Betta Foerschi, Mandor et Strohi

What would you like to know?

Hello,

I keep the fish:

Betta foerschi with fishing place "Pangkalanbun"
Betta mandor with fishing place "Mandor"
Betta strohi with fishing place "Nataisedawak"

My first question will be:

How can you visually tell the difference between these three fish ?

The answer will vary, depending on who you'd ask. I strongly suspect they are all populations of the taxon foerschi. However that doesn't asnwer your question as you asked it.

I believe, and someone please correct me if I'm wrong, that strohi has a spaded caudal fin, the spade being in the upper third part of the fin in lateral aspect. I'll get the descriptions out tomorrow and take a closer look for you.

Don't pay attention to their colouration and gill bar colours; they're not diagnostic, similar and all variable depending on mood.

From the original descriptions and published notes by ichthyologists:

mandor:

Diagnosis. Betta mandor is unique in the Betta foerschi group in having the following combination of characters: twin red bars on opercle when; male with black body and female with brown body when live; 32-34 lateral scales; 25-28 anal fin rays; 6.5-8 subdorsal scales; slimmest body (body depth at dorsal fin origin 21.2-24.2 % SL); and interorbital distance 27.1-32.1 % HL.

Remarks. (Excerpt) Longer caudal fin than Betta foerschi; smaller caudal peduncle depth than B. foerschi and B. strohi; larger caudal peduncle depth than B. rubra; smaller snout length than B. foerschi.

stohi:

Discussion. (Excerpt, translated from German) Photo observations taken by Stroh and Linke show very different fright colour patterns: Betta foerschi has conspicious dark and light longitudinal [flank] bars, whereas B. strohi has one faint, narrow longitudinal [flank] bar with a couple of converse bars [vertically intersecting with the [horizontal] longitudinal bar]. Betta foerschi was collected from Palangan (Sampit river system), B. strohi from Sukamara (Jelai river system), 200 km southwest of the B. foerschi type locality. The Sampit and Jelai basins are seperated by two hill ridges and two river systems.

Thank you for these informations.

I knew this theoretical description but it is not easy to observe when the fish is alive. We can see when the fish died.
I hold the fish long ago and I often had babies. I confirm, the color of red bars on the opercula are not valid.
The observed visual differences are the shape of the mouth, head shape and form of the caudal fin.
They exist in many photos but there is much mixing.
Do you have any reference images showing these fish by Ichthyologists?
Is there a way to control the fish by an expert who can certify the origin or affiliation?
Specialist in Germany, do you have references of these fish décritent by Stroh and Linke? Maybe with pictures?

Excuse me for bad english !

Dale,

You've hit the nail on the head; that's the problem when, generally speaking and in my opinion, populations of a species taxon are raised to species level (e.g. strohi, mandor). Usually the only way to be sure is know exactly where the fish were collected, which usually cannot be told from their appearance.

I'm afraid mouth shapes are not diagnostically relevant in Betta, to the best of my knowledge, head shape in lateral aspect can easily be explained away by phenotypic plasticity and has therefor not been used as a diagnostic anymore since the 90s for the genus. Caudal fin shape isn't diagnostic for this species group (foerschi) either, I'm afraid. Earlier I mentioned the spaded caudal in strohi but am now unsure where that came from; I did not find it in any of the descriptions that I have read again today. The opercle bars are indeed, as we both mentioned not diagnostic in live (they might be in a preserved [vast] state). I've seen about all members of the group, and even more populations of foerschi, in which the colour changes depending on mood and lighting (supported by my foerschi from Tangkiling photographs).

I have the original descriptions with their photos (some of poor quality and in black and white) but cannot upload them; that is illegal. It doesn't matter; the state of the photos are not revealing anyway. I would be interested in seeing Stroh's photographic material also, if anyone has got it? I'm pretty sure Linke's photos can be found in his book(s).

Basically it comes down that there is, as far as I'm aware of, no clear-cut answer on how to differentiate foerschi, strohi and mandor superficially and in live condition - other than the fright colour pattern quoted in my previous post.

Stephan,

For information,

Today, in trade, we find these fishes. The way to differentiate them is the following :

Betta Strohi : Double bare opercle gold for the male and female.
Betta Foerschi : Double bare opercle red for the male and gold for the female.
Betta Mandor : Double bare opercle red for the male and gold for the female, dark green reflects on the male flanks, shorter than the snout foerschi.

With this description, it is difficult to be sure to have good fish !
If you have more information on these species with fotos or if you know an Ichthyologist, I can give you my e-mail exchange. It would be very nice.

Sometimes we have fishes by the supplier ... but how can we do be sure ??
For fishes that I own, do you know them ? Do you know the following places fishing ?

Betta foerschi with fishing place "Pangkalanbun"
Betta mandor with fishing place "Mandor"
Betta stroh with fishing place "Nataisedawak"

Is there a list of different type of Betta Stroh, and Mandor Foerschi that have already been detained ?
With their places fishing ?

Stephan,

The way to differentiate them is the following :

Betta Strohi : Double bare opercle gold for the male and female.
Betta Foerschi : Double bare opercle red for the male and gold for the female.
Betta Mandor : Double bare opercle red for the male and gold for the female, dark green reflects on the male flanks, shorter than the snout foerschi.

No it's not. The colour of opercle bars is mood dependant.

Betta foerschi with fishing place "Pangkalanbun"
Betta mandor with fishing place "Mandor"
Betta stroh with fishing place "Nataisedawak"

Yes I know all three with their collecting sites; species IDs are correct.