D. filamentosus: distinguishing Orinoco and Rio Negro types

[DutchyIvo]

Dear users,

Tonight (at least here in the Netherlands) I was having an interesting chat with a friend about both our D. filamentosus., mainly focussing on what (possible) differences between the Orinoco and Rio Negro types are.

As far as we are concerned, both types are imported to Europa (and the US as well?).

One difference is described as follows
"There is a variation in the colour and pattern between the population occurring in the Rio Orinoco and that in the Rio Negro. On the male fish, the Rio Negro population has a narrow wedge of speckles in the fork of the caudal fin; this wedge is wider in males from the Rio Orinoco."
http://www.tropicalfishkeeping.com/profiles/lyretail-checkerboard-cichlid/

What strikes me is that in the picture of the supposed Rio Negro type, any red pigmentation in the dorsal fin seems substantially absent. Is this another distinguishing charateristic?

Unfortunately, I don't have any great picture of my, or my friends fish readily available. The best picture is probably this one:
http://i1358.photobucket.com/albums/q780/Mascha-Ivo/80cm takkenbiotoop/2013-07-14-07_zpsce149875.jpg

Some thoughts? More pics needed?

Thanks in advance!

Ivo, my girlfriend Mascha & our friend Mark

 

[Mike Wise]

Well, the 2 different forms have been known for a long time. It was originally reported by Winkelmann in 1975 (TI 9(32): 30), although at the time no one knew that they were geographically different. The easiest way to differentiate the 2 forms is by looking at the out edge of the male's caudal fin. The Rio Negro form shows a white/blue-white submarginal band while the Río Orinoco form does not (or only very thin and pale). The width of the spot rows is, like you wrote, also diagnostic. I don't consider the amount of red on the body diagnostic. It's a bit variable in populations of both forms. Looking at your fish, I'd say it's a Rio Negro form.

 

[DutchyIvo]

Dear Mike,

Thanks a lot!
Funny thing is, our dealer told is he tought they were Orinoco specimens and based this on the coloration in the fins of the female fishes they had in stock.

If we are correct, the fishes of our friend Mark are also Rio Negro type. Would you be so kind to verify?
I've attached a few pictures of his male fish. The first 2 pictures are a few months old. The third picture is a very recent one of his dominant male:
http://www.aquaforum.nl/gallery/upload/399977markvk_0_82_p5250361.jpg
http://www.aquaforum.nl/gallery/upload/525394markvk_0_82_p7050635.jpg
http://i1358.photobucket.com/albums/q780/Mascha-Ivo/DSC_5218_zpsc9b36f01.jpg

Thanks again!

 

[Mike Wise]

Your friend's D. filamentosus definitely are a Rio Negro form. As for your fish, I was basing it on the width and brightness of the submarinal caudal fin stripe. The photo is too dark to see the caudal pattern very well. Maybe better photos would help. The color of the females' fins are the same for both forms: clear for 'virgins', red for those that have spawned.

 

[DutchyIvo]

Hi Mike,

It took us some time to get some better photos (or, I should say: brighter ones, from an aesthetic point of view they aren't):
http://i1358.photobucket.com/albums/q780/Mascha-Ivo/DSC_5314_zps04ec73ad.jpg
http://i1358.photobucket.com/albums/q780/Mascha-Ivo/DSC_5335_zps0734b999.jpg
http://i1358.photobucket.com/albums/q780/Mascha-Ivo/DSC_5338_zpsaef6b803.jpg
Thanks again!

 

[Mike Wise]

For ID purposes esthetics aren't as important as being able to see the diagnostic features well. The pattern in the caudal looks like that of the Orinoco form: more extensive area of spots on the caudal and narrower submarginal stripe than that of the Rio Negro form. Love your P. annulatus, BTW.

 

[dw1305]

Hi all,
I can't help with your Dicrossus, but

Love your P. annulatus

They are a favourite of mine as well.

Is there a reason for leaving the dead leaves on the Pistia? they've got great roots.

Reminds me of Lukasz (Ruki) black water tank.

cheers Darrel

 

[DutchyIvo]

Thanks Mike!

Darrel, good observation on the Pistia leaves. That happend over a period 0f 3 days we weren't at home. I think it has to do with the shape of the closing lid of the tank.

 

[DutchyIvo]

Another short question. Recently I stumbled on some interesting statement, regarding the sexual dimorphism of D. filamentosus. A statement that I never read somewhere before.
At a German aquarium forum, someone stated males could also be identified by a red/orange speckle below the eyes, expanding and evolving into a stripe at later ages: http://www.aquariumforum.de/gallery/files/5/2/2/9/3/crenicara_bock.jpg

Any thoughts on this?

Also, for those interested, I added a picture of our tanks current state: http://i1358.photobucket.com/albums/q780/Mascha-Ivo/80cm takkenbiotoop/2013-12-11-01_zps37e9ae0a.jpg

 

[Mike Wise]

I've never read this, but it is possible. I've seen short red streaks on colorful females, too. I guess it depends on the age of the fish.

 

[DutchyIvo]

Here I am again

The pretty male below, Negro or Orinoco?
I'm leaning towards Orinoco, but I still find it very hard.

Also, I noticed our males have a lot of red coloration in their body, especially above the first two black blocks after the eyes.

Is that a location specific thingy, of is it perhaps food related?
(some of the frozen foods we serve them is Daphnia "intensive red" and Cyclops "intensive red").

Thanks again

 

[DutchyIvo]

Another picture: