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FAQs about the "Green Wolf Eel" , (Congrogadus subducens), Family Pseudochromidae, subfamily Congrogadinae...

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Here's a beauty at Morgan Lidster's Inland Aquatics in IA.

Peacock wolf eel in distress     7/27/18
Hello fish friends!
<Hello Shelly>
I currently have an 18 mo old, female, captive bred, Peacock Wolf Eel who has abruptly taken a turn for the worse. We are her third facility, and I have had her about 5 weeks. She is currently housed in a large round holding tank, alone, and her condition is something I have never seen. I browsed the internet and the only thing close to her condition is something similar to a case I read about on your forum.
She was in great condition when she arrived, very active (for a wolf eel) and a normal appetite. She ate for me the second day after her introduction to her quarantine tank. About 8 days or so after she arrived,
I found her laying on her side. To be honest, I thought she was deceased and when I went to net her, she went upright and somewhat swam away from the net. Since then she has had an ultrasound and x-rays with no abnormalities or alarming findings. She is now refusing food and has serious swimming/mobility issues.
<Not good>
She seems somewhat interested in food when it enters the tank and once has taken it in but immediately spit it out.
<This is not uncommon on certain fishes when internal parasites are present. Another cause may be thyroid hyperplasia (caused by iodine deficiency.)
When she tries to swim it is more like a hopping motion. She has use of her pectoral fins and is very alert and aware but to me it seems like she is suffering from some sort of paralysis from the rib cage and lower.
She does react when you touch/pinch her lower tail area, but she doesn't seem to be able to move it on her own. I read about the green wolf eel that had a goiter and paralysis issue that was aided by iodine supplements
<This is true and probably the case here>
and I'm now more hopeful then I was. I’m wondering (and maybe hoping because I am at a loss) that this may be due to some vitamin or iodine deficiency?
<or maybe both>
Like everyone, I do not want to lose this animal over an issue that can easily be fixed so I am reaching out in all directions for any advice or suggestions you may have for me.
<I hope it´s not too late, unfortunately the symptoms of these deficiencies are only visible when the problem has been present for weeks or months, because your eel is not taking/swallowing food. The only route here is to add them directly to the tank water. Eels can go through fasting periods for weeks with no problem, so don´t be concern for her not taking food for a while as long as it´s not emaciated. hope this helps and please keep me posted.>
Thank you for your time and your thoughts.
Shelly Pettit
<Welcome. Wilberth.>

Green Wolf Eel (Congrogadus subducens)     5/5/17
Hello Crew!
<Li'l Jen>
I just wrote in last week regarding an unknown hitchhiker and as always received quick and prompt replies. Thank you again and in advance!
We've had our Green Wolf Eel for over a year now. She's been the model of health and as hardy as promised. However, maybe slightly less than a month ago she began to turn down food. She would eat but seemed to go slower when swallowing as opposed to just inhaling pieces in one big gulp.
<I see... in your pix>
I had read a while back on here an old FAQ regarding the same animal turning down food. I had remembered reading you'd seen them go off foods for months and advised the person to add vitamins and keep trying. I've
done just that and since this started she'd take a piece here or there. No where near the amount of silversides she normally ate.
I know behavior is a tell tale sign with fish as well as water conditions and other signs in tankmates. However, we've been doing our regular maintenance, conditions have all been at the ideal range and tank mates are all normal as usual. Even she was. I noticed even a week and then two weeks after starting to turn down food, she still stuck to her daily schedule.
During the day her and her Snowflake Eel BFF would leave their cave, move to the other side of the tank, hang out for a while, then move back when it was dinner time and stayed through the night. I decided to continue taking
the advice and just waiting things out. While the food was a sign of something, she still seemed exactly the same.
However, as of two days ago she slowly started laying oddly, moving in quick motions as if it was uncomfortable to love, and shortly after began laying on her side as a fish does when something is wrong. She had slightly
labored breathing.
<Likely related to the tumor here>
Our Snowflake Eel has become very big and no one told him. So he tends to shove himself at any cost into the tiny spaces our Green Wolf will lay.
Ever since she's been laying on her side he hasn't alternated his sleeping spots, as he usually goes from "cave" to "cave." He's made them all over the tank. He hasn't left her side since then. I thought it was possible because he was shoving himself in with her, that she had no choice but to lay on her side.
This morning when I finally took a look at the tank, she was still on her side with occasionally lifting up her head. She'd lift it like she was going to move the way she normally does, just switches positions, but never moved an inch. Not since this morning.
This evening I noticed a large bulge. Very large. I had read another post on here about a Green Wolf Eel with a bulge in a similar spot but the picture shows the Wolf Eel upright and color looked good. You alluded to a goiter condition. What exactly is that?
<An endocrine tissue growth related to deficiency in iodide-ate>
Is it something that just happens so suddenly? Is it fatal?
<Is very likely either a goiter or other tumor>
I know you can do a diagnosis on a picture so I won't ask for one. If you see the picture and read the description and get an idea on anything I can try, that's all that matters to me. I just want to know what I can try to do without being positive on what's going on. She seems miserable. She has been so hardy this whole time.
I do know vitamin deficiencies can cause problems like this.
<Yes; particularly B's>
I have a difficult time getting both "Eels" to take vitamin soaked silver sides. They are so picky down to what part of the fish they get and even how I position it on the tongs to hand it to them. He gets vitamins, but I took it as all food should be soaked and that's not the case with them.
Would that still happen this suddenly if a vitamin deficiency?
At this point I doubt I can reverse this if due to vitamins. Since she's refused food for so long and now can't get up. Also, I couldn't find a diagram of their organs. Could this be eggs?
<Mmm; no... gonads are further down the body>
I mean, it's not your typical little fish so I'm not really sure where they would have... lady organs. It's weird to realize I don't know what organ is there and that could probably be a big clue.
Any advice or suggestions on what to do for her and how if any way to make her more comfortable I'd really appreciate it. Breaks my heart to see this happen and our Snowflake gets picked on by everyone in the tank. Everyone.
When she sees she snaps at them as he runs away. I don't know how he's going to be ok without her. I do know all of a sudden he's shoving herself in these figure 8 positions just to be next to her since this happened. I feel they have a 6th sense on these things.
The Snowflake also doesn't get bullied to a point it's dangerous. He's afraid of everything. My hermit crab, our cleaner shrimp, our Tang doesn't like to let him eat, he's an easy target. However, he's doubled in size so he always gets his food. I just sometimes have to give bribe food to the little fishes so they let him eat! No worries!
Thank you so much for just having a site where we can write in these questions and concerns. I wish there were more experts available for these fish. Dog or cat you just take them to a vet. But with the fish it's easy to feel helpless in these situations, so thank you.
Take Care!
<I would get and use an I2 solution like:
with or w/o actually testing. Applied directly to the water... Bob Fenner>

