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FAQs on Spiny Fire Eels

Related Articles: Spiny Eels The truth about spiny eels; A closer look at these popular but problematic oddballs by Neale Monks, Husbandry of the Barred Spiny Eel, Macrognathus panacalus by Marco Lichtenberger, 

Related FAQs: Spiny Eel Identification, Spiny Eel Behavior, Spiny Eel Compatibility, Spiny Eel Selection, Spiny Eel Systems, Spiny Eel Feeding, Spiny Eel Disease, Spiny Eel Reproduction,

Fire eel frustrations !!  Fdg.       11/19/14
I have a fire eel that has been super healthy and active always. We have had him just under two years in which he has grown from 4" to about 16" and gained much in the way of girth.
Here is the issue.. I can not get the bugger to eat anything but frozen blood worms and live blackworms (I raise myself) I have tried withholding food for nearly two weeks, more than once, and I routinely offer prawn, night crawler, tilapia, krill, meal worms, snails and mysis shrimp. Eaten with gusto by his Ropefish and Bichir and Ctenopoma tank mates but never by him. He comes up to my hand and as soon as he sees it isn't bloodworms he goes in his cave and pouts.
Any suggestions? I am very concerned about his dietary needs. Any advice would be appreciated!
<I'd be worried too! Clearly he's okay if 2 years old, so there's no immediate worry. But do try live river shrimps, as most Fire Eels seem to love these. Earthworms should also be taken. Starving a healthy predatory fish like this for more than 2 weeks isn't a big deal, so feel free to do so. Also try soaking alternate foods in a defrosted cube of bloodworms.
Particularly earthworms as these are ideal, nutrient-rich foods for these fish. Sometimes chopping the earthworms into small bits helps if whole ones are too wriggly.
Good luck, Neale.>

Fire eel  - 01/12/2013
<Hi, Michele!  Sabrina with you today.>
I have a 29 gal 30"long tank with two Glo Fish and one Gourami. 
<The Glo-Fish, actually a genetically modified zebra Danio, are schooling fish and would really like to have more Glo-Fish buddies.>
Three weeks ago I added a fire eel. 
<Oh....  A very interesting animal, but they get a bit too big for a 29g tank....>
The store knew I had a 29 gal tank and gravel bottom but sold it to me. 
About one week after having the eel I decided to read up on them
<Please learn from this experience - the next time you find a potential new fishy pal, no matter how awesome, take some time to read up on them prior to purchasing them.  It may save you some heartache.>
only to find that I should not have a gravel bottom and that my tank size seems to be too small. 
<Yes.  This fish really needs a soft, fine substrate....  and will outgrow this tank.  Worse, when they find themselves in spaces that they don't like, they decide to exit the aquarium and turn into fish jerky on the floor.  It is VERY hard to keep them inside an aquarium, so make certain you have NO holes in the lid, anywhere, and that the lid cannot be pushed open easily from the inside.>
Now I need to make a decision on whether I should be keeping this eel in this size tank. 
<I, personally, wouldn't, unless the animal is still quite small and you can/will upgrade tank size.  The gravel substrate is the biggest hurdle, though.>
I have called the store I bought him from and they seem to feel the tank is fine and say that the fish will adapt to the small tank. 
<I think it's fair to say that I disagree with this.  Vehemently.  No fish will "adapt" to a tank which is too small.  Will it survive?  Maybe.  But is it fair?  Reasonable?  Conscientious?  In my opinion, definitely not. 
Once again, if the animal is still small, and you can/will upgrade tank size, then I think you're okay - for a time.  But not when it gets big. 
And it WILL get big.  Longer even than your current tank.  Your tank is 30 inches long, right?  Mastacembelus erythrotaenia gets about 40 inches long.
 Envision what size space an animal 40 inches long will find appropriate. 
I've seen some videos on YouTube of very large fire eels....  They are very, very large....  It might be worth your while to look these fish up on YouTube and see some of these videos yourself, to understand truly what your animal is and will become.>
My question to you is this inhumane to keep him, I am very strongly thinking on giving him back to the store.
<I, personally, feel that it would be "wrong" to keep a fire eel in a 29g tank, except as a very temporary home while it is a baby.>
I also know that if I decide to keep him that I would have to change the gravel to sand and from what I hear that can cause some problems with the tank with the cycling and I risk the fish getting ick. 
<You won't risk the fish getting ick, Ichthyophtherius multifiliis, by changing your substrate.  This is a parasite that has to come from a fish introduction.  Although you might experience interruption in the cycle, you can combat this with frequent water changes, or by only changing out one half of the substrate, waiting a few weeks, and changing the other half.>
Also I bought two Pictus Catfish from this same store and put them in a 10 gal tank by themselves but they seem to be bouncing off the walls.  Again is this tank not the right size for them?
<Very correct.  This active catfish needs a larger space than 10 gallons. 
It might be worthwhile to see if there are other, more conscientious shops near you that might be a little more thoughtful about the lives of the fish that they're selling.  But regardless, next time you find a fish you want, please read up on them first.>
Thank you very much for your time.  This means a lot to my son and I.
<Thank you for your kind words, and for sharing the world of fish with your son.  He is sure to learn much about the world around him!>
<Best wishes to you and your fish (and your son!),  -Sabrina>
Re... comp. Fire eel & Pictus Catfish - 01/27/2013

