Catfish of the Month Right December 2010

Tetranematichthys wallacei
Wallace's Shoe Head Catfish, Driftwood Catfish - Tetranematichthys wallacei   Vari & Ferraris, 2006

Article © Marc Stabel, uploaded November 30, 2010.

With the death of the male specimen, I had no Tetranematichthys left. Within six days my new tank was literally robbed of its three most brilliant inhabitants. I sighed, sat down and thought back.

It all started in the late seventies. More or less by accident I stumbled into a German documentary on South-American fishes, which was broadcast by one of the two(!) Dutch networks. It struck me that some catfishes were shown. At a certain point, a diver scooped up something that looked like a piece of wood. When the camera zoomed in it turned out to be some catfish. But why didn't it move? It kept lying on its side on the diver's hand and didn't budge. Some time later — it can't have been that long, but to me it seemed ages — the fish pulled itself straight and took off in a majestically, quiet way. No rush, no panic. As if it were to say: ”Okay, you have some nice shots for your film now, but I really need my rest so if you'll excuse me I'll lay myself down in a quiet place and please don't disturb me again”. I was absolutely baffled.

But what was it? Even if it had been named in the documentary — which I doubt — I had certainly missed it. And there was very little known in those days. There were hardly any books on catfishes and the internet was still decades away.

As far as I know Tetranematichthys was first mentioned in Burgess' “An Atlas of Freshwater and Marine Catfishes” (1989). There's a drawing with description on pages 285-286. The Japanese Catfishes of the World (1999) had the first pictures (page 115) with a tiny bit of text in Japanese (which I obviously don't understand; moreover, I only obtained that book in 2008). The Mergus series did not include Tetranematichthys until part 6 (2002; page 450). But these future publications were not much use to me in the late seventies.

In the eighties I saw many odd catfishes, mainly through a local wholesaler, but Tetranematichthys was never included in any shipment. Thus my first Auchenipteridae era (1985-1992) contained other eye catchers, like Ageneiosus magoi and Auchenipterichthys punctatus. The only time I saw my all time favourite catfish was on a video as a friend of the wholesaler had a tape of the German documentary. And again I missed the name.

With the arrival of broadband internet (in my case around 2004; and hooray, the phone was no longer constantly engaged) things changed a lot as it became much easier to gather far more information than before. Thus I came across a site called “” which was a German shop that actually stocked Tetranematichthys at the beginning of 2006. After an intense email correspondence a date was set and we (as I'm not very keen on driving long distances alone- we're talking 800 kms here — I had already asked a friend to accompany me) were looking forward to finally obtain some specimens. And then — one can hardly make it up — a friend of my friend died and he had to attend a funeral instead of going to Germany. In all honesty, on that moment I cursed that guy for having to be buried on exactly that date. It goes without saying that in hindsight I'm rather ashamed of my thoughts. I guess I was “too involved” back then.

And there was of course Planet Catfish with a wealth of knowledge and information. And it was through this site that things started to work out. During a visit to Jools and Clare in February 2007, we also visited Neil Woodward at Pier Aquatics. At that time I bought five Trachelyopterus sp. 3 (which are still doing great by the way) and spoke a little with Neil. A little, because he was very busy — as always, as I found out later on. In case you're wondering why I mention this, it's just to make clear that I had met Neil only once when he made an amazing offer.

At the beginning of December 2007 there was a question on the forum from Neil about Tetranematichthys. He had some in from Colombia and was puzzled because the data sheet said they originate from Brazil. I was able to help him out and of course I couldn't resist saying something like: “I wish I could come over and collect some”. To my great surprise and joy there was a reply a few days later saying that Neil had to deliver some fish to Gouda and that if I was interested he would add some Tetranematichthys. If I was interested? I would have crawled to Gouda to obtain them!

