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Well I've had this Rhamdia quelen for over a year now, it's grown to 22 cm and it's doing quite well in the tank it miraculously shares with a Crenicichla lepidota. Bothe species are endemic to my country, they dwell with no problems even in low temperatures (even 10C!)

And today, at the local fair, I came across these two little beauties in a group. To me, they're both Rhamdia, but why such difference in colour? They loooked like that in the tank, and they continue to look as different here at home. I can't post more than one pic at a time, so this one's from above:

Here's another angle. I'm sorry the picture's not good, I didn't want to stress them much. Far back, under a rock, a young Heptapterus mustelinus.

Marcos

I cannot tell much from these pics. You can always attach 3 pics to any post.

My Rhamdia quelen (if that's what it is) looks different from yours in the 1st pic. http://www.planetcatfish.com/forum/view ... t=+rhamdia

Thanks, Viktor. But it is the same species as yours, I'll show you another pic:

By no means I am an expert and especially not in Rhamdia. The fish in the first pic (unless it is stressed = very pale) looks like R. argentina. The ones in the dark pics - I can only say they appear to have the right silhouette of a Rhamdia. Have you taken a look at all the Rhamdias? There aren't that many at all in Cat-eLog.

I'd not worry about stressing them; besides, using lighting to take pics or at least a flash should not stress them much at all. My Rhamdia is a top survivor, the strongest, trickiest, and smartest fish of all ~100 kinds I have had.

I got 1 Rhamdia from Uruguay (I catched it myself) and 2 from Colombia. I expressly don't provide any species names, as I don't know them.

They do look quite differently, but they do share a similar attitude: they are all quite curious and active during the day, which is rare for catfish

Viktor, I'll try and take better pictures. Bas, have you got any pictures yourself?

Marcos

Well, I could get a pair of better pics. So my question is: can these two be the same species? Why such difference in colour -that has remained unchanged since I brought them home last Sunday, and under differente lightings?

And two more... thanks Viktor for persuading me to use the flash!

Unfotunately I don't have any pictures. I don't take that much pics

@ your fish, if the dark one was kept in the dark, I think they coulkd be the same species - the dark one most likely being a female.

My northern Rhamdia have quite different colors

En español, creo es possible son un especie. Quando el oscuro (no creo es la palabre correcta, sino no se mejor) vivia en el oscuro desde unas dias, es possible.

La oscura es una hembra, el claro es un macho

Mis Rhamdia del norte son muy differente en sus colores

The pics are decent. Now you really need an expert to weigh in. As I said, I cannot help you much. Their body and body parts proportions appear identical. I did try to count the rays in their fins. I am only sure that both have 8 rays in their dorsals, cannot be sure for other fins - I suggest you try. If they are all the same, it is a good chance it is the same species. But I agree, the color difference is striking for that to be true.

Bas, how can you tell the female from the male when they're so young?

Viktor, to count the rays in the other fins I'll have to wait a bit, since -being only recently brought home- many of their fins are rather torn, but it takes a short while to recover. It's an interesting means of stating if they belong to different species which I increasingly doubt. So far, no further color changes...

Thanks for answering my queries both of you

Marcos

Marcos Montes wrote:...It's an interesting means of stating if they belong to different species...

From my quite limited knowledge, different species within a genus usually have at least one fin with a different ray count (must be sure the fishes are of similar size/age) but far from always... and there exist variations, hence a range for a ray count is usually given... as I understand. Perhaps, there could also be sexual differences. I really wish an expert corrects me if I am leading you onto a wrong path.

Marcos

Basically, I was told so by 2 people I trust to know their catfish. I would be highly surprized if they were wrong

Of course Bas, what I meant to ask is if you can teach me what to pay attention to in order to tell a male from a female.

Marcos

This might help .

Jools

For Rhamdia I was told the male shows a lateral line, on a light background, the female has a darker body - unless stressed, then she looks like a male.

Obviously, this is not a method one can use for any Heptapteridae

Thank you Jools and Bas

Marcos

Hi Marcos, I had had to pump out my pond and, thus, had an opportunity to photograph my Rhamdia again:

http://www.planetcatfish.com/forum/view ... 13&t=30204

http://www.planetcatfish.com/forum/view ... =4&t=36786

... albeit it appears Jools thinks your fish are not Rhamdia but a Goeldiella eques. It looks like they have quite a characteristic color pattern. Do you agree with Jools?