Thank you Sabrina for all the information. 
<Glad to help, Michele.>
I have decided to upgrade my tank to 75 gal so I can keep the eel. 
<Do please be aware that even a 75g tank will ultimately be a temporary home for this very large Mastacembelid.  Do take a look about via Google searches, or maybe on YouTube, for images and video of fire eels as adults.
 They're impressive animals!  Hopefully the 75 will suffice for a time.>
I am feeding him, along with the two Glo fish and gourami frozen blood worms every other day (1/2 cube of the Hikari Bro Pure). 
<This is a good food, but the Glo-fish (zebra danios) and gourami both will want/need some greater variety.  I like Spectrum pellet foods for their great nutritional content, but there are many options.  The fire eel may be harder to convince to eat other foods, but I have known them to take live "red worms", very small earthworms that you can get from bait shops.  He may also take other frozen meaty foods.  If he will accept a high quality pellet like Spectrum, all the better, but I doubt that he will.  Worth a try, though!>
Again this was told to me from the store I bought him from.  But I have been asking around and I hear that I should be feeding them every day. 
What is your advice on feeding quantity and how often?
<Daily is okay, especially for the danios and gourami.  But do get some variety into that diet.>
Thanks again,
<Best wishes always,  -Sabrina> 

Fire eel swollen and floating     – 11/20/12
Hi my name is Brenden. I have had my fire eel for about half a year now and I have never had any problems with him before. But just the other day I noticed that he was not eating. At first I was like ok maybe he's just not hungry. But then last night I noticed that he was not able to swim normal and had not control of where he was swimming. Due to this fact I took him out of the tank because I did not want him getting stuck to the filter or causing any more harm to himself but running into rocks or driftwood. I put him into a container that was ok size and I could fit a small heater in it.
I used the water from the main tank to fill it up so it would not stress him out. But getting to the point he's not moving very much anymore, there is swelling in his stomach area, he's floating, and he's losing his color.
I've have been keeping fish for about 8 years now, and this is the first time I have ran into a problem with eels that I'm not sure about. I don't know whats causing this but I may have a clue/guess.  What I think is happening is that he is having problems digesting food, which is causing the swelling or bump on him and also causing air to build up there. The only other thing i can think of that may has caused this is that my old heater was not working right, causing it to heat the tank to much and then not heating it enough, so i had to replace it, but i was not a huge change and i saw it fast enough to fix the problem, i think.  I just hope that you had give me some help/information about what may be going on and how to fix it, if its not too late.    Stuff about my tank: 60 gallons, have a nice fine sand in it, I normally keep the temperature at about 81-82 degrees Fahrenheit, I try to do water changes about twice a month or once every 2 weeks if i have the time, I took a water sample into PetSmart and the results were Ammonia:0  Nitrite:0  Nitrate: 20-40 mg/L  pH: 7.8  Alkalinity:120
mg/L  Hardness: 150 mg/L  Chlorine And Chloramine: 0   So everything is where it should be/ within the normal range    I also do add aquarium salt when doing water changes, i normally add it every other water change  Also when I went to PetSmart the lady there, I know I can trust her because I've knew her for awhile and she also keeps fire eels, said that it could be the digesting problem or maybe due to the temperature change and she told me about how people use small amount of Epsom salt to help with fish digestive problems so i added a small amount of that to the container.    If there is any of stuff that you need to know just ask me.   Also I'm going to add some pictures of my eel to show you what I'm talking about. Never mind, In the pictures I was going to show you, its too hard to see the swelling/bump.   
 Also I almost forgot that he is  also having seizure like things every now and then. I hope you can help me out and
thanks for your time.
<I'm not optimistic, but do try adding Epsom salt at 1-3 teaspoons per 5 gallons/20 litres, raising the temperature to 28-30 degrees C/82-86 F, and treating with a reliable antibacterial or antibiotic medication (ideally, a combination like Maracyn 1 and Maracyn 2 that covers both gram-positive and gram-negative bacteria for best possible chances of success). Spiny Eels are very sensitive to bacterial infections, which are often started through physical damage caused by gravel or sharp rocks. The Epsom salt will act as a laxative and muscle relaxant, both of which can help deal with some types of swelling. Generally, aim to use aquarium salt (sodium chloride) in Spiny Eel tanks at around 1-2 gram/litre, even for freshwater species like yours.
Hope this helps, Neale.>

