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his month we are concentrating on a small member of the Auchenipteridae family, the "Driftwood Cats", and also the small genus Trachelyichthys which comprises of only two individuals, this months choice and also T. decaradiatus. To put you in the picture, the genus Trachelyichthys was created in 1974 by Dr.Mees and in his paper there was only a single specie, Trachelyichthys decaradiatus from the Rupununi River, British Guiana and so T.exilis didn't come along until 1977 where it was described from the Rio Mamon, Peru which is basically on the other side of the South American continent approximately 1,800km away from the first genus discovered. The specimen was caught in a shallow part of the river approximately one metre (39") deep. The substrate consisted of mud and sand. The water was acidic and the surface temperature, 28°c (82°f).

 

 

Trachelyichthys exilis

 

To differentiate between T. exilis and T. decaradiates is sometimes not that easy as they both have the same basic body colouration but the main difference lies in the shape of the humeral process and the positioning of the eyes. Below you can what I mean from the published papers of Greenfield & Glodek, 1977.

 

 

 

In the image below you can see the positioning of the eye in T. exilis.

 

 

The next image below shows T. decaradiates with the rounded humeral process.

 

Trachelyichthys decaradiates

 

Telling the boys from the girls is not too hard in mature specimens as the male shows an extension to the front of its anal fin as is the norm in this family and the female has a normal fin. Below you can see the difference in sexing the genus Tatia which is in the same family. The only difference is the length of the anal fin in T. exils and T. decaradiatus but it does give you an idea and should help you sex out this species if buying from an aquatic outlet.

 

 

 

Pigmy Driftwood

None

Auchenipterinae

South America: Peru, Nanay River basin in upper Amazon River drainage. Type locality: Río Mamón, a tributary of Río Nanay, approximately 25 km west of Iquitos, 3º42'S, 73º16'W, Peru.

9.5cm (3¾ins)

22-25c (71-77f)

Small based dorsal. Large eyes well forward on head. Long pointed humeral process.

Silver tone with black band running over top of body interupted with some spots. Lateral line with large black spots, rest of body with varius spotted pattern. Dorsal spine with black stripe with rest of fins spotted.

Keeping both species is not too much of a problem as long as the water is kept clean and not too alkaline with a p.H.of between 6.5 and 7.0. They do like a planted aquarium where they like to hide during the day. They also make a good show fish if showing your fish at shows is your forte, as they usually deport well in a show tank.

This is a piece taken from the Baench Aquarium Atlas 3 on the breeding of this species: "Well-fed fishes have been known to spawn in aquaria. The male embraces the female so that his genital papilla is very close to the anus of the female. Eggs are fertilised before they are laid among plants; Java moss makes an appropriate spawning substrate" A few members of the Auchenipteridae family have been spawned in the hobby with a successful breeding and raising of the young of Trachelyichthys exilis by Dick Thompson, a former member of The Northern Area Catfish Group (now Catfish Study Group).

Mature specimens, as the male shows an extension to the front of its anal fin as is the norm in this family and the female has a normal fin.

In the aquarium a good mixture of dry food such as flake and tablet. Worm food such as bloodworm, whiteworm and grindal will keep the 'pygmy driftwood' happy in its suroundings.

Trachelyichthys: From the Greek, trachelos, meaning neck, pteron, meaning fin and ichthys, meaning fish.
exilis: Slim or slender, pertaining to the slim humeral process.

Baensch, H.A. and R. Riehl 1991 Aquarien atlas. Bd. 3. Melle: Mergus, Verlag für Natur- und Heimtierkunde, Germany. 1104 p.
Greenfield, D.W. & Glodek, G.S. 1977: Trachelyichthys exilis, a new Species of Catfish from Peru.
Sandford, Mike; CAGB Magazine 41 1984 : Trachelyichthys - two of a kind.

Photo Credits

© Pertti Rassi
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© Julian Dignall @