Article © Wolfgang Ros, uploaded May 02, 2011.

German aquarist Wolfgang Ros introduces this sleek, svelte and striking predator catfish - its behaviour has clearly made a lasting impact on its keeper. The photo above is the author's, nearly adult, specimen resting at his favourite spot. At the time this fish was approximately 35 centimetres in total length.

Aguarunichthys torosus is an agile and fearless hunter for the predatory aquarium. A medium-sized catfish with attractive colouration and a slim, streamlined body. During feeding it throws caution to the wind. Persistently it chases off again older, stockier cichlids also interested in grabbing chunks of food. In particular, it is feeding time that promises interesting and exciting observation. Otherwise, however, the catfish usually rests and then gives their observer the impression of a somewhat timid “pretty boy”. But with this species that first impression is deceptive!

The genus Aguarunichthys belongs to the Antenna Catfish family (Pimelodidae). The genus includes - besides the sporadically imported A. torosus - two other species which are rare even in nature and therefore are imported even more rarely. A. inpai which with 42 centimetres SL is the biggest and A. tocantinsensis which remains at nearly 32 centimetres SL a bit smaller than A. torosus whose SL in nature is specified with approximately 35 centimetres. All three have a characteristic pattern of black dots on a lighter background. The spots vary in number and size depending on the species. Particularly striking is a light zone which is a little forward of the middle of the body and which extends obliquely to the rear in the form of a strip from the back approximately to the beginning of the pectoral and ventral fins. Young specimens of A. torosus are more brightly coloured but like adults already show the typical stippling. The Latin "torosus" means "muscular" and describes the species well. For this catfish seems to be in good shape and does not seem to have too many grams of fat on his body. At it probably also linked the German name "Stier-Antennenwels", or Bull Antenna Catfish.

In form and patterning A. torosus is reminiscent of another, however a good one-third larger, South American catfish, namely Calophysus macropterus, which is comparatively more common in the trade. Unlike the former A. torosus is spotted nearly to the underside of the abdomen; also it lacks almost all of the bluish sheen that, especially for adult C. macropterus, is characteristic.

The species is not one of the fast-growing predatory catfish. Although a specimen of 10cm in length is capable of doubling its body size in about a year, after that however it needs still a good two to three years to reach its maximum total length in the aquarium of usually little more than 35 centimetres. Therefore A. torosus, unlike many other larger Pimelodidae, can be kept responsibly by a wider group of predatory catfish fans.

Moving at speed

Acquisition & Husbandry
Aguarunichthys torosus is often regarded as a delicate species. That is especially thought of newly imported young specimens of ten centimetres or smaller that sometimes die after a short time of a mysterious skin disease that is barely kept under control with medication. Although it is much more expensive, it is better to acquire animals from a length of about 20 centimetres. These should also be kept for some time by the seller. This means you can be quite certain that for the significant price of about 100 to 150 Euros you have a long lived acquisition. If the catfish has acclimated to his new home, its care turns out to be not as particularly difficult if some fundamental rules are respected. Adult specimens at least should not keep in tanks smaller than 2m long with a minimum width of 70 centimetres. If the aquarium occupied is too small, the danger is greater that the catfish takes fright at, for example, a sudden movement outside or maintenance inside in the aquarium. If so, it will abruptly spurt to the surface and even jump out of the water. The temperature should be 23 to 26 degrees Celsius and the pH is ideally located between 6 to 7. Weekly partial water change is recommended. A tip, according to their river of origin the species needs a lot of oxygen; so the keeper should provide for a stronger flow and additional aeration. Then the fish feels better and visibly demonstrates this in a more active lifestyle.

