name of 'Freshwater Shark" may give you a hint
that this months factsheet
(August 2010) is not for the
faint hearted and as we follow on from its cousin
which was covered extensively six years ago in Nov.
2004, this is really not a catfish for the home tank
as they can grow in excess of 6ft and are more of
a sport for big fish hunters and is an important food
fish in its native habitats. This of course does not
stop us at looking at this interesting species and
finding out how it 'ticks'.
There are at present
5 species of Wallago listed on Fishbase (2010),
our factsheet of the month W. attu, W.
hexanema, (which is probably W. attu)
Wallago leeri, now Wallagonia
leerii,W. maculatus, and a new species which was
described in 2004 by Heok Hee Ngfrom mainland
W. attu from the very similar W. leeri
you have to look at the dorsal fin first. W.
attu has a pointed extension while W. leerii
does not and is more rounded at the tip. The mouth
gape of W. attu ( see above) reaches beyond
the insertion of the eye and W. leerii has
the mouth only reaching to the beginning of the eye.
W. attu has a longer anal fin than W.
leerii with 77- 97 with the latter possessing
between 64-75 fin rays. You can see below the massive
mouth and the rows of conical teeth.
In the Mekong,
it is reported to migrate to smaller streams, canals
and to the floodplain during the flood season. When
the water level in the Mekong drops and the flood
recedes, it moves to the Mekong or larger tributaries,
where it stays in deep pools until the next inundation
period. Destructive to other more valuable food-fishes.
Bites strongly if handled, with its huge mouth, formidable
jaws, and band of conical teeth. W.attu is
threatened due to over harvesting. In Malaysia they
are bred commercially in fish farms for food.
It is ritually
offered to the goddess Kali by the Hindus (Talwar
and Jhingran 1991)
Pakistan to Viet Nam and Indonesia. Reported from
Afghanistan. Lower risk - near threatened status in
Western Ghats, India.
200.0cm (6ft 8ins)
Dorsal soft rays (total): 5
- 5; Anal soft rays: 77 - 97. Head broad, snout depressed.
Body elongate, strongly compressed. Mouth very deeply
cleft, its corner reaching far behind eyes. Teeth
in jaws set in wide bands; vomerine teeth in two small
patches. Barbels two pairs; maxillary barbels extending
to anterior margin posterior of anal fin, mandibulary
barbels to angle of mouth. Eyes small, with a free
orbital margin. Dorsal fin small, anal fin very long.
Mandibular barbel longer than pelvic fin; 24-30 gill
rakers on the first arch. Eye in front of vertical
through corner of mouth.
Body uniform silvery or olive
with golden gloss above, sides a dull white. A faint
orange/yellow band along the lateral line. Anal and
caudal fins dusky.
Care & Compatibility
Only juveniles can be kept
in aquaria and fed on tablet food, beef heart and
similar foods. This fish is not deemed suitable for
aquarium keeping due to its size, verocity and its
feeding needs for live fish.
they spawn during the premonsoon season from June
to August. As soon as
the streams are flooded by rains, the fishes run
up the shallow water for breeding,
build nests and offer parental care.
Juveniles feed mainly on insects;
adults feed on smaller fish, crustaceans, and mollusks.
Walago:Bleeker, in 1851 took the Indian fish
name 'Wallagoo', gave it generic rank, and used it
in connection with a new species.
of Flora and Fauna of Bangladesh. Vol.23. Freshwater
Fishes. Asiatic Society of Bangladesh. 300p.