Chaca hamiltonii Gray,
1831 - Unneeded replacement name for Platystacus
Chaca lophioides Cuvier & Valenciennes,
1832 - Unneeded replacement name for Platystacus
Chaca buchanani Günther, 1864 - Unneeded
replacement name for Platystacus chaca
described using material (not deposited in an institution)
from ‘rivers and ponds of the northern parts
of Bengal’, the current accepted range is India,
Bangladesh, and possibly Nepal. There are reports
from Myanmar, Malay, and Indonesia but these probably
represent the other two species. According to Roberts
(1982) the name chaca is transliterated from
a Bengali name for the fish, and that this in turn
derives from the sound the fish makes when it is out
of water. This species reportedly reaches 19 cm SL,
but I have never seen true C. chaca that
Roberts rightly points out that the three species
listed above were not intended to be new species,
but were unneeded replacement names for Platystacus
chaca, which was the name originally used by
Hamilton. It was customary in practice that if a species
was placed in a genus with the same name i.e. chaca
into the genus Chaca, that the species name
would be altered to avoid tautonomy (‘the use
of the same word for the name of a genus and one of
its included species‘). This was unnecessary
(as per the International Code of Zoological Nomenclature)
and therefore the combination Chaca chaca
is valid and doesn’t need any replacement names.
described the colour and pattern as “above clouded
with green and black, and below with the latter colour:
but all its colours are dirty and ill defined. The
fins are spotted with black.”. See the original
drawing from Hamilton (1822). Some aquarists consider
that you can easily tell C. chaca from the
other species by the light tan colouration that we
tend to see in most specimens (but which doesn’t
match the colour given by Hamilton!), but also mainly
the pattern. This is because (as you can see from
the drawing from Hamilton) C. chaca usually
has some spots or blotches on the body (see images).
However, I recently came across a specimen of C.
bankanensis which also has pale colouration,
but also the spotting/blotching of C. chaca.
Therefore it is important that aquarists use the other
methods of identifying them discussed later, and not
just rely on colour or pattern.
specimens pictured by me were imported direct from
India. The bizarre specimen pictured by Anne Waal
(which I have only tentatively identified as chaca)
has numerous cirri on the head and body, some of them
being very thick. Even though these appear to be (currently)
technically the same species they differ greatly in:
colour, the extent of the cirri or papillae on the
head and body, and also the fact that Anne’s
specimen has much more conspicuous cirri around the
eye, than in my specimen and the one pictured by Ingo
Seidel. However, its colour and pattern does match
that given by Hamilton. The specimen was purchased
as a C. burmensis by Anne from an aquarium
shop, and at first glance its colouration appears
reminiscent of C. burmensis. However, based
on the great extent of the cirri on the head, and
the fewer cirri along the inside fringe of the lower
lip, I have tentatively identified it as a C.
Giebel, 1857 (emendation or mistake for C. bankanensis?)
I now had well
over 200 fry and more eggs to hatch out. Incredibly
the adults showed no inclination to cease spawning
but the eggs where smaller and I decided to separate
the sexes and move them into other tanks. I now had
more than enough fry to grow on and had to dedicate
two 18” x 12” x 12” and a 36”
x 12” x 12” for that purpose.
described this species based on one small (68 mm)
specimen from the island of Bangka (which he misspelled
Banka), in Indonesia, and this is where the species
its name (so it could have actually been called bangkanensis!).
See exclusive images of the holotype (RMNH 5405),
and the drawings from Bleeker (1862). The current
distribution for the species is Peninsular Malaysia,
the extreme southeastern tip of peninsular Thailand
(Udomritthiruj, pers. comm., and Vidthayanon, 2004),
Sarawak, Indonesia (Kalimantan, Sumatra, Bangka, Belitung,
and possibly Java - Tandjong), and possibly Singapore
(Bukit Merah). This species will reach at least 20
colour of this species can vary from reddish brown
specimens, which are usually the ones from Singapore,
Thai or peninsular Malaysia (see images by Ingo and
Kamphol) which I will call the Peninsular Form; or
some specimens from the remaining localities (which
I will call the Archipelagic Form) can be brown in
varying lighter or darker shades; some specimens having
greenish patches, and very few having blackish blotches
(similar to C. chaca).
It is possible that the peninsular Malaysian, Thai,
and Singapore specimens represent a
new species or sub species in their own right. I have
noticed that some Archipelagic Form specimens have
much broader heads when compared to others (and also
when compared to all Peninsular Form specimens), and
this is due to much longer maxillary bones. I thought
that this may be a clue to differences that may
warrant a different species or subspecies for the
Peninsular Form, as this is one of the differences
given by Brown & Ferraris (1988) to differentiate
their (then) new species. This was because I had seen
adult (19 cm SL) specimens from different imports,
of equal sizes of bankanensis of both forms,
which had much different sized head-shapes due to
the relative size of the maxillary bones.
I have since found this difference in small specimens
of equal size from the same import of the Archipelagic
Form (see images). However, none of the Peninsular
Form that I have seen have the broad head. My views
are then that these differences are not just related
to age / ontogeny / size, or in their own right differences
in species or sub species, but are probably differences
in the gender of the fish where the Archpelagic Form
is concerned. Again, however, it does not rule out
the possibility that the Peninsular Form is different
to the Archipelagic Form, especially when none of
the Peninsular ones I have seen have the broad heads,
as do some of the Archipelagic Form. As well as this
difference, and the difference in colour, the Peninsular
Form seems to have much smaller nasal barbels, than
the Archipelagic form.
