Help identify this eel    /Neale  6/25/18
Hi WWM Crew! I’ve been searching through your Eel ID photos and posted questions trying to find an example that looks similar to the one I just obtained from my LFS. The closest match I could find was a Freshwater White Cheek Eel. Do you feel that is most likely? Note the yellow/ green stripe that outlines the entire Eel body besides the head of this 14 inch Eel with a healthy appetite for krill. I just am hoping to know as much as possible about the new inhabitant of my 110g and appreciate any thoughts you might have.
Thanks in Advance,
Brad
<Hello Brad. This looks to me like Gymnothorax tile, one of several euryhaline moray eels sold as 'freshwater morays' in the trade. While identifying can be hard, at least their care is easy to pin down. Without exception these are brackish to marine fish -- despite what some retailers and even wholesalers suggest -- and need to be kept in saline conditions. For a youngster, SG 1.005 at 25 C/77 F may well be fine, but as it matures expect to increase that, especially if it goes on an apparent hunger strike (which almost always happens eventually when these morays are kept in freshwater). Let me direct you to some reading, here:
http://www.wetwebmedia.com/fwsubwebindex/fwmorayart.htm
I've cc'ed Marco, our moray expert, in case I've misdiagnosed the species involved. Can I also remind you that a varied (no feeder fish!) diet has to be a priority with these, and indeed any carnivorous fish, and it's also important to remember these are not community fish and cannot be trusted with tankmates. Cheers, Neale.>

Help identify this eel   /Marco    6/26/18
Hi WWM Crew! I’ve been searching through your Eel ID photos and posted questions trying to find an example that looks similar to the one I just obtained from my LFS. The closest match I could find was a Freshwater White Cheek Eel. Do you feel that is most likely? Note the yellow/ green stripe that outlines the entire Eel body besides the head of this 14 inch Eel with a healthy appetite for krill. I just am hoping to know as much as possible about the new inhabitant of my 110g and appreciate any thoughts you might have. Thanks in Advance, Brad
<At first glance, I would have agreed that this is G. tile. I also once had a specimen with a faint greenish margin on top of the dorsal fin, but your eel looks different on the second picture. G. tile usually has white eyes, the picture shows orange eyes. Also, the body and head color remind me of Gymnothorax flavimarginatus, which has orange eyes and a brown to purple head. I've seen juveniles of them with the typical yellow to green outline of the fins (flavimarginatus=yellow margin). It vanishes with age and adults often don't have it anymore. Compare your eel to this one: http://www.saltcorner.com/AquariumLibrary/critterPics/G.%20flavimarginatus%20(BG).jpg Can you send better pictures? G. flavimarginatus can reach 1,2 m, they are really massive morays as adults and should be kept in a marine tank. Cheers, Marco.>

Re: Brackish moray ID      1/4/17
Hello Marco,
<Hi Ben.>
Allow me to continue our discussion,
I am thinking about other possible moray species that matches my eel, which are not Echidnas nor Gymnothorax.
In Fishforums.net a poster listed some species of morays that enters brackish & freshwater (I think this was quoted from WetWebMedia ;) One of the species mentioned, Uropterygius micropterus, is interesting, because when I see this picture here: http://www.tansuigyo.net/a/gao/x/551.html
<Not sure this is Uropterygius micropterus, but it's possible. Too bad the dorsal fin is not visible on the picture. Uropterygius micropterus has a light brown background color with a net of darker lines (see Fishbase).
Gymnothorax richardsonii has a more greenish color with a dendritic pattern. All Uropterygius spp. have a low dorsal fin limited to the area of the tail, while Gymnothorax spp. and Echidna spp. have a higher dorsal fin that starts behind and above the gill opening. The genera can easily be told apart with the eel in front of you by this character.>
Some of Mr. Eko's eels which he keep in his other brackish tank has the same patterns on the body with the Uropterygius Micropterus in the Chinese link above, though the coloration are different, that eel in the link
above are more dark brown, while Mr. Eko's eels are more grey-ish brown (except the one he gave me, it is green-ish brown).
