New group of 6 Microglanis iheringi... or are they?

[bekateen]

Today I obtained from my LFS a group of 6 adult or subadult Microglanis, the kind usually sold as Microglanis iheringi. Looking at colors, I see lots of individual variation. It's difficult for me to imagine that a little fish like this, spread out so widely across Venezuela and Colombia and even into Peru and Brazil, is "all one species." There are no similar described Microglanis from the immediate area, so my thoughts fall to undescribed cryptic species of similar coloration. I tried to get good pics of the pectoral spines today and overall wasn't very successful.

Here are 3 of the 6 fish. Each has a different color pattern on the tail. All of these patterns can be found on the CLOG page of C. iheringi, but of course, that would depend on those fish having been ID'd correctly to start with. And if there are cryptic species, then who knows what people have been sold in the past.

For two of the fish, I've typed characters which I think represent the color pattern, a 3 and a B with the hollows filled in. The 3 pattern was in the original description of M. iheringi. The other three fish which I received but I don't show here all have the "3" pattern on their tails.

Other variations in color pattern are:

• On the dark fishes, the brown/black color band on the caudal peduncle arcs forward and merges with the brown/black saddle below the adipose fin; but on the pale fishes, the two dark bands are clearly separate.
• On the two pale fishes, looking at the dark saddles under the dorsal fin, their anterior margin travels postero-ventrally, whereas in all my other fish, the anterior margine travels almost a direct vertical path.
• There are also dramatic differences in the coloration of the pectoral. pelvic and anal fins as well. The dark fish has bold flecked bands of color on the pectorals and anal, and some flecks on the pelvics, whereas the two pale fish shown here have either no color at all or very sparse, faint flecks in no organized line on these fins.
• The other thing which is odd is the dark base color on the smallest fish. I had read that the fish get darker with age, but my darkest fish are my smallest fish. Personally, I prefer the darker base color. Up close it reminds me of a fine horizontal wood grain.

Although there seems to be differences in caudal fin contour (more-or-less forked, with most-forked in the dark fish), one feature they all have in common is a smaller upper lobe of the caudal fin, with about 9‐10 rays in the upper lobe and 11 or more in the lower lobe.

Microglanis are certainly not "unspawned," but they aren't a commonly spawned fish, so I'm giving them a go.

Cheers, Eric

P.S., the photos are all magnified the same, so each fish is shown in proportionate scale. In all three photos, the field of view is 59 mm, from left to right.

[bekateen]

Here's my best attempt so far at their pectoral spine serrations. Clearly the pics are insufficient. Ugh.

Cheers, Eric

[Jools]

Hard work these guys! At least to ID. Do you have any info on their place of origin to add into the mix?

Cheers,

Jools

[bekateen]

Hi Jools, no not yet. My suspicion is these come out of either Colombia or Peru, but I can't rule out Brazil. I'll try to get info done the wholesaler. And, yes, I can tell this has been vexxing for a while: http://www.planetcatfish.com/forum/view ... 38&t=33984.

Cheers, Eric

[Shane]

So what the hobby has called M. iherengi for years is an incorrect id. This species is restricted to the Tuy and Valencia drainages of northern Venezuela. These are coastal drainages north of the Andes and it has been decades since any fish were exported from these areas. Several scientific names from these drainages have been incorrectly used in the hobby for a very long time because they were (correctly) applied in old aquarium books. When collecting shifted from Venezuela to Colombia, Brazil, and Peru hobbyists just continued using names like M. iherengi and Farlowella acus even though their fishes were from completely different areas.
I did once in Venezuela collect the actual M. iherengi in Venezuela but have no photos as my backpack was stolen while I was collecting in the creek. My car keys were in the backpack and so I ended up in a four hour stand off with the local villagers. Eventually my keys (but nothing else) were found and I was able to leave. However, during the stand off I had to let the fish go or they would have perished since I could not access anything in my car.
I think there is a good possibility that the coloration differences above could be related to sexual dimorphism.

-Shane

[bekateen]

Hi Shane,

Thanks for the background. Your point about the type locality of M. iheringi is not lost on me; that's why I said it's difficult to imagine the species would be so widespread.

The other species which suffers from the "it's the only name we know" syndrome is Microglanis cottoides, which has for decades been the go-to label for almost all unidentifiable Microglanis from Peru to Guyana to Amazonian Brazil and down to inland Argentina and Uruguay. But that species is a coastal Brazilian species, somewhat like M. iheringi is from coastal Venezuela.

