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FAQs about "Freshwater" Morays Eel Behavior

Related FAQs: "FW" Moray Eels, FW Moray ID, FW Moray Compatibility, FW Moray Selection, FW Moray Systems, FW Moray Feeding, FW Moray Disease, FW Moray Reproduction, Marine Moray Eels

Related Articles: Freshwater Moray Eels by Marco Lichtenberger, Freshwater Moray Eels, Moray Eels, Other Marine Eels, 

Spaghetti Eel... which reminds me of bugs bunny    11/9/18
Good day Neale, Marco and all you good people in WetWebMedia,
Neale, I remember this chat in fishforum, many many years ago (2006)
In the chat you are advising a brackish aquarist to get an Echidna Rhodochilus (I already have it) and/or Spaghetti eel.
<Ah, yes. Back when I had time to do online forums! A distant memory, sadly.>
Well, since I already have E. rhodochilus (a model citizen, very nice, stay small and docile),
<Yep, this is the usual experience.>
and I have given away most of my eels to other eel lovers (except for my E. Rhodochilus), I decided that I still have room for small slimmer non-aggressive eel, so I asked my procurer to get me a Moringua raitaborua.
What he ended up sending me are these two eels (pictures included), which a bit surprising to me. What bizarre eel, I thought, when I saw them first time. Body like Monopterus albus, paddle-like tail (like some kind of fish.. well eels are fish anyway), face like moray... but they behave more like Bugs Bunny!
<The paddle-tail is presumably to help with digging. As you're seeing, these fish are extremely happy when half buried in the sand.>
That is, not long after I plunge them to my aquarium, they immediately burrowing! I just turn my back for a short while, then as I look back, they already gone beneath the sand. They stuck out their head every now and then (like Bugs Bunny!), but every time I bring my face closer to my aquarium, they will pull their head back in and swim underneath the sand, making curious patterns. Even my white cheek moray got confused (I think ;) ) as it remained home and not coming out at all.
So, are they Moringua raitaborua? But they are not pink, their color are more like Monopterus albus. The smaller one is about 30cm in length, the bigger one is about 40cm. They have slim bodies, shaped like Monopterus albus... kind like spaghetti :D so the name is proper. They are caught in a freshwater river several kilometers away from the estuarium, and they were being kept in freshwater for months before my procurer bought them and send them to me. Maybe M. raitaborua change colors when they grow bigger? or maybe they are M. microchir? but isn't M. marine eels?
<It's really hard to say. The pale colour could easily be down to the light coloured substrate -- many fish adjust their colours, becoming paler if the substrate is pale. I'd be looking at the pictures on Fishbase for a start:
While both occur in brackish water, as you say, of the two, Moringua raitaborua is the one more associated with fresh and brackish conditions, and presumably the more adaptable in the longer term, Moringua microchir being more marine when adult. That being the case, I'd be maintaining the tank around 1.003-1.005, and seeing what happens. If the fish stop eating or get ill, upping the salinity may be required.>
Well, thank you for your time, and have a wonderful day with your fishes!
Best Regards, Ben
<And to you! Cheers, Neale.>


Hi again Marco, another concern...    7/3/12
Hey Again, Marco.
<Hey there Alyson.>
Before I start with my newest concern, I'm hoping I'm doing the right thing by responding to your emails rather than creating a new "thread" I don't know if you use the emails to remember my information etc.
<Yep. Well done.>
My big Gymnothorax tile has been acting strangely lately. Nitrates 0 Ammonia 0 PH 7.9 specific gravity 1.013. 
<Sounds good.>
He was on a hunger strike (which I thought it was at the beginning) and I was ok with that, he has been on some of those before. Then a few days ago I was feeding the little eel (which is doing great by the way growing quick and scar tissue fading) and of course I tried to feed my big eel. He would come up to the food and rub his face on it like he was trying to position it to get in his mouth, then would just go back into his cave. As soon as I would close the tank lid and go sit down, he would do his little "begging" thing where he would come half way out of his cave and stare at the top. So I figured I would try again. He did the same thing and again, as soon as I closed the lid and sat down he would "beg". Today he did eat, but he would not eat from the tongs. I have always fed him with the tongs and he hasn't had a problem with it. The only way he will eat now is if I take the tongs, dangle the food in front of his cave and set the food down on the sand right in front of him. After that, he was eating like a champ, but I'm not understanding why he wont take the food from the tongs anymore. I will continue setting the food on the sand in front of him if that's the only way he will eat, but its difficult because my GSP is not afraid of my big eel and will literally go try to take it from him. My big eel actually acts afraid of the GSP which I thought it should be the other way around lol.
<Wait until this moray eel specimen is full grown. They have eaten or severely wounded GSPs in the past.>
Any ideas why he is refusing to feed from the tongs anymore?
<Not hungry enough, yet... and sometimes appetite comes with eating.>
Or have you ever heard of this happening?
<I don't think this is anything to worry about. There are some moray eels that are good eaters and some that are bad eaters, also depending on the activity of the individual. Some are normal most time, but have phases where they don't eat or are picky eaters. I have an eel (yellow G. miliaris) that shows the behaviour you describe quite often for many years. When not fed for a week or otherwise hungry it will come and eat from the tongs, in other cases it will only eat what is left on the ground or nothing at all. Even the big eels like G. favagineus are sometimes like that. G. tile seem to have more appetite when kept in marine water, but even there you can experience hunger strikes or times when they are not very hungry.>
Like always, any advice would be great. Thanks again!
<No problem. Marco.>