<Compare to G. richardsonii, especially have a look where the dorsal fin starts.>
All of his small (<30 cm) eels he said were caught in brackish river, while the larger marine ones were from coral reefs around small islands. Price differences also reflect this, the colorful fully-marine morays costs a lot
more than the small brackish ones.
BTW, the small eel just ate a piece of thawed frozen shrimp. Interesting how fast it adapts with my aquarium, just a few days and it already ate frozen meal (smeared with garlic, thank you for your advice!), while my smallest E. rhodochilus still refuse anything else than live meal, even after living here for months!
Well, that concludes my observation today. Thank you for your kind attention & have a nice day!
<Have a nice day, too.>
Best Regards, Ben
<Cheers, Marco.>
Re: Brackish moray ID     1/11/18
Hello Marco,
<Hi Ben.>
Warm greetings from Indonesia. How's Germany today?
<Warmest winter I remember.>
I observed the eel and see no visible dorsal fin that starts above the gill opening. So there is a possibility that this is an Uropterygius eel instead of a G. richardsonii or E. rhodochilus?
<If you don't see said dorsal fin on the eel in question, but you are able to see it on your Echidnas, the mystery moray likely belongs to the genus Uropterygius (Anarchias would be another option).>
https://www.youtube.com/watch?v=plk4DmOhi4g
<Sorry Ben, I can't make out any detail in the vid, it's too dark and blurry. You should use some additional light source when taking pictures or videos.>
Thank you and Best Regards,
<Have a nice day.>
Ben Haryo
<Cheers, Marco.>
Re: Brackish moray ID      1/12/18
Hello Marco,
<Hi Ben.>
Nice to hear that your winter is warm, I hope this is good for your tropical fishes!
<I don't think they care. It's the same temperature in the house and their tanks all year round.>
Sorry for the bad quality of the film. I hope to borrow a better camera later, to take a better picture of my eel, or a cell phone with a strong flashlight.
<This would be good. Maybe we can get a proper ID instead of just guessing wildly.>
In any case, if my eel is actually an Uropterygius micropterus as I assumed, it is already 20cm maybe more, so I guess it's near adult (not baby eel anymore), as maximum length of this species is 30cm (according to Fishbase).
So, if it's really U. micropterus, then we confirm what Fishbase said is correct (that it is both brackish and marine). It also seems to be happy in its 1.008 sg aquarium, and are very docile in temperament, it is very
friendly with the E. rhodochilus and G. polyuranodon, no aggression observed.
<Good to hear.>
When I am back to Sumenep, I'll ask Mr. Eko in which part of the river he captured them: Was it at the river mouth, or further inland, did he used a submerged trap or did he picked them up in shallow waters. This way we could have some more info about the habitat of the eel.
<That's a good idea. Most of such useful information is lost with export, it's great you are close to the source.>
Too bad this species is not so common as pets, as I think this eel could be one of the easier ones to keep. It is not as pretty as E. rhodochilus, G. polyuranodon or G. tile, but it is not so hard to feed and not so shy, mine seems to spend almost as much time swimming outside the pipes as waiting inside. It also does not run away from my hands when I am cleaning the aquarium, interesting eh?
<Yes, especially since Uropterygius species in general are reported to spend most of their lives hidden in rocks and mud, but to be honest: not much is known about the behavior of members of this genus at all.>
Well, thank you and have a nice day!
<You, too!>
Best Regards, Ben
<Cheers, Marco.>

Re: Brackish moray ID      1/17/18
Good evening Marco,
<Good morning Ben.>
Greetings from Indonesia!
I am aware that there are not much information about fresh and brackish water morays, so indeed, as an eel-enthusiast who lives close to the source, I'll share whatever information that I can gather from around here.
<Kudos to you.>
As for our mystery eel, I visited Mr. Eko this afternoon, and asked him a few questions about the eel. His answers are as follows:
1. The mystery eels that he has, were captured in the river in Java, a bit farther from the river mouth (estuarium), but he said this species are also known to inhabit not only on the river, but also the area around the river mouth and the beach. So, they can be found in both full saltwater and light brackish. They are from shallow waters, usually found in sandy beaches hiding in broken corals or under clamshells, or in the soft mud of the rivers.
2. They are known to hunt crabs and shrimps on the shallow waters of the beach and rivers. They can burrow their bodies in both soft sand and mud, but they are more active in swimming around, than other types of morays which spent much of their time burrowing or hiding. They could hunt during the day or during the night as they please.
3. These eels were usually not captured by fishing hook, but by submerged traps.
4. They are not territorial, plenty of them can be found together in a small area, often bunched together under a clamshell or a rock, like noodles.
So I thanked Mr. Eko for his info, and he promised to inform me if there are any other strange eels he captured or obtained. Before I left, he offered me to buy a pike conger baby at discount, as apparently he has one left. He told me that the pike conger were captured in the same area where they captured the mystery eel. But I declined (pike congers are known to be aggressive and has sharp teeth), and instead I bought another mystery eel from him.
So now I have two of these "mystery eels", I hope they will be happy in my aquarium. Mr. Eko took pictures of the conger and the second mystery eel, I attached it here. His shop is not as dark as my kitchen, so maybe these pictures are better for ID ing the mystery eel?
<Yes, much better. Can't see details of the head, but at least the body coloration is visible. It's definitely no G. richardsonii, G. tile, E. rhodochilus, G. polyuranodon. The coloration of the body matches Uropterygius micropterus quite well, so this ID is probably right. The ecology you describe above also concurs with what is known about this
species. Only that it seems to live so openly is something I had not expected from a Uropterygius species. I think this eel can be added to the list of moray species in captive care.>
That concludes my e-mail for now, I will share to you more from my research when I get new information.
<Thanks Ben.>
Warm Regards, Ben
<Cheers, Marco.>

a bunch of morays in a bucket      12/28/17
Hello Neale, hello Marco, hello all,
<Hi Ben.>
Warm greetings from Indonesia to all you amazing people at WetWebMedia.
So, I visited an ornamental fish procurer, the one who actually captured the fishes. I asked for fresh or brackish water morays. He showed me a bucket full of eels that he captured several days ago from a river in the
north of Jakarta, not far from the estuarium river mouth.
Here are the pictures of the eels.
So, which one is Gymnothorax Tile? I can recognize one tiny Echidna Nebulosa, but the rest of them I have no clue. I am not even sure that they are all morays. The guy who captured them all made no distinctions, all of those eels are "Belut Muara" to him (Belut Muara = eels being caught in brackish water).
<The pictures show too little detail for a proper ID. Would need to clearly see the heads of most of the eels. As you already know there is E. nebulosa and probably G. richardsonii. There might also be one (the grey eel with tiny spots) or two Gymnothorax pictus, which are easily IDd by the dark spots in their eyes. However, I cannot see the eyes on the pictures.
Gymnothorax tile are grey to brown with yellow the golden speckles. The older the eel, the less golden speckles. See here for some pictures: http://www.wetwebmedia.com/fwsubwebindex/fwmorayart.htm 
Young G. tile look like this:
https://www.aqualog.de/wp-content/uploads/2017/05/Gymnothorax_tile-baby.jpg 
The pictures you mailed of Mr. Septian's eels also show some G. tile and one potential G. pictus. >
Thank you & have a wonderful day!
Best Regards, Ben Haryo
<Hope this helps. Marco.>

Brackish moray ID (file size fixed)   12/30/17
Hello Bob, Neale, Marco, and all my WetWebMedia friends, a good Friday for all of you!
<Hi Ben.>
(Dear Bob, sorry for the large files, my bad. I have re-sized the file and re-send the message. I hope this time it's in the correct size. Sorry for the inconvenience).
<<Accepted. B>>
Marco, thank you for your kind explanation. Brackish water is fascinating, isn't it? I like the concept of brackish and near-freshwater estuarium as nursery ground for various juvenile marine moray species, so they could get the nutrients from freshwater and cover to hide from marine predators. Our estuarine waters are indeed dark and muddy in many places, unlike the clear bright waters of the coral reefs just a few kilometers at the open shore.
I have made plans in the future to visit some of those estuaries & rivers in North Java and in Yogyakarta & record their salinity levels & record the tales about morays from local fish catchers.
<Nice. If possible compare the salinity at the bottom of the estuary with the surface. Can be quite different.>
I will keep you informed.
<Very good.>
I am also interested in marine aquarium, but maybe later when I have more space. Space is a problem for me as I cannot find place in my house for another aquarium. I often found myself donating my pet fishes to other friends, not long ago I donated my Anguilla bicolor to a friend who has a larger aquarium, as it has grown almost to 1 meter in length & looking very stressed & cramped in mine. It had spent almost 3 years in my aquarium.
Currently I am also looking for a new home for my Monopterus albus, it has grown to 70 centimeter and has shown signs of stress, before it's very active, now it became lethargic, often perched itself on top of the filter (glad my aquarium is covered!) or bury its head on the sand (glad the bottom of my aquarium is sandy, not gravels!). I have
donated other fishes in the past as well.
<You seem to like all eels, not only morays. As far as I know, M. albus does travel into brackish waters, but prefers freshwater in the long care (and aquarium care).>
Well, today I went to my hangout at Sumenep, where fish lovers hang around.
I visit my friend Mr. Eko, a specialist of brackish water fishes. Not only catching fishes in our estuarium and rivers near the sea, he also quarantine them and acclimatize them then supply them to ornamental fish seller. He has cement pools for this purpose, as well as various brackish, fresh and marine aquariums. He is an aquascaper too. He showed me his lovely Echidna nebulosa, which is very fat and is an adult (about 50 centimeters). He proudly told me that he kept this eel for almost 2 years in this brackish water, and describe how the Echidna survived a jump out of the aquarium for 2 hours! It's the best eel for aquascaping marine tank, he said, because of durability, docility and beautiful skin patterns. His tank is about the same size with mine, but mine is a bit longer. I sampled and tested the water on the E. nebulosa tank with my hydrometer, it's 1.012-1.014 after 3 tests. He told me that it was originally the water from the river where the Echidna came from, but he does regular water changes to acclimatize the eel. His aquarium does not look so appealing, with no sandy bottom and only a handful of dead corals for the hideout of the Echidna.
But the Echidna does looks healthy. I wonder how that's possible, as to my knowledge, E. nebulosa cannot survive anything below 1.018, so is this an anomaly?
<Surviving and thriving are two different things. E. nebulosa are very hardy and it's not the first time I hear it was caught in brackish waters.
1.014 is already mid brackish to high brackish. It's well possible the eel will survive this for months or a few years, but nothing I can endorse for permanent care based on the biology of this species.>
Knowing my love for eels, he showed me a low-water aquarium full of small eels, he said they're totally brackish. I sampled the water and it's 1.008 - 1.010 after 3 tests, so rather similar to my aquarium. I asked about the Latin name of the small eels and he said he has no clue (kind of expected).
So he gave me one, and asked me to study the eel and tell him what species it is according to science, and I can give it back to him later. It's very very small, maybe only 15 centimeter, and when I put it on my tank, it looks comfortable and it snuggled itself under my largest Echidna rhodochilus. They looks compatible in the pipe, they're almost the same in color and I noticed it also has white blotches on the mouth. Is that a juvenile E. rhodochilus?
<Probably. Can't be sure. The pictures are rather blurry and dark.>
I look at Fishbase and noticed that Echidna leucotaenia also has white blotches on mouth. What do you think it is, dear Marco?
<Based on what I see: E. rhodochilus. Echidna leucotaenia has more and different white spots.>
Well, thank you for your time & have a nice weekend!
<No problem. Have a nice weekend, too.>
Best Regards, Ben
<Cheers, Marco.>