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he Ariidae family is wide spread, ranging throughout the continents of Asia, Africa, Australasia, South and Central America and there are about 80 species with the vast amount of them occurring along sea coastlines, estuaries and coastal lagoons hence one of the common name of this genus, ‘Sea Catfishes’. Until 2007 this species was known as Arius graeffei but there has been a name change for the members of the Ariidae family who reside from Southern New Guinea and Northern Australia, Arius to Neoarius.

 

 

Neoarius graeffei

 

The species we are concentrating on this month is one of only 5 represented in the freshwater rivers of Australia and Papua New Guinea, the 'Lesser Salmon Catfish', Neoarius graeffei.

Make sure that you don't let the p.H. drop too low as they like it more on the alkaline side. They have appeared periodically in the tanks of retailers and I would be interested if someone out there is still keeping this species.One cause for concern is the poisonous spines of the dorsal and pectoral fins as they will need to be treated with respect as it can take quite a while for a wound of this nature to heal up if you are unlucky enough to be punctured.

Colouration is not terrifiic in this species as they have a dark brown to blue upper body fading to a white/creamy underbelly. They are also treated as a food fish in its native habitats, they are renowned for their good taste if prepared properly but some fisherman treat them as pests as they can get caught in their nets and can take a considerable amount of time to disentangle them, and of course as well as avoiding the sharp spines they can ruin a net for future use.

One very interesting subject that was thrown up by my enquires was the  ‘homeing device’ or electrical fields that this species possesses and below I have reproduced a published paper from the Australian Defence Science site from Alan Theobald DSTO Defence and Darryl Whitehead of the University of Queensland Australia called, Using Fish Sense for Mine sensing.

“The superior sensory capabilities of fish may one day replace conventional sonar as a means of detecting marine threats such as sea mines. New research sponsored by DSTO's Maritime Operations Division at the University of Queensland's Zoology Department is exploring the electro-reception used by various fish species for possible military applications.

For example, catfish (Siluriformes) and sharks and rays (elasmobranches) can detect electrical fields as weak as 0.07 and 0.001 microvolts per centimetre, respectively. Researchers at the University of Queensland have shown that the Australian salmon-tailed catfish (Neoarius graeffei) has a sensitivity equal to or better than any other bony fish. In fact many indigenous animals, such as platypus and echidna, can detect the very low electric fields from their prey. 

The new research program will target species that inhabit estuarine waters and, indeed, migrate between fresh and salt water which have vastly different electrical conductivities. It is hoped that a good understanding of the physical and biological processes will result from observing differentpopulations of the same species.

 

Diagram of electroreception of its prey by a catfish (Neoarius graeffei)

“The illustration (above), for example, shows the changes in heart rate (top) and blood pressure (bottom) when a voltage of 70 nanovolts is introduced along the sides of the fish.” 

“This research has a long way to go before military applications can be realised. However, if it is possible to replicate the type of natural mechanism plus the signal processing chain, then an alternative to sonar could be produced. In the first instance, noting that the ranges at which fish themselves detect electric fields is of the order of metres, this work is targeted at the possibility of detecting mines, which might be buried in the sea bed and therefore difficult to detect using acoustics.”

“The basic electro-receptive unit in fishes is the ampullary organ (shown) which is the ampulla enlarged portion of the canal containing receptor cells and supportive cells. Receptor cells are electro-receptive sensory cells and the cup-like cells that encase them are the supportive cells.”

 

 

“The length and structure of the ampullary canals varies greatly between species and habitats. They can be six centimetres long on the marine catfish (Plotosus anguillaris), whilst on freshwater catfish they can be just 0.1 to 0.2 millimetres long. The ampullae themselves may contain hundreds of sensory cells and species may have thousands of ampullae over the skin.” 

“In nature only the toothed whales, such as dolphins and porpoises, have been shown to have evolved active sonar as a detection mechanism in water. Left : Darryl Whitehead, University of Queensland with Neoarius graeffei. Many fish species do, however, detect water-borne acoustic energy up to a few kilohertz from sources other than themselves.

“Typically marine animals have evolved other sensory systems such as olfactory, magnetic, electric and tactile, as well as optical. These systems are used for both detection of prey and navigation. By contrast, human technology has developed sonar systems, either passive or active, primarily to detect underwater objects. Since World War Two, vast military funding has been directed at the development of complex sonar systems. This research represents one step in the search for complementary approaches to sonar for underwater detection.”

Acknowledgments:  Darrryl Whitehead of the University of Queensland for his permission to use his paper, Using Fish Sense for Mine sensing.

 

Lesser Salmon Catfish, Blue Catfish, Salmon Catfish.

Arius australis, Neoarius australis, Arius curtisii, Arius greffei

Ariinae

Australia, from the Houtman Abrolhos Islands, Western Australia to Hunter River, New South Wales. Papua New Guinea, in the Purari River.

50.0cm (18ins) somewhat smaller in captivity.

20-27c (67-81f )

6.5-8.0.

Dorsal 1/7; Anal 15-19; Pectorals; 1/10 to 1/11; gill rakers on first arch 17 to 22; raker like processes on back of all gill arches, 12 to 20 on first, 15 to 23 on second, 15 to 21 on third; palatel teeth villiform, in transverse series of 4 oval patches, inner (vomerine) patches smaller than outer (palatine) patches, patches may fuse in larger specimens to form two patches or one large patch across palate; maxillary barbels moderately long, 2.5 to 5.8 in SL, extending to edge of opercle, usually to above pectoral fin base or midway along pectoral fin length or below dorsal fin spine in juveniles; head ovate, snout rounded or slightly truncate; head 3.0 to 3.8 in SL; eye oval, 3.7 to 8.4 (mean 6.1) in HL.

Dark brown, dark blue, fawn or ocher above, sometimes iridescent, fading to yellowish, cream or white ventrally; some fish from western Northern Territory with black and cream blotches; fins tan or bluish brown.

Only N. graeffei and Tachysurus berneyi out of the 5 species are deemed appropriate for housing in an aquarium as the rest get way too big for captivity. You would need a good sized tank of course as N. graeffei can grow to around 18" and if kept with other fish would need to be housed with larger Cichlids for instance, as they can be carnivorous, but as far as my enquiry's have thrown up they can be a good addition to a larger tank.

This fish and some others of its genus have an unusual breeding pattern for a catfish, it is a mouthbrooder!. The male incubates the eggs buccally for 2-4 weeks at at a temperature of 32c. When hatched the young are relatively large and at 2 months of age they are about 6cm long. The females ventral fins are modified into “claspers” to assist in the retaining of the eggs as they are extruded. The breeding season in the wild is reported to be the beginning of the wet season (spring or early summer).

In its native habitat they feed on insect larvae, aquatic plants, prawns, crayfish, molluscs and small fish. In the aquarium they will eat anything given such as earthworms, chopped liver, frozen brine shrimp, prawns, pellets, tablets and large flake.

Allen, R.Gerald. Freshwater Fishes of Australia.1989.
Baensch, H.A. and R. Riehl 1991 Aquarien atlas. Bd. 3. Melle: Mergus, Verlag für Natur- und Heimtierkunde, Germany. 1104 p.
Burgess, E.Warren Dr. Atlas of Freshwater & Marine Catfishes 1989.
Ferraris, C.J.Jr. 2007 Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types.

Photo Credits

Top image: © Johnny Jensen @ 
Middle diagram & Bottom picture: Australian Defence Science