Re: Green Wolf Eel (Congrogadus subducens)       5/7/17
Hello Bob!
<Hey Jen!>
L'il Jen here again! Thank you for getting back to me so quickly. So I did some research on your site about iodide. I was never good at chemistry so it's a bit confusing but I think I get the gist of it. We have been dosing
the tank with Kent Marine Iodide. Is this brand ok?
Is it the same as the link you sent me to the SeaChem version?
<Don't know re their specific formulation; but very likely similar>
The SeaChem description also spoke out against Lugol's Solution, which I believe you or one of your colleagues had actually recommended.
<Mmm; not I>
So should we be looking for a different brand? I saw some measurements listed in the FAQ regarding which Iodide to use. All I see in this bottle is a guaranteed analysis of 0.0794.
<? This number in reference to what?>
I'm not sure at all of this is relevant for you in determining if the Kent Marine Iodide is sufficient.
<Is fine>
We had been dosing weekly and not daily. But yesterday I did do a daily dosing and we plan on getting a test kit ASAP to check on the levels. Will switching to daily dosing actually make a difference?
<It might well do so. The material can/does leave solution quite quickly>
Will it help speed up any chance of recovery our Green Wolf Eel has?
<Hopefully yes>
It may be a coincidence but when we checked on him today the lump had gone down substantially. It is still there but definitely not protruding as much. Every so often he does try to move but it seems like the half of him
above the lump is the only part that moves. My boyfriend believes it maybe is causing some sort of paralysis to his lower half. I'm not sure if this even possible. Does it sound plausible to you?
<Can only speculate as to the causes here... is this chromaffin tissue
involvement? Derived from what? A nutritional deficiency like B12? Other?>
We will continue doing daily dosing of Iodide once we test the levels going forward unless you advise against. I just am curious, if we find this may have been the problem, how quick should we expect the recovery to be?
<Days to a few weeks>
Would it happen right away? Slowly? I just want to be able to find some hope that it's working. Seeing him lay on his side like this is just devastating and a horrible feeling not to be able to comfort them!
<... slowly as in stated above>
I also read that if only one fish is showing symptoms similar to an Iodide problem (should I be capitalizing that word?), then you could actually rule Iodide out as a cause. Do you agree with this statement? I figure it's possible that he's just sensitive more than the others to it, and perhaps there are other symptoms that we may just be missing at the moment.
<Spelling is fine...>
One last thing, if you don't mind! Our Kole Tang has always slept in the little stone cave we bought at the store which is next to our Green Wolf Eel's cave. The Kole is not a sweet fish, like not ever. Or Green Wolf Eel
has always had the patience of a Saint when it comes to the little fish playing tough, another trait that makes him so special.
In the past, when the Green Wolf's head was too close to the opening of the Kole's "bed," the Kole would "fin slap" him repeatedly. Even with the Snowflake next to the Green Wolf, this Kole will shove his "tail fin" right
in there mouths to try and push them back. It's shocking and always shows just how passive our Snowflake and Green Wolf can be.
Since the Green Wolf became sick as I told you previously, the Snowflake has not left his side. Which means he's taken over the Kole's bed in order to be able to fit. The Kole does have another spot he alternates between at
night, so he can feel safe and is safe. He's just sort of a horrible fish.
Him and our tiny Rusty Angel run this tank. With two large Eels, the little fish are in charge. It's terrible!
Now that the Snowflake is in the Kole's home and our Green Wolf Eel is pretty stuck right at the opening of the Kole's home, he's been relentless to our poor guy. He is nonstop in both their faces, but mostly the Green Wolf. He's kicking up sand in his face, sticking his "tail fin" (right word?), literally sitting on his body, and he even pooped on him!!!
I know they can get territorial, but he's a bully, and this is crossing the line! I've had to spend time watching him and making sure he cuts it out.
Usually a finger point has always controlled my fish enough to know to cut it out. This one though, he just stares at me and keeps doing it. So my question is, what can we do!? He's clearly not a threat to the Kole and the Snowflake runs and hides quick, but the Green Wolf can't move. My boyfriend and I were thinking of moving him. I believe I read on this site about a timeout box. Using a small container of hermit crab tank. We do have one but I'm not sure how easy and stress free it'd be to take him and stick him in there. All though the idea of sticking him in a timeout box in front of all his minions, enthralls me.
<I'd catch (use two nets) the Kole and give it a "time out" in a plastic floating colander (like for spaghetti) for a day or so>
The Green Wolf is about 18 inches long. He's under rock work right now. I'm not sure how we'd go about picking him up on a good day, let alone when he's seemingly suffering from something. We don't know if that's safe to do
or even the right thing to do. He doesn't seem to bothered by the Kole but I just can't stand it. He's bullying and I hate a bully! I would go so far as to say his behavior is eerily similar to our Undulated Trigger, and they
are known as being psychopaths. He was placed elsewhere a long time ago.
Thank you again so much for this website. I again cannot express enough how helpful this website is and how nice it is to find others who understand that neurotic panic we can get about our fish. Some people point out it's
not the same as a dog or cat but it's nice to be among people who know that's not true and take it seriously. I also love your tell it like it is approach with some who can be a bit difficult. Especially the ones who refuse to follow grammar rules!
I hope my grammar is up to par! I may have jinxed it now. I also want to point out I may have kept saying him with the Green Wolf and previously her in the last email. The color indicates it is a female. However, we've
always used the pronoun him and I try to be accurate when writing in, but can easily forget.
Thank you so much and I hope you enjoy your weekend. My fish give a big thank you too, for your care and help to all the fish everywhere!! I apologize for all the words in this email too. I always try to say just a little, and it never works out. I'm Italian and from Jersey so it's a very talkative combination. I apologize!
Take Care!
"L'il Jen"
<Cheers dear. Bob Fenner>

Re: Green Wolf Eel (Congrogadus subducens)     5/9/17
Hi Bob!
<Diminutive Jen>
Thanks for getting back to me again so quickly. I had been daily dosing Iodide for the few days since we originally spoke and I swear the bump went way down.
<Ah yes; tis a real cure>
Even now it's not very noticeable. However, some time in the past 24 hours, he's developed these white patches/sores. I searched a bit, and nothing is worse than looking up spot or white anything with fish. All I ever get back is Ich. I found a few things matching some symptoms, progressive lost of appetite, laying on side, lump, sore, but not all of them.
At this point, while I was hopeful for the chances of a recovery, I no longer am. His color has diminished, he seems incapable of moving the lower half of his body, the sores could only be the beginning, and I feel he's just in a state of suffering.
<Mmm; I would not give up>
He started off with the Snowflake Eel in my boyfriend's 55 gallon tank.
Which he upgraded weeks later to a 75 Gallon. My boyfriend's care in the beginning was typical of probably most beginners. He thought he knew enough and rules be damned. But Douche (Green Wolf Eel), and Snakey (Snowflake Eel), amongst others, roughed it out. Once I took over they grew and thrived, with rules in place and all advice taken!!
I just don't know in over a year what could have brought this on. I don't know it matters for him at this point. But if it has something to do with my care or a mistake I made, I couldn't live with myself. I've got others in my care and it just scares me that they aren't being given the care they deserve. From previous write ins to your website, I've never had a mistake pointed out. But, is it possible that he is suffering from something that just isn't affecting (effecting?!) the other fish?
<Possible...? Yes>
Everyone else has their appetites, their energy, we've had breeding of snails and cleaner shrimp, and I'm told breeding is always a sign of a healthy tank.
<Usually one end of the spectrum or t'other>
We've got a fair amount of hitchhiker type worms and snails as well as store bought. Growth on rocks and algae on the glass, another indication of a well off tank. The water clarity is good and my boyfriend tested this weekend and found the water parameters are all within the necessary range in the booklet (API Test Kit).
I know it's like literally just pulling stuff outta you know where for you to guess what's gone wrong. At this point I feel what I need to be focusing on is what to do next. His wounds in his condition regardless of origin in assuming just add to his diminishing chances. I've enclosed photos. From your experience, do these seem to be bite marks? I thought it looked more necrotic as the rest of his skin in the light just looked not healthy. I enclosed a photo of lump as well as his surroundings.
<Could be something internal, parasitic... genetic. Some Congrogadus do well, some do not long term>
I've noticed the Kole Tang hanging there as usual since it was his bed, but I swear he's got a malicious look on his face while he's over there. I'm currently keeping watch in our tank to see if I can observe anyone picking
on him. I know what puffer bite marks look like, and it wouldn't be Snakey, only other fish tank mates are a File Fish (Aiptasia eating kind, not sure of scientific name), and a Rusty Angel. I don't see how they could bite in that way.
My boyfriend suspected maybe bristle worms because he's been laying in sand for so long, but I don't know if I see them coming out of rock like that and onto him. I also stay up sometimes very late. I check the tank
periodically sometimes until morning and haven't noticed anything on him like that. I also don't think the Kole Tang has the guts, but I do think he's evil. If it does look like bite marks we'll be "locking" the tang up immediately.
So, aside from the frustration invented and desire for identification if what I'm looking at is necrotic flesh, or bites (please!), there's just one last thing I'd like to ask.
I'm thinking that because of his suffering and the state of his condition, perhaps euthanasia is best at this point. I'd want the same for a dog in this condition, and I believe my fish deserves the same consideration. I read your site and I know Clove Oil is recommended. I know you advised 30 drops. Is that the same with a fish this size?
<Yes; or more... >
He's 18 inches long and I'm not quite sure how to convey the girth properly. Also wondering, is it ok to just take the rocks apart and grab him, gently of course? We are due for a water change and I told my boyfriend to hold off. They stress me out worrying about it stressing my fish out. I hate the way some people and some in pet stores just stick their hands in and move stuff around with fish in there.
So naturally, thinking about how we get him out and it scaring him, scares me. I enclosed a picture to show just exactly his position. It's not going to be possible to net him as if he were moving, will it? I never netted the big ones so maybe I shouldn't speak to it, but he's just a big guy. I don't see we can do that.
<Easy to remove with a large net if this is what you want to do>
Should my boyfriend use his hands? Is it safe?
<Could and is safe, but I'd use a large net>
Should he avoid the wounds as much as possible? It's killing me to do this!! I know our Snowflake we have to watch out for if putting hands in because they have dirty mouths and can cause serious bites. But if it seems he can't move his lower half of his body should we be ok doing so?
I just do NOT want to hurt him and I hate the thought of scaring him before passing, but I just know if he's suffering it's the lesser of both choices.
It's the right thing to do. Would it be advisable to get a pair of those gardening gloves they recommend for handling the rocks? The really long ones that go past your elbows?
<Dishwashing gloves; long ones, are better>
Sorry for all the questions. I just don't want to do the wrong thing and cause him poor pain. As of now, all the fish are their normal selves, Douche was/is the hardy one, so I'm assuming it's unique to him. I know, you shouldn't assume.
Once we saw the wound though, my boyfriend thought maybe this was parasitic in nature. Warned me against putting my hands in the tank. I have to feed my angels (all the inhabitants of tank), so I stuck my hands in! Narrow
Lined Puffer, Douche, and Snakey are target fed with tongs. So far nothing's crawling out of me, so I'm assuming I'll live another day. If it were parasites, would they be a danger to me? If it were, would it have become so dire so fast?
<You won't catch anything from the fish, or tank water if you don't have cuts, breaks in your skin>
Just to reiterate, he stopped feeding a month ago except for a piece of food here or there. Literally, he'd have maybe 1 piece of silverside once a week or every two weeks. Then laying on his side, although could switch
positions, then to the lump and possible paralyzation of his lower half below the lump, to now having sores. All after the hunger strike started exactly one week ago.
I'm not worried about me so much as them and especially Douche's suffering.
So if you can basically just share with me your thoughts and opinions on what should come next. I want his suffering to end. It just kills me to watch this. He was a truly extraordinary fish. Truly. To see him so defeated is a somber reality check. Makes me think of the millions of fish in the oceans, all in jeopardy of a similar fate as the oceans get warmer and toxic.
I always try and remember how lucky we are to have these fish with us now.
I try and remember that while I don't necessarily agree with how many fish we take out of the water for the aquarium trade, and how careless some can be with them, that some of these species days can/are numbered. At least I get to witness it up close just how incredible they all are. Right down to the little peanut worms.
Thank you for help and kindness and understanding with my many questions.
Thank you for understanding that it always helps to have a pro tell you what the right thing to do is! I often worry I'm not educated enough to be taking care of them, so your guidance and that of your colleagues is essential to providing the proper care.
Take Care!
<The choice is up to you. I shy on the side of being conservative in such matters; waiting, hoping for the best>
PS: I wrote in months ago and had told you I couldn't find the option to go to the next page on the WWM Google search results page. When searching again I noticed it using my cell phone browser (Safari), and my tablet
browser (Chrome).
However, even though it looked the same as desktop, I figured that could be it. So when I requested a desktop site using Chrome on my tablet, the page reloaded with the page numbers showing on the bottom for me to get to the
next page of search results.
I just wanted to pass that along in case someone wanted or needed to know.
I know a lot of people probably use cell phones or tablets or iPads and may run into the same problem. Not a huge thing. Just helpful to continue browsing the results! Thank you again for everything.
<Certainly welcome Jenelle. Bob Fenner>

Green Wolf Eel Growth      1/20/17
I wrote in months ago regarding a Hawaiian White Spotted Toby with damage to the eye and you provided much needed advice! Unfortunately, she passed away a week later. She was in pain so it was for the best. I'm grateful for this site and being able to ask for help on something without a fee (like so many websites nowadays) is incredibly generous. So thank you again and in advance for any help provided!
<Certainly welcome>
I did do a search on here for the problem I'm inquiring about but could not find anything related. Also, on your website when running Google search I couldn't find a way to go to the next page of search results. Was this just me?
<The "next page"? The links on our pages should all be functional. Was this on Google's work?>
I also searched Google and could not find anything either. My problem has to do with a white bubble appearing on my Green Wolf Eel
<I see this in your excellent photograph>
and of course results were coming up as anemones, when I tried to eliminate those results having to do with anemones or corals all I got back was Ich.
So I tried and I apologize if the answer is hidden somewhere and I missed it!
The details are- we've got a 75 Gallon tank and one of those inhabitants is a Green Wolf Eel (not a real Eel, so many names not sure which one to use!)
<Ah, yes; a Pseudochromid... MANY fishes (even non-fishes) called eels for having long bodies...>
named Douche. I'm sorry for the bad word, we thought he was kind of bad when we first got him. It's an ironic name now because SHE is actually as sweet as can be. Very motherly. But I say he so ignore the misuse of pronouns!
Douche is attached to the hip with a Snowflake Moray Eel named Snakey.
Snakey doesn't breathe without seeing if Douche does it first. Snakey doesn't sleep without Douche, usually tearing the sand up to make sure he can fit underneath Douche.
We have no corals, just live rock, and no Lion Fish. I noticed yesterday a growth on Douche's face. It looks like a giant white head! Or a puss filled wound. But I'm not sure if they can even get that as fish. His eating is fine. He ate last night, his silversides,
<Do broaden this diet... it's deficient in B vitamins... Needed by all life on this planet>
like always and he was fine. We do have a serious picky eater problem in our tank. We dose with vitamins but any attempt to soak their food in vitamins has failed for Snakey and Douche.
<? Well, if placed in the water, ARE getting inside your marine fishes>
If I could get Douche to eat it then Snakey will. So I feel that may be relevant in case this is related to diet. If so, any other ideas? When I do try forcing it he bites it, shakes his head, goes to the glass where I am, and then spits it out. Spiteful!
Douche does like to do this thing I call "chasing his tail." I can't find a lot on Green Wolf Eels but from observing him a lot and I literally mean hours every day for the past year, it's totally normal. He just swims in circles and puts his mouth on his tail like he's trying to eat it.
Identical to a dog. Very dramatic, tends to do it near dinner time. I feel like he's just saying "I'm so hungry if you don't feed me I'll eat my tail!" He gets fed everyday. However, sometimes he does this spinning in tight spaces and I hear him hit his face against the glass or a rock. I'm not sure if this will end up being relevant or not.
He's large, maybe 14 inches (I'm really bad at guessing that stuff), he hides under rocks usually with Snakey, comes out same time everyday when he knows it's time for food. He's a gentle giant. He will eat fish that fit in his mouth but at the same time it's like he knows who he can't eat.
We've got a File fish (the one they sell for Aiptasia)
<Likely Acreichthys tomentosus>
and while he's grown a bit he's still somewhat bite sized, but Douche never tries and they actually end up sharing a cave often. The File Fish has actually gone for silversides that Douche has in his mouth!!!
I don't believe this to be Ick at all because it's just this one spot. Like I said I'd refer to it more as a bubble. I can see it is raised. He's behaving normal, eating, pooping, playing, sleeping, as he always does. I just want to know if this looks like something to be concerned about or maybe a disease I didn't stumble upon yet. I don't think it could be a bite and again we have nothing that stings. We've got two Cleaner Shrimp, 2 Camel shrimp and a Coral Banded Shrimp who take care of parasites (I hope they are doing their job), so I'd hope that risk is minimal.
(I know those shrimps seem like a bad combination, but the 4 of the little ones actually share a rock together, and our Snowflake would never eat them because he's terrified of his own shadow. When he sees a shrimp he runs and hides under Douche. He's "special." The Coral Banded does try to get the shrimps but for 7 months now has yet to succeed.)
<Will likely in time. Perhaps during a molt>
We just did a water change this weekend. Our pH is 8.2, Ammonia is 0, Nitrite 0, Nitrate 0, Salinity 1.022.
<I'd raise, this, keep near 1.025>
Douche and Snakey are the only remaining members of our "Original Members," the others were a Lion Fish who passed last year, the Toby, and an Undulated Trigger who we realized was the Spawn of Satan (my boyfriend picked him before I knew anything about saltwater tanks or fish, what a shock he turned out evil!!!).
It's important to me that he stays healthy and happy. He's the greatest and so smart and it would kill me if anything happened to him, but most of all it would kill Snakey. When our Toby passed his best friend our Immaculate Puffer totally changed his personality. He didn't swim a lot, he hid all night (which is actually normal but with Little Puff they played all
night), he was never the same. I'm afraid the same would happen to Snakey.
He doesn't feel safe without Douche.
I take care of them daily and my boyfriend maintains the tank. I'm incredibly involved and I just can't think of anything that changed or anyone in the tank who could have caused him harm.
I'm attaching a picture and I appreciate you taking the time to read my rambling on and for having this site in general! I spent hours the other day reading all your FAQ's on all my fish and it is so informative. Thank you for the information!! I'm so sorry I talk so much!! :)
<I fully suspect this "growth" is resultant from a physical injury... a "bump in the night"; and will likely cure itself in time. I would NOT treat the water, but continue on the schedule you list here. Be of good life. Bob Fenner>