In some specimens Peninsular Form (particularly from
Toh Daeng Peatswamp, Narathiwat Province, Thailand),
there doesn’t even appear to be a barbel, just
a small flap of skin. This of course needs more work
on it than I can give, but don’t be surprised
if we get a fourth species of Chaca, or a
new sub species described for the Peninsular Form.
As reported in
Ferraris (1991), some specimens have white eyes, (see
image). The white appears to be confined to upper
part of the cornea, and/or sclera, and not to the
iris, therefore I do not think that this makes them
blind. One of Kamphol’s photographs appears
to show an albino or a xanthic (yellow) specimen.
Young female?, exhibiting
green colouration on upper surface of body
Compare lateral line and
number of cirri to that of Chaca chaca
& Ferraris, 1988
species was described on the basis of four specimens
in the Natural History Museum, London (see image of
holotype). The largest type specimen is 20.35 cm,
and they originate from the Sittang River, Burma (Myanmar).
Obviously the species takes it’s name from Burma.
The shape, and
outward appearance of this species are more similar
to chaca than to bankanensis. It
tends to be a dark / black base colour, mottled with
light brown to tan colour, which can be the case for
some C. chaca.
I have found
that a small (approx. 7 cm TL) specimen from Pegu,
Myanmar, killed two Hypostomus and almost
killed two Bunocephalus species within a
week of being put in their tank (which was approx.
12 inch by 10 inch). The Hypostomus died
first, and at the same time the Bunocephalus
started to develop open sores/burns in their skin
and were hanging in upper water, but within a day
of removing the burmensis and doing a 25%
water change, they quite obviously started to pull
round and return to normal. I considered whether it
was the water parameters crashing, but the burmensis
was absolutely fine, so I consider that it was releasing
a poison into the water. Roberts (1982) states that
there is an axillary (pertaining to the axilla- literally
the ‘armpit’, so in fishes, near the junction
of the pectoral fin and the pectoral girdle, more
specifically the cleithrum - Diogo et al 2004) pore
in all Chaca’s but there was no evidence to
show that it secreted a poison. Based on my observations
I would guess that it does. He does state that earlier
authors had written that the “natives”
consider its flesh poisonous, although this report
probably relates to bankanensis. Ferraris
(1991) reports that certain feeder fish tend to die
if not eaten, and in the early 1990’s in the
Catfish Association of Great Britain magazine, I also
reported this in a tank of chaca and bankanensis
that I had.
Kamphol Udomritthiruj (who exported the burmensis
specimens pictured), has seen many specimens from
Pegu, Myanmar. He informed me that he has witnessed
burmensis curling the maxillary barbels to lure prey.
from Pegu, Myanmar
As mentioned earlier,
colour and/or pattern alone is not a reliable indicator.
Ferraris & Brown give some characters, but some
of them can only be accurately used by utilising dead
specimens and having knowledge of their anatomy (for
which Diogo et al 2004 is useful).
visually differentiated C. chaca from C.
bankanensis by the fact that C. chaca
has 5 soft pectoral fin rays, versus 4. This can quite
easily be seen if you look at the fish from above
(see images), even without counting the rays you can
see the different shape and relative size of the fin.
Unfortunately burmensis can also sometimes
have 4 rays, so the number of rays themselves are
not indicative. The first indicator to use then, is
to look for the tiny barbel on the rim of the posterior
nostril (see image). C. chaca and burmensis
do not have this, but unfortunately some Peninsular
Form bankanensis don’t either, so if
the fish has no posterior barbel, also then look at
the shape of the pectoral fin when viewed from above.
If it has a posterior nostril barbel, or the shape
of the fin is that in the image above, you have a
bankanensis. There are some other minor visual
differences that are sometimes quoted, but I find
it more reliable to use the ones I have given.
Chaca chaca showing
Archipelagic Form, showing pectoral fin |
showing pectoral fin
chaca from burmensis using the naked
eye is not as easy. Most of the differences listed
in Brown & Ferraris use information inaccessible
for aquarists using live fish. The number and extent
of cirri is very variable in chaca, so although
burmensis appear generally to have less,
some chaca do also. C. burmensis
tend to have a blacker base colour, but again this
can be seen in chaca also. Brown & Ferraris
state that “On the head, flattened flaps of
skin, usually branched at the tip, occur laterally
in the region of the cheek and opercle. None is found
along the dorsal surface of the head or immediately
posterior to the eye, as in C. chaca”.
However, in some C. chaca, there aren’t
any flattened flaps of skin on the head, or associated
with the eye either (although there are cirri, but
there are also some cirri in burmensis).
The easiest way I have found to differentiate them
using live specimens, is to look at the number and
relative size of the cirri along the inner edge of
the lower lip. In the C. burmensis I have
seen, they usually number around 10 or 11 small cirri,
and they don’t tend to have them near the corners
of the mouth. In the C. chaca that I have
seen, they tend to number at 14+ and tend to be relatively
longer and/or thicker.
Ingo Seidel, and Anne Waal for the kind permission
to use their images. Roy Blackburn for permission
to photograph his fish, and Mr & Mrs Pygott for
permission to photograph their fish. Martien van Oijen
of the Nationaal Natuurhistorisch Museum, Leiden for
the images of the holotype of Chaca bankanensis.
Mark Allen, for permission to use his image of the
Holotype of Chaca burmensis. To Dr Carl Ferraris
for his advice
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