To cut a long story short: on Sunday December 23 I collected my trio (1 male, 2 females).  At last — thanks to Neil and Planet Catfish — my 30 years long search was over. I enjoyed them thoroughly. They grew, fed well and showed interesting behaviour. I really liked pointing them out to visitors for they were usually quite visible for auchenipterids. Many of them thought the fishes were dead. Even our neighbours — who always take care of the tanks when we're on holiday and are thus used to erratic behaviour in fishes — once made the mistake of trying to scoop out a perfectly healthy Tetranematichthys thinking it had died. Luckily it swam off, according to the story, decidedly less perturbed than my poor neighbours.

In 2010 I thought my fishes and I could do with a new tank. The front pane of the old one looked like an ice skating rink; I could barely see my animals because of the scratches. I had already postponed this swap for some years and I thought the summer holiday would be the right time. So in July a temporary tank was set up for the fishes, the old one removed, the new tank installed and after two weeks my fishes returned to their new home. Including my Tetranematichthys. After two days I had one dead female, the next died two days later and finally the male died on August 9. Within six days all three of them were gone.

Why? That was the big question. It was so big that when Neil once again reached out a helping hand, I had to say no. But it cost me some time as well as lots of doubts and sleepless nights. After their deaths, I felt the urge of replacing them as soon as possible. It was a bizarre coincidence that Alex (who had helped me enormously) had already left for a three week long holiday to the U.K. and Ireland and had planned to visit Pier on his last day. He was willing to bring fish back to the Netherlands, provided Pier Aquatics had Tetranematichthys in stock. Neil luckily had one pair available (from a different batch than mine) and was willing to reserve them for me. How tempting! Did I need to think about it? No, please do so and bring them along. Only one month without my favourite species; wouldn't that be great?

On second thoughts it was not that simple. There still was the “why?” Also my holiday was coming up and I had no idea how the tank would develop. Just suppose I got back home after two weeks and all fishes would be dead? What would I do with a pair then? Where to put them? It seemed that questions and doubts popped up from everywhere. So in the end I had to tell Neil and Alex to forget about it. As Alex and I had discussed things thoroughly, I knew he would fully agree. But I felt a little reluctant telling it to Neil. I needn't have worried however: he completely understood my (or rather: our) decision.

And that was the end of me keeping Tetranematichthys wallacei. It was August 12, 2010. Two days later my family and I left for France.

The genus Tetranematichthys has long been regarded as monotypic with one single species, namely T. quadrifilis. It was only five years ago that Vari and Ferraris discovered a second species, which they named T. wallacei. As these two species look very much alike, the most important feature for aquarists is that T. quadrifilis originates from a very restricted area (Rio Guaporé) whereas T. wallacei is far more wide spread (Rio Tocantins, Rio Orinoco and several stretches of the Rio Amazon, except Rio Guaporé). It's therefore a safe assumption to say that as good as all imported Tetranematichthys are in fact T. wallacei.

This year a third species was described: T. barthemi (Rio Saracá, Rio Araticum and Rio Urubu). Although difficult to identify on species level, the genus Tetranematichthys can hardly be misidentified in my opinion. They look like brown ageneiosids with a higher neck. These fishes may seem to lack barbels, yet small mandibular and maxillary barbels are present. The latter (upper jaw barbels) are thickened in mature males and probably used when mating (as also can be seen in Trachelyopterus fisheri). Also the dorsal spine in adult males becomes enlarged - to such extent that it looks a bit out of proportion. I actually think the females are much better looking because of their normal dorsal fin and lower neck.

These two features may have given the species its native Peruvian name(-s): Novia bull, Tayta bull and Novia torito (in which “torito” means “small bull”). It is sometimes known to be exported as Leaf fish, but that's a dangerous name: you might end up with Monocirrhus instead. As in all auchenipterid males, Tetranematichthys also have the thickened anal fin tip which is used for internal fertilization. Despite the fact that my specimens were sexually mature, I have never witnessed a mating.