Re: Green Wolf Eel Growth         1/21/17
Hello Again!
<Hey "Little Jen">
Thank you so much for the quick response and reading all my many words.
Since I wrote you which was when that picture was taken.... the "thing" changed. I swear it looks like a pimple! Now it looks like a popping one.
<Ah yes>
Does this change things?
He's waiting for me to feed him as we speak. He came from the back of the tank to the front when he sees me and knows it is time for food. So good thing, I guess. I'm attaching a picture of the change. I'm hoping the guess on it is still the same and it's not some sort of scary monster parasite being born.
Thank you again a million times!
<Cheers, Bob Fenner>

Green Wolf Eel Compatibility   4/2/12
Hey Bob and crew!  I have been pondering a Congrogadus subduscens for a while now. I have a good grasp on this unique fish but am unclear as to invertebrate tankmates. I know they will decimate shrimp, crabs and hermit crabs. I have however, had no luck finding information as to how one would get along with larger snails or urchins.  Thanks, Josh
<Hard shelled Gastropods should be fine, as well as urchins. Bob Fenner>

Lionfish/Wolf Eel? comp. -- 08/05/09
While I feel like I should be able to answer this question from my own common sense/experience, I nevertheless feel like I have to ask: I have found a very nice green wolf eel about 6-8 inches long at a local pet store that I want to buy for my fish only tank; however, the tank has two Lionfish in it at the moment, a 5-6 inch Dwarf Zebra one that is very docile and quiescent, and a rather vivacious 6-8 inch Volitans. From past experience I would say that my Dwarf Lionfish is generally the one that approaches cleaners I put in the tank (Arrow/Hermit crabs...unfortunately I've had some bad luck with Arrow crabs and the Lionfish's food turning the crabs into food) and tries to stare them down, while in general I've never seen the Volitans do that. However I do not think the Dwarf's mouth is large enough to swallow the Wolf Eel, but the Volitans mouth can definitely open wide enough to envelope the head and obviously the tail to the eel.
<See, you already answered the question from your own common sense/experience. If it can be swallowed, it is endangered.>
I heard from a friend that so long as the eel is longer than the Lionfish, there shouldn't be a problem, but the Volitans and Wolf Eel are basically the same size. Because the store's tanks are tiny cubicles, I highly doubt the eel will grow any more while there, and the only other tank I have is reef tank, so I couldn't put it in there for a while.
<I'm sure it will grow, but slowly.>
The store employee suggested putting a tank divider in to separate the animals until the eel grew large enough, but my tank is a 55 gallon bow front and dividers for that are hard to find and would separate the tank in a way that would severely limit the space for my active Volitans.
<I would not add another fish here. It will even become narrow for the larger lionfish with time.>
I suppose the easiest option in this dilemma is to forget about the green wolf eel, but it is a very tempting creature, very bubbly from what I've seen and heard of the specimen that's been in the store for a while. And while I'm not so concerned about this, what would your opinion about placing a Green Wolf eel in a Lionfish tank-
<A larger eel in a significantly larger tank: maybe. If the P. volitans was removed from your tank: maybe. Your current setup: I wouldn't.>
have green wolf eels been known to pick at Lionfish like Angels and Puffers do?
<No. Cheers, Marco.>

Green Wolf Eel, fdg.  4/18/09
Can hole/frozen Anchovies be used for feeding rather then say, silversides?
They are not frozen in any kind of brine
<Anchovies certainly could be used occasionally if they're accepted, but because they're so oily, it would be unwise to use them too often. Partly, the large amounts of oil could harm your fish, but also oil tends to make a mess of water quality. So by all means try them out once a week, but don't use them as a staple. Much better to concentrate on a mix of white fish and invertebrates, in particular species without thiaminase and with low fat/oil content (see WWM re: these issues for more). Congrogadus are fairly adaptable fish, but will go off their food in the "wrong" tank. Cheers, Neale.>

Wolf Eel System\(Over)Stocking\Health\Feeding. 3/20/2009
<Hi Chris>
I have had this little (big about 13in) guy for about 5 months.
He is in a 55gl. tank with lots of live rocks and caves. He lives with a:
Lunar Wrasse about 11-12in long
<Needs 75 gallons as an absolute minimum.>
a Huma Huma Trigger about 5-6in and a Fox face Rabbit fish about 5in.
<You are severely overstocked.>
All has been good, until 2 days ago I noticed that its left eye had a bright green glossy tint to it about the same color he has on the top of head (his body is a dark greenish-brown). Now today the eye is still a
glossy green but it looks like it may be swelling up some.
<Likely a physical injury>
He is still eating OK, his sight seems unchanged, he sees if I hold a gold fish up to the glass.
<Please tell me you are NOT feeding him Goldfish, one of the worst foods available. Read here: http://www.wetwebmedia.com/goldfshfd.htm and here:
http://www.wetwebmedia.com/ca/volume_6/volume_6_1/thiaminase.htm .>
The other fish don't pay any attention to him so I don't feel that he is being picked on.
<That you can see, Lunar Wrasses are very aggressive.>
Not sure if this is even possible but, the only thing that I can come up with is that with the color being a bright green is algae. could algae start growing on a fish?
<It is possible, but unlikely>
The rock he is under most of the time does have a lot of Hair Algae on it.
<What are your water parameters, filtration and skimming?>
Any info would help. Also I attached a picture, sorry I used my cell phone.
<Need a better picture than this , cannot see any real detail.>
Chris in WA
<Mike in FL>

