Which species of Otocinclus is this?

Mike_Noren · Post by **Mike_Noren** » 25 Jul 2003, 21:46

As you can tell from the image name, my best guess is Otocinclus affinis?

The fish is about 3 cm (1.2")

Another aquarist stated that affinis is the only Otocinclus with unbroken dark sideband, like the specimen on the image has, so that that is a good character for the species - is that correct?

Post by **Silurus** » 25 Jul 2003, 23:09

There are about 13 species of Otocinclus with a color pattern like that. Kind of difficult to identify species within this group.

Mike_Noren · Post by **Mike_Noren** » 25 Jul 2003, 23:17

Silurus wrote:There are about 13 species of Otocinclus with a color pattern like that. Kind of difficult to identify species within this group.

What characters are used to identify the species? If they're external I can probably take a photo of them. If they're internal I can check them if one of the fish should happen to die.

Is there a key or something to the species of Otocinclus?

Post by **Silurus** » 25 Jul 2003, 23:24

Largely a mixture of external and internal characters. A number of them are osteological and difficult to observe even in dead fish. I might be able to get you a key from Schaefer 1997 [The neotropical cascudinhos: systematics and biogeography of the Otocinclus catfishes (Siluriformes: Loricariidae)], if you're really interested.

Sid Guppy · Post by **Sid Guppy** » 25 Jul 2003, 23:26

That's quite a pic from a fish that size!

maybe fizzle a bit with the software (I assume it's taken with a digicam) so Siluris or someone else might be able to count the rows and number of armourplates.
And another nice pic of it hanging on the glass, so the underside shows, plates, teeth etc. Those marks (number of armourplates and numbber and position of teeth) are among the marks for identifying Loricariids.

Mike_Noren · Post by **Mike_Noren** » 25 Jul 2003, 23:54

Silurus: Thanks, I'll have a look round, there is a decent chance we have that key already, now that I know where to look. I also have access to an x-ray machine so osteological characters are at least borderline possible for me.

SG_Eurystomus: Thanks! However, that oto is a fairly large target compared to some of my other shots, and as the oto was asleep I had all the time in the world to set up the gear and take the photo. I wish all my models were that accomodating! :)

Anyway, I'll try to get some usable pics of the underside and of the dorsal armor plates tomorrow - it'd be easier if the otos weren't so scared of the camera, though!

Graeme · Post by **Graeme** » 26 Jul 2003, 04:35

That's a Otocinclus arnoldi.

Graeme.

Post by **Silurus** » 26 Jul 2003, 10:09

Otocinclus arnoldi is a junior synonym of O. flexilis. What makes you say it's this species anyway?

YouTube · Post by **Jools** » 26 Jul 2003, 11:41

Graeme wrote:That's a Otocinclus arnoldi.

Or, as it is now known, O. flexilis which doesn't have an unbroken midlateral broad stripe that is shown on the fish above. I would say though if you are willing to take all sorts of close-up shots of this fish we might be able to have a stab at ID. As pointed out though, it is very tough without knowing where the fish came from and moreover, without taking it apart.

Jools

Mike_Noren · Post by **Mike_Noren** » 26 Jul 2003, 16:12

Anyway, I'll try to get some usable pics of the underside and of the dorsal armor plates tomorrow

I've taken some of those images now... I've only got images of the underside of the head yet, as the fish are scared of the camera, but I'm working on getting a closeup of the side of the head too.
The images are in very high resolution, so I'm giving an URL rather than pasting them into this post. If the picture fits on your screen you've probably got automatic image resize set in Internet Explorer (or a larger screen than mine).

http://mikes-machine.mine.nu/name_that_otocinclus.htm

On a personal note, I had no idea Otocinclus were spiky like that! The entire head is covered in spikes! And those teeth!
I don't know about you guys, but I'm impressed!

Graeme · Post by **Graeme** » 26 Jul 2003, 18:05

Lets just say i know from Keeping them Silurus! As for me they are O.arnoldi with no question of doubt. It's like the Botia Lohachata IS now called Botia Almorhae and do you see people calling them that?

Great Pictures Mike

Graeme.

Graeme · Post by **Graeme** » 26 Jul 2003, 18:08

Dont you mean O. nattereri as to the O Flexilis.

Graeme.

YouTube · Post by **Jools** » 26 Jul 2003, 18:26

Graeme wrote:Lets just say i know from Keeping them Silurus! As for me they are O.arnoldi with no question of doubt. It's like the Botia Lohachata IS now called Botia Almorhae and do you see people calling them that?

Graeme,

It's only through pig-headedness or ignorance that unarguably incorrect names persist in the hobby. That's something I spend great effort on trying to keep abreast of, and in many cases there is some contention, but <I>O. arnoldi</I> is about as much of a clear cut case as you can find. The example of <I>B. almorhae</I> is just irrelevant, people can call it what they want, but to _correctly_ ID it you would call it so. Besides, a quick check of http://www.loaches.com/ and I find they are using the new name...

What do you mean you "know from keeping them"? If you keep a fish does that mean you can ID it? I just don't get the point you're making here.

Jools

YouTube · Post by **Jools** » 26 Jul 2003, 18:27

Graeme wrote:Dont you mean O. nattereri as to the O Flexilis.

