Rio Negro or Orinoco? (D. filamentosus)

[MacZ]

I'm unsure, are my Dicrossus filamentosus of the Rio Negro or the Orinoco variety? Anybody got an idea?
I took the pictures of the tank boss with all kinds of fin positions extended for display and relaxed. And I know the tint of the water might make it tough to decide or even impossible. In the end I'm just curious and don't want to tell anybody something wrong.

 

[rasmusW]

Have you checked tomC’s site? There is a fine diagram and description of the two varieties, as far as i can remember.

-r

 

[MacZ]

Yes, the illustration on his website is the reason I'm asking. I can't tell comparing them.

 

[Mazan]

It is really difficult to tell from this photo, but I get the impression that they are the Orinoco ones as it seems that the dotted or checkerboard pattern extends through most of the caudal fin. I can't see it that well to be sure though.

 

[MacZ]

I think I'll do it again tomorrow. Lights will be out in a few minutes.

The only thing I can say: The dots in the dorsal and caudal are mostly red and the triangular area in caudal is relatively slim.

 

[Mazan]

If the triangular (central?) area of the caudal fin is slim that would suggest the Rio Negro one, correct? In the photo of the fish in the foreground it looks more like that pattern reaches close to the edges of the caudal fin, but this is not very clear and could be because the fin is not fully opened. Some more photos would definitely help

 

[MacZ]

Some more photos would definitely help

Working on it. Trying to get some pictures during feeding later.

 

[Mike Wise]

If you have Schmettkamp's book "Die Zwergcichliden Südamerikas" he shows figures for both populations (s. 133). It is based on descriptions from Winkelmann (1976) TI #10: 12 (German) / (1977) ADI #16:12 (English). Winkelmann did not know which morph came from which system. We now know that Schmettkamp's Fig. 1 is an Orinoco form and Fig. 2 shows the Negro form. Winkelmann's IIIa = Orinoco, IIIb = Negro.

If you do not have any of these references, then you are much too young.

 

[MacZ]

I think I'll have to look in the university library for those. Or could you describe these illustrations?

If you do not have any of these references, then you are much too young.

Hearing that being 38... helps my self-confidence a lot, actually.

 

[Frank Hättich]

I think I'll have to look in the university library for those. Or could you describe these illustrations?


Hearing that being 38... helps my self-confidence a lot, actually.

Hope it helps young man

 

[MacZ]

Thanks, mate!

"Mancher Aquarianer hat sich an Crenicara filamentosa schon "die Zähne ausgebissen".
("Many a hobbyists have "bitten off more than they could chew" with [read: breeding] Crenicara filamentosa")

Nice one. But still not completely wrong.

Ok... now going by Schmettkamp my fish are of the Rio Negro variety and it might even be possible that one is a female after all.

Thanks so much Frank!