With regard to behaviour this is a very interesting species/genus. I remember that I really had to get used to them. When I collected them in Gouda, the man who took care of them thought they were "spooky" because they didn't move at all. That is what they are supposed to do, I told him, it's their natural behaviour.  I had to agree however that was a strange sight once they were in my tank: while all other fishes were swimming around to grab some food, they just lay there on one side and didn't move. After that first night I found two of them in a different spot, otherwise I would have been worried. It was (and has always been) also very hard to see them breath. A fish you'd like to tap on now and again to see if it still reacted.

What also struck me in the beginning was that Tetranematichthys was apparently not trying to hide. One of them had been lying unguarded against a piece of wood for a whole day and it would have been more likely if it had crept into it - or at least attempted to do so. It was somewhat later that I found out these fishes like to hide themselves into plants, especially large Echindorus (sword plants). A nice advantage and a funny thing at the same time was that I could see them quite well, whereas they probably thought they had blended into the environment and were thus as good as invisible.

There were of course other notable things. These are observations from the beginning of 2008:”very shortly after lights out these fish can be seen hovering near the surface with their barbels pointed upwards. Apparently they skim the surface area in search of food. Contrary to ageneiosids they don't cruise, but swim very calmly. When aware of and/or annoyed by the flash light, they sink themselves until they bump into an object, get on one side and play dead again. They are looking very good. I think they've adapted rather quickly to the tank and don't expect problems with regard to health issues. However, I hope they'll become a bit more visible in the future”. With regard to that last remark I have to admit they didn't.

If you are considering keeping Tetranematichthys, please bear in mind that they absolutely need live feeders from time to time. If you don't want to feed live fishes and/or have no regular and healthy supply I'd suggest you should forget this species to avoid disappointment. I firmly believe that without live feeders this species will eventually starve. Being a gulper catfish, Tetranematichthys will swallow its prey in one piece. They are able to grab fishes the size of a large Gymnocorymbus ternetzi (black skirt tetra). Fishes that are too big for them are absolutely safe. They have a very healthy appetite and tend to be somewhat selfish when it comes to feeding: put ten feeders in and they'll get at least eight of them. They'll inform you of their hunting attempts (and successes) by their splashing and I recall that — especially in the beginning - that sound scared the hell out of me. Imagine me sitting in front of the tank, the whole room pitch black, watching very intensely and all of a sudden it sounds as if my fishes are trying to jump through the glass tank covers. My goodness, that really startled me more than once! But I guess I never belonged to the brave hearted.

It goes without saying that a fish of 20 cms TL (or a little less) needs a roomy tank. Provide shelter (wood and plants) so they are able to hide during the day and see to it that the upper water layer doesn't contain any obstacles. As alas shown in my case, this species is not fond of being handled a lot in a relatively short time, nor does it like a big water change. We (Alex and I, and most likely Neil as well) actually think this combination caused their deaths.

To end this CotM: this catfish could do with some more enthusiastic keepers. You'll have a magnificent fish if you live up to the above made recommendations. So if you ever see them, you are willing to fulfil their needs and you are into odd catfishes, the only thing I can say is: do yourself a big favour. Would I consider keeping Tetranematichthys again? Yes, definitely. But I no longer feel the urge I felt last August.

I take it the reader has noticed the words “too involved” and “urge”. A word I intentionally left out of the above story is ”despair”, but I can tell you that feeling came very, very close last August. And again at the beginning of October 2010, when all my centromochlins died within two days. Despite all the experience involved, these fishes could not be saved. That really hurt. But I think I should accept that these things happen in our hobby, instead of constantly blaming myself.

So I'm no longer hastily chasing fishes. I just don't want to be desperate anymore, as it's apparently not very healthy. I'm quite convinced I will bump into Tetranematichthys sooner or later and then I will once again be the proud owner of my all time favourite catfish. I hope to be able to pick them up at Neil's some day. I don't know when that will be, but I'm certainly looking forward to it.

Copyright information for the images used in this article can be found on the species' full Cat-eLog page.