Who, me or Silurus?

Jools

Post by **Silurus** » 26 Jul 2003, 20:22

There's no such thing as O. nattereri.

Mike_Noren · Post by **Mike_Noren** » 26 Jul 2003, 23:49

I've now got a couple of fair profile shots of one of the otos. The otos are deathly afraid of the camera and go ballistic when it comes close, and as getting a good shot basically means getting camera and flash within 2 cm of the oto I'm probably not going to get better shots than these without restraining the otos.
Anyway, all the pics can be found at:

http://mikes-machine.mine.nu/name_that_otocinclus.htm

If there's some specific part of the oto you'd need a close-up of for identification, let me know and I'll see what I can do.

I was thinking - if we manage to reliably ID these otos, perhaps I should give the photos to FishBase and/or Planet Catfish for future reference?

YouTube · Post by **Jools** » 27 Jul 2003, 11:21

Mike,

Bear in mind those pics on fishbase are waiting ID verification. They are in the same boat as your pics, very hard to ID accurately these fish! That said, we should get down to having a close look at your pics as the detail is fantastic.

Jools

Graeme · Post by **Graeme** » 27 Jul 2003, 17:00

This is where people's opinion's Count! So any idea on this speices please.

I've give you mine.

Graeme.

Post by **Silurus** » 27 Jul 2003, 18:13

I have narrowed it down to either O. mariae or O. vittatus. You need to count the number of non canal-bearing lateral plates that separate the anterior and posterior fields of canal-bearing plates (5 or less=mariae; 6 or more=vittatus), as well as the number of canal-bearing plates in the posterior field (9 or more=mariae; 8 or less=vittatus) in order to distinguish the two.

Mike_Noren · Post by **Mike_Noren** » 28 Jul 2003, 11:40

Silurus wrote:I have narrowed it down to either O. mariae or O. vittatus. You need to count the number of non canal-bearing lateral plates that separate the anterior and posterior fields of canal-bearing plates (5 or less=mariae; 6 or more=vittatus), as well as the number of canal-bearing plates in the posterior field (9 or more=mariae; 8 or less=vittatus) in order to distinguish the two.

I also tried the key, and first got vestitus, but after re-keying came to vittatus/mariae. Which, as you say, are basically identical, and if one reads between the lines in Schaefer, it seems they may even be conspecific.

However, the pigmentation on the caudal fin, and especially the pigmentation anterior of the caudal fin, but below the lateral line, is similar (but stronger) in my fish and the vittatus in the key, but dissimilar to the mariae's two distinct W's. I'm also not sure I'd agree with the spines on the margin of the head being only "moderately" enlarged compared to the spines on the dorsal side of the head.

As you say a positive ID requires seeing the canal-bearing plates, and in these images they're obscured by the lateral pigment band. However, I *think* I can count 6 (or possibly 8) canal-bearing plates in the anterior part, and 5 in the posterior, which, again, suggests that it is a vittatus.

Hence I provisionally consider my fish to be Otocinclus vittatus!
(And probably a male!)

A heartfelt thanks for all the help!

YouTube · Post by **Jools** » 28 Jul 2003, 14:14

Mike,

Needless to say we get asked about Otocinclus ID quite a lot but rarely have an opportunity such as this to get such detailed images to look at. If you are able to and if you have the time I would certainly like to add some of your images to the site. Maybe even a few close-ups showing the characteristics used in ID that we can tart up with red arrows or circles or the like to demonstrate what we are looking at?

How does that sound?

Jools

Mike_Noren · Post by **Mike_Noren** » 28 Jul 2003, 14:52

Jools wrote:Mike,

Needless to say we get asked about Otocinclus ID quite a lot but rarely have an opportunity such as this to get such detailed images to look at. If you are able to and if you have the time I would certainly like to add some of your images to the site. Maybe even a few close-ups showing the characteristics used in ID that we can tart up with red arrows or circles or the like to demonstrate what we are looking at?

How does that sound?

Jools

I think it's a great idea.
I'll have a few more tries at getting an image where one can see the side line better, and I'll also take a detailed close-up of the caudal fin. I hope to be able to do that this evening.

Should I mail the images to you? Alternatively I'll just place all images on my website, and you can pick the ones you want.

YouTube · Post by **Jools** » 28 Jul 2003, 14:58

Mike,

I was going to put this in a PM, but it is probably useful info for others.

Sending me pictures in email is such much better for me becuase I use my inbox as my "to do list". I have a fast internet connection so sending lots of large images does not present a problem to me. It'll take me some time - maybe a week to two to get around to them as I try to work in a (roughly) first come first served basis but within the time available to me.

If I have 8 hours solid at the weekend and I pick off one of the big jobs (like the current reshuffle of the cat-elog), if I have an hour and a half at the end of a day then I'll post a couple of pictures. This is why some things take months to get around while other things take only a few days to do. Also this is why emailing me is better becuase I'm less likely to overlook it!

Thanks, this is going to be fun and very useful,

Jools

Which species of Otocinclus is this?

Which species of Otocinclus is this?

Oto photo session concluded. Sufficient for ID?