorsal plate. The eyes are large and lateral in position. The lower lip has two to four pairs of short barbel-like flaps in addition to the rictal barbels; the rictal barbels extend to the pectoral fin origin or beyond. The dorsal fin has a spine and 7 or 8 soft rays, its base length contained 1 to 1½ times in its distance from the adipose fin. The caudal fin is forked.

Ground colour of head and body grey/brown, upper half of body covered with small black spots, which can vary in number. Lower half of body silvery grey. Caudal fin is strikingly marked with black and white stripes. Remaining fins pale tan.

This is a peaceful midwater to bottom swimmer that will do better if kept in a group of at least 4 as individuals on their own tend to sulk and never seem to progress too well. Try to resist placing them in an aquarium with aggressive species such as some Cichlids, they will do better with the usual community type fish and of course along with Corydoras sp.

This fish has proved a challenge for quite a few catfish enthusiasts, including myself, over the years. There has been unconfirmed reports of breeding triumphs but no documentation as yet to prove this theory. It is reported to be a bubblenest breeder just like its cousins in the Hoplo/Megalechis/Lepthoplosternum-complex.

Omnivorous, taking most foods but preferring live and frozen such as daphnia, worms, white and grindal, and bloodworms. Will also accept good quality flake and tablet foods.

Dianema: Dia = through; nema = thread. The gender of this name is neuter, not feminine as usually thought.

Riehl, R. and H.A. Baensch 1987 Aquarien Atlas. Band. 1. Melle: Mergus, Verlag für Natur- und Heimtierkunde, Germany. 992 p.
Burgess, W.E. 1989 An atlas of freshwater and marine catfishes. A preliminary survey of the Siluriformes. T.F.H. Publications, Inc., Neptune City, New Jersey (USA). 784 p. 

Photo Credits
Left picture:   Helen Burns
Right picture: © Danny Blundell @ The Danny Blundell Photo Gallery  

Factsheet 029

Decapogon urostriatum
Common Name:
Flagtail Catfish
Brazil Brazil: Amazon River basin. Type locality: Manáos, Brazil.   
11.5cm (4½ins)
22-26°C (71-79°F)
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                                                                                                                                              Factsheet 029= updated June 6, 2005 © ScotCat 1997-2018  Go to Top