Catfish of the Month Right Arrow August 2004 • Article © Julian Dignall, uploaded August 01, 2004



Gulper Catfish, Ogre Catfish, Stormundet Rovmalle (Denmark) - Asterophysus batrachus   Kner, 1858

There are many big mouths in the catfish world. Thankfully most of them come with fins attached. Perhaps the biggest of them all is this month's featured catfish, Asterophysus batrachus - well deserving of the name Gulper Driftwood Catfish. The fishes enormous gape relative to its size and its thin, elastic skin allows this fish to simply swallow food whole in an instant. To demonstrate the point, the picture below is of an 24cm Asterophysus which has recently despatched a 40cm male Crenicichla marmorata; previously thought to be safe from the big gulp of the catfish.

Although uncommon in the wild, exports are available from time to time by they tend to come with an very high price tag as this is something of a collectable fish. Aside from the catfish connoisseur, this fish also appeals to those who just generally like the unusual or the "predatory fish set" that delight in the bold and lethal.

Asterophysus batrachusThese wonderful pictures come from Oliver Lucanus at www.belowwater.com, Oliver also reports some other aspects of this species both in nature and captivity.

The fish is uncommon in the wild where it is found in black water. Although described from Brazil it is also found in other countries' black water habitats. In nature, the fish spring into action the moment it gets dark; they cruise around the shallows at that time. While snorkelling I saw them eat angelfish sideways. Further testament to the utility of that mouth! Snorkelling at night with these fish can be extremely unsettling because the fish will try to swallow anything and will try to fit your hand into its mouth from every angle before giving up. The biggest animals I have seen in the wild were around 25cm, my animals are from 24-20cm and have not grown visibly in two years. They may eat fish at least double their own length.

The skin on the beast is very thin and flexible, which is why it can extend so grotesquely and swallow anything. Interestingly, threatened animals may blow themselves up with water like a puffer. They are however very easy to keep. I have never seen an infection on the skin, even with deep gouges from the fish trying to swallow each other. I have six fish together for four years, with no interaction, except attempts at swallowing each other especially at feeding time when there is a lot of food such as Krill or large earthworms in the water.

The moment there is anything new in the tank the Astrophysus will begin to swim around until they find it and try to swallow it. No matter if it is a net, arm or person or guppy. They know, (amazing in an almost electric fish sensory system sort of way), the moment that a new item has been introduced to the tank. Although they swallow anything in sight, these fish will filter feed when needed - just like a whale shark, daphnia are among my monsters favourites.

So, a certain candidate for the ultimate aquarium-suitable predatory fish; certainly one of the catfish worlds impressive predators.


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

Jump to next section Cat-eLog Data Sheet
Scientific NameAsterophysus batrachus  Kner, 1858
Common NamesGulper Catfish
Ogre Catfish, Stormundet Rovmalle (Denmark)
Type LocalityMarabitanos, Brazil.
PronunciationAss TERR oh fye suss - bat RACK uss
EtymologyAsterophysus: From the Greek aster, meaning star and physa, meaning bellows; in reference to the blind viliform processes around the periphery of the swimbladder characteristic of this genus. 
Jump to next section Species Information
Size 280mm or 11" SL. Find near, nearer or same sized spp.
IdentificationThe trapdoor like 'salmonesque' lower jaw is this species best external / visual characteristic.
SexingThe leading rays of the male's anal fin are fused to form a urinogenital organ used (at least in related genera) in internal fertilization of the female. This modification of the anal fin does not manifest itself until the male is approaching adulthood.
Jump to next section Habitat Information
DistributionSouth America: Orinoco and Rio Negro basins.
Amazon, Middle Amazon (Solimoes), Negro (click on these areas to find other species found there)
Orinoco (click on these areas to find other species found there)
Show it on a map (Click the map-icon to show/hide map of species distribution)
pH5.6 - 7.0
Temperature24.0-29.0°C or 75.2-84.2°F (Show species within this range)
Other ParametersA blackwater species.
Jump to next section Husbandry Information
FeedingThese fish will literally try and eat anything. Krill appears a real favourite, but all foods are accepted. The fish becomes more active during the day when not recently fed, feeding should be as with large pimelodids, less and less frequent with age. You would expect to feed an adult weekly. This may not be possible in tanks where the fish is kept with other species and so the fish should be fed smaller regular portions of food which may reduce its activity during the day.
FurnitureThe fish like to rest and hide in driftwood piles during the day but should be given at least 3 quarters of the aquarium as open swimming room for nocturnal prowling. Tall plants can also be used to coax the fish out during daylight feeding time in less stark surroundings. Choice of substrate is unimportant.
CompatibilityObviously care is required in housing fish with this species. Fish large enough not to be eaten but non-predatory to the point they will not eat the Asterophysus.
Suggested TankmatesFish large enough not to be eaten (amazingly for this species, this means at least twice the size of the Asterophysus, larger is less risky) but non-predatory to the point they will not eat the Asterophysus. Larger characins, doradids and loricariids are probably the best bet.
BreedingUnreported.
Jump to next section Further Information
ReferencesSitzungsber. Akad. Wiss. Wienv. 26 (s. 373) - pp403 [33] - Pl. 5 (figs. 13-15)
Registered Keepers(1) CFC (k: 2), (2) daniel60, (3) Lutt (k: 3), (4) soltarii007, (5) KenyanSandBoa (k: 2), (6) Koltsix (k: 2), who also notes: "Another one of my favorite fish. Easy to keep and easy to hand feed.", (7) ani-mal-lvr (k: 2), who also notes: "Just picked these guys up on 2-16-08", (8) SuperLaz, (9) RayGnz, (10) Gulper (k: 2), (11) ryguy713, (12) raymgnz215, (13) miles3, (14) arapaimag (k: 6), (15) Apostolis (p: 2, k: 4), (16) festaedan, (17) Nolapete.

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Breeding ReportsNone.
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Last Update2013 Jul 19 18:55 (species record created: 2004 Aug 01 11:22)

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