In my opinion, more unsettling is not the mistaken use of M. iheringi by hobbyists, but the published papers by scientists who use Colombian specimens to clarify the description of M. iheringi. <facepalm emoticon>. Also, well known scientists have identified museum specimens from Colombia and Peru and Brazil as M. iheringi. It seems pretty clear we need more or new type material for the original M. iheringi and genetically testable samples for someone to properly characterize the inland populations from the coastal M. iheringi.

As for your last point on sexual dimorphism, that would be great if it proves true. There are very few notations in the more recently described species (and none in the old descriptions) of male-female differences, other than girth and genital papilla shape. I don't recall color pattern being one, but it's not unusual in other species so ... yeah I'd like to confirm that if true. Relevant to this point, both male female Microglanis collected from the rio Uruguay in Argentina have the dark wood-grained complexion.

I've got the original and revised descriptions of all Microglanis except M. ater. I haven't finished going through them all, but I'm working on them to extract diagnostic features and color pattern info for the clogs. Wish me luck; I don't expect it's a small task. It's what stirred my interest in this group in the first place and led me to get some after all these years of seeing them in my LFS's and passing them over.

Cheers, Eric

[Shane]

"In my opinion, more unsettling is not the mistaken use of M. iheringi by hobbyists, but the published papers by scientists who use Colombian specimens to clarify the description of M. iheringi. <facepalm emoticon>."

Yeah, I'll keep to myself the number of scientists I have seen grab an old TFH book to make an identification... Online resources have probably all but stopped this practice, but in the field, an old book may be all that is at hand.

I kept the same, or a similar, sp in a group of six for several years. They were in a ten gallon tank with several inches of leaf litter (oak and maple) and a sponge filter. My hope was that some eggs might make it in such a set up. I hit them with rain water every few months but never found any fry or eggs. If I were to try again I would try a false floor or maybe an uplift tube in a small cave to a specimen container.

-Shane

[bekateen]

I kept the same, or a similar, sp in a group of six for several years. They were in a ten gallon tank with several inches of leaf litter (oak and maple) and a sponge filter. My hope was that some eggs might make it in such a set up. I hit them with rain water every few months but never found any fry or eggs. If I were to try again I would try a false floor or maybe an uplift tube in a small cave to a specimen container.

Thanks again Shane. My plan is similar. I plan to decorate their tank with oak and magnolia leaves, pinned under piles of Manzanita twigs, with a few tight clusters of small (1") flat cobblestones, all on a thin (1/4" or less) layer of pool filter sand as a base. Hopefully eggs and fry will be protected in the crevices between the stones.

First, though, I want to get the adults in better condition. IMHO, they look healthy now, but certainly not "fat and sassy."

Also, trying to arrange a trip later this week to the importer of these specimens, to find more individuals of the different color patterns, on the off-chance that I have two or even three spp. in this group of six.

Cheers, Eric

[bekateen]

I went back to the source of my first six Microglanis and picked through the tank and selected 12 more. Some are big, over 50 mm SL! Some are dark and "wood-grained" (as I call the pattern) and some are bright yellow.

Also, the seller showed me the import sheet they came in from Colombia as Microglanis poecilus! Not Microglanis iheringi! Surprise?
One was very faded. Maybe same species??? Since there was only one pale fish, I saw no benefit to buying it, whether same species or not.

Also at least one I bought has a subcutaneous parasite. How do I treat this?

Thanks in advance,
Eric

[Jools]

It's likely everything in the catelog as M. iheringi is whatever you have and that the M. sp. 'venezuela' is M. i heringi. Just another one of those puzzles I had slated to have solved by the time I hit retirement.

Jools

[Shane]

My go to for parasite treatment of wild caught fishes has always been a formalin dip. However, I have no idea if it would impact a subcutaneous parasite. Maybe quarantine that animal separately and observe it.
-Shane

[Shane]

Jools,
I have two Venezuelan books with purported pictures of M. iherengi but have been hesitant to cite them as the books offer no specific collection location for the fish. That said, both photos show a darkly-colored pattern like the fish in the catelog as sp Venezuela.
-Shane

[bekateen]

My go to for parasite treatment of wild caught fishes has always been a formalin dip. However, I have no idea if it would impact a subcutaneous parasite. Maybe quarantine that animal separately and observe it.

They're in QT now.

I've seen something like this before in channel catfishes. If that case, the parasite used catfishes as one host in a two- host cycle: the catfish would have to be eaten by a bird or other predator for the parasite to complete its life cycle and reinfect other fishes. So if this is the same, leaving it alone won't harm the rest of the tank, but it won't help this fish.