Down Cat-eLog Data Sheet
Scientific Name Tetranematichthys wallacei  Vari & Ferraris, 2006
Common Names Wallace's Shoe Head Catfish
Driftwood Catfish
Type Locality Upper Rio Negro, São Pedro, mouth of Igarapé do Ibará, about 0°15'S, 66°46'W, Amazonas, Brazil.
Etymology Tetranematichthys: From the Greek tetra, meaning four, nema, meaning filament, and ichthys, meaning fish; in reference to the number of barbels. 
Down Species Information
Size 206mm or 8.1" SL. Find near, nearer or same sized spp.
Identification 1. Lateral margin of head at anterior portion of orbit, parallel to the posterior limit of operculum, in ventral view (Fig. 5a); ventral region light or dark colored; presence or absence of digit-like projections on distal portion of mandibular barbel; length of mandibular barbel 5.2- 2.6% HL; length of main ray of upper caudal-fin lobe 14.5- 20.5% SL; body width at pectoral-fin insertion 82.1- 110.0% HO; head length 24.4- 31.0% SL ..................................................2 1a. Lateral margin of head at anterior portion of orbit, diverging laterally to posterior limit of operculum, in ventral view (Fig. 5b); uniform colour pattern with dark patches along the body; presence of digit-like projections on distal portion of mandibular barbel; length of mandibular barbel 6.3-23.5% HL; length of main ray of upper caudal-fin lobe 18.1-19.9% SL; body width at pectoral-fin insertion 117.0125.0% HO; head length 28.5-32.3% SL ............................................. .............................................................. T. quadrifilis (rio Guaporé Basin) 2. Dorsal region without blurred light area; dark patches of pigmentation present along the body; ventral region dark-coloured; one light coloured stripe present on the caudal-fin; pelvic-fin without distinct light coloured stripe; anterior margin of mandibular barbel with digit-like projections; length of mandibular barbel 7.4-24.6% HL; snout length 41.2-49.3% HL; body width at pectoral-fin insertion 69.279.3% HL ................................................... T. wallacei (rio Tocantins, rio Orinoco and several stretches of the rio Amazon, except rio Guaporé) 2a. Dorsal region with blurred light area; dark patches of pigmentation absent along the body; ventral region light-coloured; two light-coloured stripes present on the caudal fin; pelvic-fin with distinct light coloured stripe; anterior margin of mandibular barbel serrated on distal portion; length of mandibular barbel 4.5-6.0% HL; snout length 28.834.5% HL; body width at pectoral-fin insertion 82.1-88.7% HL..................T. barthemi (rio Saracá, rio Araticum and rio Urubu).
General Remarks This is the species, probably exclusively, but certainly by far the most commonly, imported.
Down Habitat Information
Distribution South America: Rio Tocantins, various locations within the Amazon basin, and the southern and southwestern portions of the Rio Orinoco basin. Reports of T. quadrifilis from the Rio Orinoco system are considered herein to refer to T. wallacei, which is the only member of the genus known to occur in this river basin.
Amazon, Lower Amazon, Tocantins (click on these areas to find other species found there)
Amazon, Middle Amazon (Solimoes), Negro, Upper Negro (click on these areas to find other species found there)
Amazon (click on these areas to find other species found there)
Orinoco (click on these areas to find other species found there)
Amazon, Lower Amazon, Tapajós (click on these areas to find other species found there)

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IUCN Red List Category Least Concern, range map and more is available on the IUCN species page. Last assessed 2020.
Down Husbandry Information
Breeding Unreported.
Breeding Reports There is no breeding report.
Down Further Information
Reference Copeia 2006 (no. 2), pp 169, Figs. 1A, 2, 4.
Registered Keepers There are 7 registered keepers, view all "my cats" data.
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There are 12 records of this fish being seen, view them all.
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Last Update 2020 Sep 29 12:06 (species record created: 2010 Nov 30 13:13)

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