Demon Green Wolf Eel... moray? Not the Pseudochromid/Congrogadid  12/11/08 Hello, <Hi Ralph.> I hope you are all doing well and enjoying the Holiday season. I have done quite a bit of research and was hoping you might have some suggestions for me. I have a Green Wolf Eel that I rescued from a friend who had it in too small of a tank. I have relocated him to a 55 that I had up and running sitting empty. He is doing fine eating well, perhaps a bit too well. I have tried to add other fish to the tank with no luck at all. I made sure he was fed and the light were off in the tank and his snack list is costing a small fortune. Several various damsels from 3 stripe, domino and inch long Sgt. Majors. They lasted less than 5 minutes. He was able to take out an Atlantic spiny puffer in a week and even did in 2 different lion fish. He is relentless with hermits, takes chunks out of Chocolate Chip Starfish and if you blink any species of shrimp is gone. Ok well I have not tried a Mantis Shrimp yet but you see my problem. Any suggestions on what I might be able to try in there with him that might stand a chance of living a bit longer than a week? I have quite a bit of rockwork and a clear PVC tube that he sometimes likes to hide inside. I know I could relocate him to another tank, stock the 55 and then place him back in the 55 after the other fish have settled but wanted to know if perhaps there were any other options. Certainly the cost is adding up. I was thinking of a Niger Trigger but after he took out the puffer and lion I was hesitant to add them. Thanks so Much and please be sure my Green Wolf Eel gets put on Santa's Naughty list. Ralph <Almost sounds like a Green moray eel, not a Wolf eel (Congradus sp.). The problem here is that recommendable fish large enough to be safe from the wolf eel would be too large for the 55 gallon tank. If you want to keep it with tank mates, I'd recommend setting up a significantly bigger tank with fishes too large to swallow and introduce the eel last. It also sounds as if your eel needs more food, generally Congradus eels are not that bad mannered. In larger tanks they can be kept in pairs or small groups, and have been bred in captivity. Cheers, Marco.>

Green wolf eel and Jeweled Moray 07/03/08 Hi everybody hope all is well... <Hello Josh.> So at one of my local LFS they have this beautiful green wolf eel (Congrogadus subducens), it is beautiful, strangely it is red in color. <Yes, they sometimes occur in this color. There is some variability, and in addition they are able to change their color to some degree.> instead of green and it is about 12 inches long and as think as a ping pong ball. At home I have a jeweled moray who is about 22 inches long and as think as a tennis ball. My question is would I be able to put the green wolf eel in my tank without it becoming a quick snack for the jeweled? <I have seen this combination, but with animals of equal size. Personally, I would not risk losing the Wolf eel, because it would likely fit into the M. lentiginosa.> Thanks for your time. Josh <You are welcome. Marco.>

Carpet eel blenny not eating please help  10/2/07 Hello, Thanks for all the information you have provided since I started in this hobby. It has been a great help. My question is about a carpet eel blenny. <Congrogadus subducens... sometimes placed in a subfamily w/in the Dottybacks...> I have had him for about 5 months. He has been doing great. He would come to the top of the tank when I would look in and loved to eat. <This is a great aquarium species... very intelligent... interesting behaviors> I have been feeding him once a day due to my schedule. He would eat three or so decent size pieces of krill each day. I give him small pieces of raw fish whenever I am eating it for dinner. About a week ago he started staying in his PVC cave I put under the sand bed. he barely comes out now. He has only eaten two pieces of krill in the past week. I have tried offering him silversides and a hunk of orange roughy but he did not want them. He snapped at the silverside but then returned to his cave. I have noticed his lower lip is now a reddish orange color now. I was not like that a couple weeks ago. When I feed him I put the food on the end of a bamboo skewer. Is it possible he got stabbed by the tip while feeding causing the reddish lip? <Mmm, yes, possibly> I don't know what to do or why he is not himself. Please any suggestions would be much appreciated. <I suspect some sort of nutrient deficiency might be at play here from the mostly limited list of fatty foods you list... Do you supplement these by soaking?> My tank parameters are the same that they have been for the past year or two. Ammonia is 0 ph is right above 8 and nitrates are somewhere under 10 parts. Salinity is at 1.24. He is in a 30 gallon <Small...> with a three stripe damsel, a scooter blenny, a conch, two snails, and two hermits. He is about 6 or 7 inches long right now, I am currently planning a new 100 gal home for him. <Oh, much better> The tank temp has been a little lower then normal, 76, since it has been colder. I just got a new heater today to help stabilize the tank at 79/80 like it is normally. <This should help> The tank temp has been around 76 for about a week or a little longer. Thanks for you help and for this great site. I am sure it has save many lives. Kind Regards, Jeff <Do use an appetite/immune system booster like Selcon, Biovit... directly to the water and on the foods for ten-fifteen minutes before offering. This fish may also be "going through a phase" (like reproduction) and just be reclusive due to this. It should resume feeding in a week or two. Bob Fenner>