Behavioural observations
During the day, juveniles like to withdraw completely into a shelter. But if this catfish reaches the length of 20 centimetres it no longer needs a shelter where it can hide completely. Then a calm, but for the observer still visible spot at a corner in the rear area of the aquarium next to a large root or under a high solitary plant is sufficient for it. There it rests during the day most of the time. So its urge to move is significantly weaker than that of the more active C. macropterus. However those who believe that that a smaller tank will do because of the smaller length of adult A. torosus compared to C. macropterus will be taught soon enough of their error. Though the movements of C. macropterus are sometimes quite fast, A. torosus is lightening quick. Once under steam, movements are striking in so far as they are very fast-paced but still marked by lightness. When fed also during the day and no later than the onset of darkness, this catfish leaves its resting place immediately and actively looks for food. Then also younger specimens are no longer holed up in their hiding places and begin to roam widely through the tank. The species is not one that digs so that growing plants is possible with robust, bigger growing species.

A. torosus is a predatory catfish which likes devouring live food such as earthworms. But it will also eat frozen foods such as whole unbroken smelt and shrimp or mussel meat. After a short familiarization phase it does not disdain fish fillet itself. Juvenile catfish can be accustomed quickest to prepared food such as tablets or pellets, adult specimens however take it reluctantly. This species will gladly prey on smaller fish too. Their hunting behaviour is interesting, I could observe it well a large number of young, only a few centimetres large Archocentrus nigrofasciatus. Thereby it became clear how very quickly this predator catfish is able to lunge out. Although the young cichlids felt safe especially by roots and large stones. My nearly 35 centimetres in total length adult A. torosus registered them immediately, his barbels creeping slowly in their direction - a telltale sign. Apparently he was only waiting for switching off of the aquarium lighting. And indeed, even with room lightning on, he preyed on them. First, he scared the cichlids by restless searching movements, drawing them out into wild runs. Thereby he surprised them by a sudden, rapid lunge. Having had devoured seven cichlids the catfish went to his favourite place near a larger root and, apparently for the rest of the night, moved not from the spot.

This species can be kept with appropriately sized tankmates.

A skilled thief
A. torosus also likes to show his ability in a completely different kind of hunting; namely when it comes to snatching food from his predatory in-tank companions. He demonstrates this behaviour most readily when getting a raw deal during feeding and the other fish (because of the size of the food offered) need some time to devour it completely. Then the hunting instinct of the catfish awakes and he gets carried away with ever more daring actions: so he steals from adult Astronotus ocellatus a fish fillet, it only has to stick out just a little bit from their mouth. Persistently A. torosus first pursues the cichlids. In doing so his extraordinary agility benefits him: whichever direction the beleaguered cichlids take, he always manages to keep almost direct body contact and harass them further in turbulent movements as long as it takes from him to find a way for him to snatch or tear off the piece of food sought. If A. torosus has the opportunity to eat until properly full the need to find prey the very next day, even if the opportunity arose, is low. With him two or three days may pass in which he downright disdains further food. For adult specimens therefore a feeding twice a week is absolutely sufficient.

Territory
With conspecifics A. torosus behaves fairly territorially. Although you can still keep juveniles together if the aquarium provides enough hiding places, this is not so with adults and this does not work normally. They are too much the loner and their territories are too big, that is they usually include the entire tank. At best large public aquariums permit such a "coexistence". In regard to other fish species the territoriality is not so pronounced; an adult Aguarunichthys only defines its territory about 30 centimetres around its usual resting place. But this zone he then defends vigorously against all comers. Usually A. torosus in the context of its defensive action is able to to catch the intruders by fast and agile movements on exposed body areas like the tail fin with its mouth. It continues to pinch them in repeated attacks for so long as it takes for them to take flight. The tankmates will soon have learned its better to keep away from this territory and so, in sufficiently spacious tanks, socialisation for example with cichlids is certainly achievable. Even with larger cichlids the keeper does not have to worry about the well-being of his A. torosus because he is surprisingly assertive, especially at night. In that case he wanders around the entire bottom of the tank. The cichlids know that and then only remain in the middle and upper-water region. At this stage however, conflict with other bottom oriented fish may occur. If so, A. torosus tries to impress mainly through bumping or jockeying the other fishes. I did not observe injuries caused by this. So, usually, my specimen which is kept with several Pimelodus ornatus and Exallodontus aguanai gladly hands out some pretty rough behaviour. But the others have become used to his attacks and avoid or evade most of the time. If you want to keep A. torosus with other predatory catfish one should select on smaller, agile swimmers and provide them additional retreats. One should avoid keeping this species together with larger and similarly territorial Pimelodidae or Pseudopimelodidae, otherwise trouble is inevitable. In addition the keeper should always be aware of the fact that A. torosus is a predator catfish. For him too small fish - and these are basically all which have less than a third of his own body size - may not survive the night.