Should I be concerned when medicating these fish that the bumblebees are smooth skinned fishes and not armored? Will they be more sensitive to meds?

Thanks, Eric

[Bas Pels]

I'd bevery cerefull with medicating catfish. All of them.

[bekateen]

I'd be very cerefull with medicating catfish. All of them.

With the possible exception of methylene blue (which I use rarely and only for fungusing eggs), I've found all the medications I mentioned above are very safe with all the corys and plecos I've ever kept. But until last week, I've never owned any Microglanis, or any other soft-skinned catfishes. So they are a total unknown to me in terms of how sensitive they are to medications.

If the parasite is the kind I described, requiring two hosts to complete its life cycle, I'm inclined to leave it alone and just pray it doesn't kill the individual infected fish. If it can't spread to other fish, the rest of my group is fine. But if it is a different parasite which might spread within the tank to other fish, then I'd like to treat the tank.

Ironically, I saw one other specimen at the LFS that had the same infection and I intentionally left that fish at the store. But on this fish I bought, I didn't notice the parasite until after I got home.

Cheers, Eric

[fishguy1978]

Love these mini cats. I have one in a 55g so I never get to see it.

[Shane]

I have used the formalin dip on, literally, thousands of wild caught fishes with no observed negative impact. Several people recommend dips as long as 30-60 minutes. I have found that even 5 minutes (with very sensitive fishes) is enough that you can watch external parasites drop from their host.
-Shane

[bekateen]

Thanks Shane.

Cheers, Eric

[bekateen]

Put together a video of all the fish on arrival.

Cheers, Eric

Microglanis poecilus? South American Bumblebee Catfish

[bekateen]

EDIT: After reviewing the photos of the fish shown below, I measured the dimensions of the container in which they were photographed. I underestimated its size, which was in fact nearly 4" internally. Therefore I've edited the SL sizes mentioned below to reflect accurate size measurements. The fish were in face nearly twice as long as I'd originally written. The current SL values are the correct SL values.

I think there is a good possibility that the coloration differences above could be related to sexual dimorphism.

-Shane

Hi Shane,

Following up on this, perhaps yes, but not what I was expecting. A few days ago I sorted my 18 specimens. Sadly, I found only 17, with one unaccounted for in the tank of 12. Maybe it's still in the tank; I don't know.

Of the 17, four are clearly of the dark wood-grained variety, with two showing obviously swollen abdomens so I suspect females (and the other two slender... so if males, then not sexual dimorphism unless we're proposing sneaker males). These fish are all about 40-47mm SL, with clearly bilobed tails, and they have a similar U-shaped brown saddle below the dorsal fin. [for reference, the container they are photographed in is 95mm across internally]

Next, seven share the yellow body color or nearly so. These fish are longer, about 45-60+mm SL I estimate; the longest is at least 65mm SL. These fish have caudal fins which vary from emarginate to gently bilobed; and the brown mark below the dorsal fin is more of a ventroposterior slanting trapezoid, more narrow on the base with the posterior edge nearly vertical, than a U-shaped saddle. They also all share conspicuous yellow "teardrops" lateral to each eye. Although two are slightly more girthy than the rest, overall all are slender (either all males, or some females immature included).

Finally, there were 6 which I could not sort easily. They are all small, about 45mm SL. Their caudal fin margins are bilobed, but to varying degrees, and their body colors are more-or-less dark yellow or wood-grained (one is yellow with bold brown spots - I imagine these spots more as blemishes on the yellow pattern rather than a unique color motif unto itself); finally, the brown area below the dorsal fin tends to be more the diagonal trapezoid than the U-shape. All of these are slender to slightly girthy; none are overtly rotund like the two small dark wood-grained fish.

Videos of all three groups are currently posted on Facebook. Later, I'll combine the videos and upload to YouTube for sharing here.

For now, I've sorted the seven yellow fish in one tank and combined the ten smaller fish in another. But if these are a single species, I would predict at this time that the males are long and yellow, and the females short and brown. I would not have expected the males to be so much larger than females.

This is so perplexing and intriguing to me. I need a student to help me run genetic tests on these to establish similarity and sexes. Or, the two extremes just need to breed without the other present. Ugh.

Cheers, Eric

P.S., side-note: All the fish, regardless of size or color or caudal fin shape, have a smaller upper caudal than lower, with about 7-8 soft rays above and 8-11 below (I'm vague here only because I don't know the convention for counting caudal fin rays ‐ at the upper and lower margins, when do you stop counting? Do you include or exclude the soft rays which terminate almost immediately? I think there are 7 dorsal principle rays and maybe 9 ventral principle rays).