Re: Carpet eel still not eating, Congrogadus   11/21/07 Hello again, <Jeff> I took your advice and I ordered Selcon and vita-Chem and received them about a week ago. I soaked the food, (krill, clams, silversides, salmon, Mysis, brine) in the Selcon. I added the recommended amount of Selcon fifteen minute prior to feeding and dose the tank as recommended. I also added vita-Chem as directed. My carpet eel will still not eat. it has been about a month now since he has eaten. <Don't give up faith here! Have seen this species go off feed for months> He does not move around that much, just alternated from his three favorite spots in the tank. I have done a 40% water change and leaned all the filters this past week. I do 30% changes every two weeks on a normal basis. 0 ammonia, nitrates under 10 parts, 8 ph, and 1.25 specific gravity. <Missing a decimal space> The temperature is between 78 and 80. The red spot I mentioned in my earlier email has since disappeared. My eel looks healthy with no signs of disease. He perks up when I look in the tank but will not eat. Is there anything else you can suggest to get him eating? Do you have any thoughts as to when he stopped and how long he might make it? I hate to see him not eat and don't want to loose him but I don't know what else I can do. Thanks for all your help in trying to save this amazing fish. Jeff <Again... to continue doing what you are... I do think/sense this specimen will resume feeding in time. BobF>

Green wolf eel is black  8/16/07 Hello all, About 2 months ago I bought a Green Wolf Eel for my high end brackish tank. When I got him he seemed healthy with the exception of what looked like scraping on the end of his tail. I believe this was from entering/exiting an undersized fake coral cave at the pet store. it has taken a while to heal up but it pretty much ok now. The Wolf Eel seems happy. He alternates between hanging out in the live rock and venturing out into the tank. He is a greedy eater and is somewhat aggressive at meal times. <Yes, good signs for this Congrogadid, latter day Pseudochromid> He shows no sings of illness or stress..... except that he is pitch black. <This IS a sign> all the time. He is never green anymore. At first I assumed it was due to the black sand substrate. So I changed it to a lighter color sand. This didn't help. He is still black as night. specs90G, Rena FilStar XP3, Magnum HOT, Turbo Twist UV Ammonia and nitrites are at 0Nitrates are a little high at around 60 but I don't think this is the problem.SG is at 1.020PH is 8+Tankmates: scats, monos, green spotted puffer I am adding Live Rock as I acquire it and have about 30-40lbs so far. Diet is mainly silversides and krill. He will not take flake or pellets so far. The color change was abrupt and not a fading. Salinity is ok as they are brackish in the wild. He is not bullied and has no injuries except some residual scraping as noted above Any thoughts on why he is black? thanks so much! <In a word, stress... this is really a marine organism for one... s/b in spg of 1.026 or so... The puffer may be nipping it... I'd try moving it to a full marine system. Bob Fenner>

Please do send along a brief bio... and the Congrogadinine -- 03/17/07 <Ah, yes... Will post. And you're having no problem/s logging on?  BobF> Nope, none at all. I'm working on the freshwater/brackish blennies piece, among other  things. Specifically, I'd like to canvas your views on Congrogadus subduscens. Admittedly, not a blenny, but called one, so I've included  it on the basis that it occurs in brackish water (apparently) and I  know aquarists who keep it with monos & scats at SG 1.016. <Ah, yes... the errant Pseudochromid... in its own subfamily still I believe> You know  more about Indo-WP fish than I do -- is this fish a transient member  of brackish water communities, or a euryhaline species suitable for   high-end brackish tanks? <Have never encountered this species in the wild, nor heard reliable accounts on how it is collected. The short answer, "I don't know"> Fishbase confirms its brackishness, but I  can't find any scientific papers on salinity tolerance, which is my  usual _modus operandi_ before "declaring" something a brackish water  fish. <Good to be cautious. Cheers, BobF> Cheers, Neale

Wolf eel Eggs - 10/15/06 Good evening, folks. <<Hello>> I have written before a few times about our beautiful wolf eel, which recently survived our family's relocation from California to the DC area. <<Ah, good>> Wolfie, a beautiful orange aggressive creature, stopped eating about a week ago, and then yesterday, we were all surprised to find this large pink batch of eggs that she (! We had always thought of Wolfie as a male, since the bright orange coloration defied the black/green distinction in the literature) was protecting. <<Hmm, just musing here...I wonder what biological "cue" caused the eggs to hydrate>> Obviously the eggs are not fertile, but what should we do with them? <<Best to remove them before they begin to decay>> Will Wolfie start to eat again soon? <<Likely, yes...and removal of the eggs may speed this>> Wolfie shares a 55-gal FOWLR tank with a small Volitans, a coral-banded shrimp, a choc-chip sea star, and a sea urchin. Thanks for your help and the amazing information provided on your website. <<Glad to be of service>> Franck <<Regards, EricR>>
Re: Wolf eel Eggs - Thanks for the insights, Eric.  - 10/17/06
<<My pleasure>> I thought you might be interested to learn that the problem took care of itself.  The circle of life and all that.  The Chocolate Chip sea star found its way to the eggs and made fairly short work of them in two separate feedings. <<Ah!  Better than 'tossing them'>> In between, Wolfie moved the remaining clutch around a bit with her mouth, but didn't move far from the original site. While the fish has not yet resumed eating, her behavior is returning to normal. <<Excellent...perhaps you can tempt her with some frozen glassworms.  I find these to help with most finicky feeders>> I assume that the eggs were a healthy meal for the ccs? <<That they were...>> Thanks again for the quick reply. Franck <<Always welcome. EricR>>

ID please - Green Kelp Poacher or something!  6/25/06 - Hello, Hi there, Leslie here with you this evening.> A friend asked me to help identify his new fish. It is something I have never seen before. A green kelp poacher is what he was told it was. <Hmmm, interesting name and not one I have heard before.> The fish is about 1 foot long bright green looks like a Moray but has a head that is shaped differently. I have looked in all of my books and the web with no luck. The head looks more like a Gramma. The fish cost him $150.00 bucks. I try to tell him don't buy anything unless you know what it is and what it eats. <Very good advice!> Do you have any ideas of how to identify this fish? <Hard to say without a photo but it sounds to me like it could possibly be Congrogadus subduscens commonly known as a Carpet Eel Blenny or Green Wolf Eel. You can have a look here http://www.wetwebmedia.com/pseudoch.htm. They are a Dottyback , Family Pseudochromidae.> He just told me that the fish is hiding under his rocks and has not eaten yet. <They are much more secretive and less bold than the other Dottybacks and hiding under rock would be expected. It probably needs some time to adjust to it's new surroundings. They are carnivorous so meaty frozen and fresh meaty seafood would be appropriate. You can find captive care information at the link listed above.> Thanks. <Hope this helps, Leslie>

