Systomus hexazona: six-banded barb

[CK Yeo]

Picked up this thing from the LFS just now.
All I can say is WOW! Colours no lose to Harlequin rasbora and they are only 3hrs in the tank.

Look at the male! Colours are au natural! Asian fishes themed tank anyone?



ck

[trident]

CK,
Wow, very nice. color's solid.
I see, playing with your new lens..............

[hwchoy]

CK, Systomus pentazona (I prefer Systomus for this group for small southeast asian barbs) has a black spot under dorsal fin (at the posterior attachment). I would have called this S. hexazona if not for the partial bar (I have never seen any like that) and also the bar placement seem wrong.

I got a bad feeling some one has been hybridising them.

[CK Yeo]

The other side has 5 bands. Let me take a pic of its other side and see.
The rest of its friends look like they have normal 5 bands, so I would think this is banding variation?

I don't deny the possibility of hybridization but are they easy to spawn like tiger barbs in the first place?

ck

[hwchoy]

depends on how you count the bands. there should be only 5 prominent bands (1) across the eye, (2) between the eye and dorsal fin, (3) under the dorsal fin spine, (4) end of dorsal fin, (5) on the caudal peduncle, and (6) a very faint band right on the caudal base.

both S. pentazona and S. hexazona have similar bands except that S. pentazona have a black spot under the dorsal fin just before band (4). sometimes however this spot can get so small as to be invisible.

I notice empirically that shoal of hexazona tend to be fairly docile while pentazona are much more boisterous.

where did you get them and any info on their collection?

[hwchoy]

here's a movie of Systomus hexazona from Singapore. tonight I will post what a Systomus pentazona from Johor should look like.

* note the movie says Systomus johorensis, this is a error propagated by the Science Centre book which wrongly label the hexazona as johorensis.

http://www.hexazona.com/images/misce...azona%2001.mpg

[CK Yeo]

Collection location: Biotope Aquarium

ck

[benny]

Excellent picture! Looks like you have no trouble with the new gear.

Cheers,

[hwchoy]

Collection location: Biotope Aquarium

ck

I must go and grab

[CK Yeo]

Same fish, the other side. So confirm S. hexazona?



ck

[hwchoy]

yes, see the video. there seem to be two kinds of S. hexazona, one appear to be smaller and slimmer while the other like yours, is thicker bodied (like S. pentazona) and has some sparkle to the scales.

[CK Yeo]

er... Uncle Choy, your video not very clear. Show picture la!

ck

[hwchoy]

boh picture lah I waiting for you to contribute

you see the big fat Trigonostigma heteromorpha?

[CK Yeo]

??!! You purposely make me watch your video 3 times right? They look the same.

I thought you say you will show picture of real Systomus pentazona?

ck

[hwchoy]

what you mean they look the same? all of them are Systomus hexazona just like yours mah.

here you can watch the big fat Trigonostigma heteromorpha while I edit the pentazona pix. problem is I cannot recall who gave me the pix already so got problem with proper photo credit!

http://www.hexazona.com/images/misce...orpha%2001.mpg

[hwchoy]

OK, here are wild specimens of Systomus pentazona from Mersing. Note the black spot just under the dorsal posterior.

In particular I suggest you read the paper The Identity Of Barbus johorensis Duncker, 1904 (Teleostei: Cyprinidae) - Maurice Kottelat
Raffles Bulletin of Zoology 1992 40 (2): 187-192

in which Kottelat states that the two taxon may or may not be one species. I would add that I have personal observation of the dorsal spot being so variable as to be sometimes almost invisible in a population of "pentazona".

[CK Yeo]

I think the whole world is confused as well. When I do a google search, pictures of S. hexazona comes out.

Colour doesn't mean anything, does it? Both species are the same except for the slight banding differences?

ck

[hwchoy]

frankly we probably know quite a bit more than most outside the professional taxonomy circles, and even they got confused by the kiam hee (i.e. preserved) records which was why the confusion with P. johorensis. you really should go and get that Kottelat paper, explains a lot.

I have a separate suspicion that of the two S. hexazona "types", one is actually an "extension" of S. pentazona that has no dorsal spot, while the other one could be a separate species that looks VERY similar but I note their behavourial differences. Of course the second "type" could be just sub-adults of the nominal S. hexazona.

and you should know better to be very critical with pictures that you google off the net, especially for such esoteric species.

[CK Yeo]

Hahhaa. Orh. You have the pdf? I will be happy if the rest of the world does not call it tiger barb.

If uncommon species, I will be careful since the number of pictures that pop up will be limited and sometimes show totally different fishes. However, this one popped up 10+ pages showing the same fish...

It's a shame that SEA fishes with nice natural colours/shine get passed up in the LFS. They don't get much attention and has been sitting in their tanks for weeks.

ck

[johannes]

wow... S. hexazona... my favourite barb!