Gymnothorax tile... sys., beh.    1/18/12
Hi there
A few days ago I purchased a Gymnothorax tile and had some problems. Luckily you guys at WWM was there to help me and my eel looked great after adjusting my tank.
The pH is currently about 8, I'm adding 1 cup of salt water to the tank every day,
<Meaning what? You do need a specific gravity of about 1.010 at 25 C/77 F; in other words, about half the salinity of normal seawater, or about 15 grammes marine aquarium salt mix per litre of water (about 2 oz per US gallon). What you can't do is estimate salinity with spoons or cups. Get a hydrometer!>
I have caves, plants and rocks in the tank and my eel is eating very well. Yesterday I saw that my eel was just laying next to the plants in my tank. This morning when I checked again noticing that he was still laying on the same place. Again this afternoon I checked and found he was still laying on the same place. It's very hot here, temperatures reaching 38 degrees Celsius, can this cause the tank's water temperature to rise and be the cause for my eel laying on one place?
I checked for parasites and infections, but he looks the normal brown, grayish colour with white, 
yellow spots.
Thank you
<This tank needs to be cooler. Do water changes and/or float sealed tubs of ice in the short term; longer term, move the aquarium somewhere colder, like a basement, or else buy a chiller. Marine fish (and this is a marine fish for all practical purposes) are VERY intolerant of temperature extremes. This tank needs to be at 25 C/77 F, varying no more than a couple degrees either way across the day. Hmm'¦ do read, research:
Cheers, Neale.>

FW Moray eel behaving strangely 9/18/09
To whom in my concern
I've got a FW Moray eel who suddenly started behaving strangely, jerking head, moving head side to side, more active than usual.
<No such thing as a Freshwater Moray Eel. There are only brackish-water Moray Eels that someone is keeping in freshwater for the time being. Do see here:
Gymnothorax tile is the most common species. Invariably they get sick when kept in freshwater for too long, and loss of appetite is one of the most common signs of a problem. Aim for at least a specific gravity of 1.005 at 25 degrees C to start with. That's about 9 grammes of marine salt mix per litre (i.e., as used in marine tanks, not freshwater "tonic" salt). Within 6-12 months, you'll need to up that to around SG 1.010, about 15-16 grammes per litre.>
Once we fed him a mussel and he regurgitated it 3 times before swallowing it. He use to like mussels but refuse to take any now.
<Mussels contain thiaminase, so should be used sparingly, no more than once a week. The rest of the time offer foods without thiaminase, e.g., lancefish, cockles. Do read here:
He seems interested in food but does not want to take any now!
<Move him to brackish water, quickly.
If you have a marine aquarium, he'll do well there, too.>
We would appreciate your help in this matter as we are not sure what this behavior means. Should we be worried?
<Yes, very worried. This is a classic first sign your Moray is stressed.>
Mervyn & Theoni
<Cheers, Neale.>