Eel Blenny/Pseudochromid Question... with Dwarf Lions OK, with a Queen Trigger, No Way   6/17/06 Hello, I have recently come across a Eel Blenny/Green Wolf Eel (Congrogadus subduscens) at the local fish store, but have been having some difficulty in finding info on it.  I've read that it gets fairly long in length, but despite its size is quite passive as a Dottyback.  Can you please reconfirm this? <Please see here: http://www.wetwebmedia.com/pseudoch.htm> How passive is it?   <Quite... maybe a 2-3 out of ten...> In my tank I have two dwarf lionfish (at the moment, inedible size).  Would these fish go alright together in the future? <Should, yes>   I also have a decent sized queen trigger.  Any problems there? <!Huge... Balistes vetula is close to a "ten out of ten"... Not to be trusted with these other fish species. Bob Fenner> sincerely, Aaron Raney Green wolf eel I saw a green wolf eel in the LFS they said it would not eat hermit crabs and was not in the moray eel family. Do you know anything about this type of eel? <Yes... as bizarre as it may seem, this is a member of the family of Dottybacks, Pseudochromidae. Please read here: http://www.wetwebmedia.com/pseudoch.htm This species is covered here. Bob Fenner> thanks, j Colgan

Green Wolf Eel Spawn - 02/03/06 Eel has eggs any recommendations?  I have a pair in the tank along with a trigger.  I am taking the trigger out to another tank, but how long is gestation?  Any help would be good. <<I'm sending you a link to a chat forum where someone is in their third spawn with this fish.  You should be able to get the info you seek...even ask specific questions re this topic.  Regards, EricR>> << http://www.columbiamarineaquariumclub.org/forums/index.php?act=ST&f=19&t=1488&s=645d1c240337198ac41a0a01a34fa14c >>

Help, we have Eel eggs! Dottyback repro.   1/18/06 I have a green face wolf eel. She just laid a bazillion eggs. We have had her for about 1month and the pet store had her for about 1month. How do they fertilize their eggs? Will they hatch? As far as I know she has not been around a male eel. <Then these are sterile... will not hatch... may want to vacuum out before they pollute your water> We have other fish in the tank. Should we move the eggs or move the fish? Help!!!!   Thanks,   Heidi <... If you have earnest desire, please see WWM re Pseudochromid Repro., the works of Martin Moe. Bob Fenner>

Snowflake moray and a green wolf 2/11/05 Just a quick one, since I can't seem to find anything on this anywhere, maybe you guys can answer it for me. Would a Snow flake moray and a green wolf ell be able to coexist in a 46gallon bow front tank? Thanks in advance Nick <its rather poor mix... the green wolf "eel" is a fast and furious eater (keep sighted) while the moray is not. Without target feeding the latter, it may suffer over time. Do reconsider. Anthony>

-Green wolf eel with an appetite for flesh- We're having a problem with our Green wolf eel. It has eaten 2 Lunar wrasses 1 4 inches and the other 6 inches. <Ouch!> The eel is 14 inches. Would a Niger Trigger fish be OK with it or can you recommend another fish? <Triggers are pretty precarious to swallow, but you may want to choose a more aggressive species. this selection would depend on the adult size of the trigger and the size of your tank.> We also have a Dog Face Puffer and a Yellow Eyed Tang. The Puffer and the Tang seem to be fighting also. But I think it more of a territorial dispute since the Tang is new. <If the tank is too small, they may dispute indefinitely. Since the tang is new, however, a little bickering is expected. Hope this helps! -Kevin> Any help would be appreciative

Green Wolf Eel/Pseudochromid Dear Mr. Fenner, I have a green wolf eel and I cant seem to find any information on it. can you help me?  <A little perhaps... this fish, Congrogadus subduscens is actually classified as an Eel blenny (subfamily Congrogadinae) of the Dottybacks (family Pseudochromidae) of the tropical Indo-Pacific. It's actually not an uncommon offering in the trade... and generally takes most all types of meaty foods with little training...> I also have 2 lion fish, I cant seem to get the one off gold fish, I tried starting him on frozen foods, he would not eat them, I gave him gold fish and he loved them. how can I get him on frozen?  the other lion fish eats it but he wont. and are silver sides a good food or are they the same as gold fish. well, those are my questions. thanks again, Mike Mastronardi <Please read over the "don't feed goldfish" and Pseudochromid pages and FAQs posted on the www.wetwebmedia.com for answers to your queries. Bob Fenner>

Spawning Green Wolf Eel, CCS health Hello! I have a question about something that happened that completely threw me for a loop. I have a green wolf eel (about 6 months now) that I had always believe to be male due to the fact that it is an extremely vivid green color. I had read that females tend to be duller and brownish in shade. <Yes... a gorgeous, interesting Pseudochromid species> However, when I came home today from school, I found my eel blenny to be wrapped around a purple egg mass, so its female, right? <Sounds like it> I don't know where to find a male eel to fertilize my eggs and even if I did, I wouldn't know what to do. <Uhh, too late for this batch> So what can I do now? I obviously can't leave the mass in there, can I? Would it be safe to remove the mass? <I would wait a day or two... then siphon it out> And if so, when can I do so without upsetting my eel. (I've recently moved the eel into this new tank about a week ago so I imagine it's a bit stressed.) <Better to upset it, than risk the water pollution consequences> I also had another question regarding my starfish. I have a chocolate chip starfish that was being kept in a tank with two hermit crabs. <Ummm...> Recently, I acquired another hermit crab that was sized in between my two current ones. I noticed that this crab was more active than my others. about two days later, I found my starfish flipped upside-down and curled up. After further examination, I found that two of the "chips" on my starfish had been eaten off. the first thing I did was remove the three hermits and then I quarantined Callisto. I have been carefully monitoring the starfish, and it seems to be doing better as its moving around again. Is there anything else I should do to ensure Callisto's welfare? <Please read on WWM re CCS> Thank you so very much! ~Jules <Thank you, for writing, reading, using your spell- and grammar checkers before sending. Bob Fenner>

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