A true pet
Regarding behaviour towards the keeper there are clearly differences from C. macropterus which, even after many years, remains somewhat cautious. A. torosus by contrast soon discards such timidity after an initial somewhat withdrawn period. After some time even adult specimens lose their shyness and even take food from the hand. The high speed which they show thereby is unusual for predatory catfish. At the time of writing, from resting on the ground my specimen already after a short time sniffs/scents the smell traces starting out from the submerged fish pieces, then patrols a little on the ground restlessly and finally ascends in a searching movement. Especially through his two longest barbels in these moments literally vibrate and provide the best location information possible. He single-mindedly swims to the surface of the water where the food has been immersed. Seemingly while swimming by he then tears larger pieces off abruptly and, if necessary, with force out of my fingers which then at once disappear into the surprisingly wide-open mouth. Finally the catfish submerges, returns to his favourite place but for a moment and restarts to take the next chunk out of the hand.

Conclusion
“Just looks great” - this really sums up my impressions of A. torosus. This catfish impresses with the elegance of its body shape, markings and swimming movements. A confident powerhouse even in a predatory community tank. The experienced fan of predatory catfish will not be able to resist this species and should not be deterred by the relatively high price, if it can be found on the list of specialist catfish retailers.

This article was published in July 2010 in the German publication: Die Aquarien und Terrarienzeitschrift (DATZ) 63 (7): 26-29. My thanks apply here for the DATZ editorship and their editor-in-chief, Rainer Stawikowski, who gave me kind permission to publish this article on PlanetCatfish. © Copyright text and photos, DATZ, published here with permission.

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

Cat-eLog Data Sheet
Scientific Name	Aguarunichthys torosus  Stewart, 1986
Common Names	Bolt Catfish Jello Band Catfish, Stier-antennenwels (Germany), Yellow-band Catfish
Type Locality	Río Cenepa, Departo. Amazonas, Peru, about 4°28'S, 78°10'W, elevation about 210 meters.
Etymology	Aguarun=Peruvian Indian tribe that lives in Ecuador and "ichthys"=Greek for fish. This specific epithet refers to its muscular (torosus=muscular, bulging) build.
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Species Information
Size	346mm or 13.6" SL. Find near, nearer or same sized spp.
General Remarks	Smaller individuals can be a little fragile upon import, but will very quickly acclimatise.
Habitat Information
Distribution	South America: Cenepa River basin in Amazon River drainage. Amazon, Upper Amazon, Marañón, Cenepa (click on these areas to find other species found there) Log in to view data on a map.
IUCN Red List Category	Least Concern, range map and more is available on the IUCN species page. Last assessed 2020.
pH	5.8 - 7.2
Temperature	22.0-27.0°C or 71.6-80.6°F (Show species within this range)
Other Parameters	dH 5-15.
Husbandry Information
Breeding Reports	There is no breeding report.
Further Information
Reference	Copeia 1986 (no. 3), pp 663, Figs. 7-8.
Registered Keepers	There are 12 registered keepers, view all "my cats" data.
Wishlists	Love this species? Click the heart to add it to your wish list. There are 3 wishes to keep this species, see who wants what.
Spotters	Spotted this species somewhere? Click the binoculars! There are 6 records of this fish being seen, view them all.
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Last Update	2019 Sep 22 08:10 (species record created: 2011 May 02 05:56)

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