Gymnothorax tile problems, no info on setup -- 07/19/07 I bought a Gymnothorax tile a little over a month ago and for the most part he stayed hidden and only out when the lights were out he would flee back to hiding when the lights came on. I have had others that acted a certain way before passing on. <Why did they die? Some information on your system would have been helpful.> This one is exhibiting similar behaviour but the red scat does not bother him like it did with the others that passed soon after acting this way (the way fish attack other fish when sick), which seems to indicate he is not in immediate poor health. I hope I am over reacting to what maybe normal but seemingly long acclimating period. He also does not swim to the top to poke his head out of the water which is probably another good sign. Can you tell from the video if the breathing he is showing is normal? <It's slightly elaborated. It can be elaborated during searching for food, too, since the moray needs to increase the water flow through its nostrils that way.> The main concern is his lack of trying to hide like he does not care anymore. <They are more or less nocturnal in nature and after acclimating will keep this schedule until trained otherwise by feeding them during day. The behaviour you observe is unusual. It seems stressed. What is your salinity (specific gravity should be 1.01 or higher? Are your nitrogenous compounds adequate (no ammonia/nitrite and nitrates below 30)? Was copper used in this system? Any metal parts, products not specifically designed for aquaria? Was this animal fed feeder fish in the store for a long time? In general this species is very hardy in brackish and marine water (I know specimens of 10+ years), so loosing one (or more) and the strange behaviour of this one indicate something is wrong with your system or care. Check especially SG and nitrogenous waste.> I have not actually seen him eat, but do not know how long they can survive with out eating. <Several weeks to a few months, but it is likely it wasn't fed adequately since getting into the trade, so that adds to the time it has not eaten proper food. Not eating is another typical sign of stress.> He maybe just out looking for food but has paid no attention to the guppies swimming near him or just decided to make his somewhat new home finally home and swimming out after accepting the change from one location to another. I was considering trying to get some bull minnows from a bait shop to see if he would eat them. I also have a toad fish that bull minnows would be better and more substantial than guppies and ghost shrimp. <I hope this fish is in a separate tank. It can sting and kill the moray.> Can you suggest some other types of live food I may try for the G. tile? <Minnows, just as goldfish generally have too much thiaminase, which can lead to a vitamin deficiency and result in damage of the nerves. Mollies and shrimps are better alternatives. They should not be too large.> Thank you, Richard. <Hope that helps to find out what's wrong with the system. See http://www.wetwebmedia.com/FWSubWebIndex/fwmorayart.htm for an article on them and feel free to write with additional information if further questions arise. Marco.>


Two questions First of all thanks for your last advice and fast response, I will get the pH and nitrite tests. 1) I have a Gymnothorax polyuranodon (freshwater eel) and some times he changes color to a pale one but just happened twice during a month and later he has its original color, is this normal or what could be happening? is eating well, as I see during everyday observation is quite good. <This is normal... seems to have more to do with "mood" than water quality, other external influences... Not necessarily an indication of trouble> 2) I will get a freshwater stingray soon but I can't find written thinks online about injuries caused by the sting and envenomation, what should I do in case of envenomation or being touch by it sting ( accidentally, of course I will take care of this everyday). <Please take a read through the Freshwater Stingray article: http://www.wetwebmedia.com/fwstingrays.htm and Injury piece: http://www.wetwebmedia.com/Wound.htm and we'll be chatting. Bob Fenner> Best regards. Attn. Carlos Gorgon

Moray growth cycles   7/16/06 I was looking for information on moray eel growth. I bought a "freshwater" snowflake eel of the Gymnothorax tile variety that I have placed with my albino moray which due to information I have researched I am assuming it is Echidna rhodochilus. The moray "trademark" of opening and closing its mouth to breathe is not happening with my albino. The snowflake is breathing in such a manner and I was told by the owner where I buy my fish food that he was a very beautiful and healthy moray as I had just bought him from another shop and went to get some food from my favorite shop on my way home and showed them. Does anyone know the growth cycles of morays? <Mmm, yes... there are some very nice/useful graphs/charts of time versus SL (standard length) for many species available on fishbase.org> I know they are born in one form called leptocephalus and around 3 yrs. change into elvers. Are there species of moray that do not breath the same way or do they eventually over time grow and change into breathing this way? <Mmm, some "gasp" more than others in general...> They are both approximately the same length except the snowflake is flat on the sides with fins to the tail while the albino is more or less round behind the neck with a tail that comes to a point with no fins which seems closest to the pics I have seen of the Echidna rhodochilus of the various morays I have so far researched. <Mmm: http://fishbase.sinica.edu.tw/Summary/speciesSummary.php?ID=11709&genusname=Echidna&speciesname=rhodochilus unfortunately this is one of the species that does not have "Growth" data on FishBase... Rats! Neither is there such presented for G. tile... These are typically slow growers in the wild and captive conditions (actually, likely less than one percent live a year... due to unstable, unsuitable environment mostly). Bob Fenner>

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