Fire Eel Feeding - 10/25/2012
Dear WWM,
<Hello, David.  Sabrina with you tonight.>
I bought a fire eel about 3 weeks ago.  It looked a little thin, about 8" long but otherwise was healthy and is now in a community tank with a 5"
tire-track eel and a few angelfish and other fish.  The fire eel hid for a few days then started to come out at feeding time, hanging about at the surface with the other eel at feeding time.  The tire-track eel eats any and every worm that it can get.  The new fire eel is clearly hungry and interested in the worms and tries to eat them but usually ends up spitting out even the smallest ones (or pieces of them) which usually get eaten by the other fish.  It almost looks like it can't swallow them (although it has eaten a few).  I'm thinking of: first, trying frozen food; or second, moving it into a small tank by itself for a few weeks to get it used to eating worms without competition and to fatten it up a bit. 
<I would actually do both of these things simultaneously.  If he was already "a little thin" when you got him three weeks ago, he's probably urgently in need of food by now, and needs some time without any food competition to get used to what and how you feed.  This is one of the less appreciated bonuses of quarantining new fish - getting it nice and fat and happy, used to your schedule and feeding regimen, before having to meet the rest of the tank and compete for food.  Quarantine: It's not just about disease any more!>
I'm concerned because I've never had problems getting spiny eels to take earthworms in the past.
<While you have him in a separate tank (you said "a small tank" - don't go too small, you don't want him to feel like he must escape and become eel jerky for you to find one morning), try a variety of foods.  You'll probably have best luck with frozen bloodworms.  Frozen Mysis shrimp would be a very worthwhile food (Piscine Energetics is my favorite brand by far).
 Try the earthworms again as he begins to get used to feeding time; make sure they're of an appropriate size for him.  Small "red worms", like little 3"-4" earthworms, would be good, I'd think.  Stay away from Tubificid worms; although Mastacembelids do eat them readily, it's just
not worth the significant disease risk that they can pose.>
Thoughts appreciated and thanks in advance,
<Get him off in a tank by himself to get used to the new fare, try other food options, and he'll be chowing down in no time.  I hope.  Once he takes food from you greedily, he's ready to re-join the main tank!  You might consider varying the diet of the tire track, too.  Frozen foods like bloodworms and Mysis, if he'll take them, will add to his diet very well. 
Although small worms (and large worms, when they get bigger) are a great food for spiny eels, most critters benefit from getting their nutrition from multiple sources.>
<Best wishes to you,  -Sabrina>
Fire Eel Feeding - II - 10/29/2012

Hi Sabrina,
Many thanks for your quick reply.  I tried frozen bloodworms - both eels acted like I was trying to poison them
<Surprising!  Do try frozen Mysis, other options....  and keep at it with the earthworms.>
(other fish were happy though!).  The fire eel took a couple of pieces of earthworm this evening so I'll wait for a couple of days before moving it into its own tank - it's really trying, and the other thing is that there's a good chance we'll lose power in the next few days (eastern coast US) and I don't want to create too much disruption.
<Ahh, wise.  Best of luck - keep safe, okay?>
<Best wishes,  -Sabrina>

fire eel seizure  10/31/11
Hi I have had a fire eel for 2 years now we have had a few other fish they did not survive I think we had to many the tank has only had her ( or so we call her Jeanie or Houdini ) for 3 months now water changes and all she only eats red worms from a fish store today she seized started twitch and seizing lost all her color and seemed dead I held her in the water and kept stroking her side about 14 minutes later she seemed to be coming out of it gaining color back her eyes are still cloudy for about 20 minutes she
stumble around like drunk now she seems aware of everything and swimming but not totally herself. what is going on please help Greg we just bought new worms yesterday temp is 82
<Very strange... and frightening. I would label this behavior as you have... some sort of seizure. Other than the usual "good husbandry", perhaps expanding the diet or simply supplementing it w/ the soaking in
vitamin/HUFA preparation ahead of offering, I don't know what further you could do. Have you read on WWM re Mastacembelids? Start here:
and the linked files above. Does anything in your reading "jump out" for you? Bob Fenner>
Re: fire eel seizure 11/1/11

Thank you so much Bob for replying the site was very informative happy to say I put salt in the tank last night 35 gallon tank sea salt trying to be safe about 3 tablespoons and put her old tube back in that is the only thing I can think of that has change there is wood in the bottom but not enough for her to completely hide I read on your site I believe that light can cause erratic behavior and the tank was recently put in front of a window maybe that caused it?
<May be... but I suspect something else... Perhaps the wood rotting/decomposing a bit has changed some aspect of water quality. I will say that 35 gallons is small for a larger species, specimen of spiny eel, and that they can be very sensitive to accumulation of metabolites. Best to super size their systems, have redundant filtration and be VERY regular re water changes and other maintenance>
today she came out of her tube and ate like nothing had ever happened skimming the surface and nosing us for food she is a strange one I hope her tube back in will stop what happened. what else could we offer her aside from worms she is around 9" or so.
<See where you were referred to... the FAQs, feeding...>
I will be stopping at store tomorrow to test water and pick up vitamins we tried moving her over to frozen shrimp and she refused along with the other worm places is it common for them to be picky? Greg P.S you guys are awesome
<Welcome. BobF>

Question About Fire Eel Diet   3/21/11
Hello, I bought a 10" Fire Eel on Tuesday. (Today is Sunday.) Until yesterday, I tried feeding her frozen bloodworms in a cube but she paid no heed to them. Today I went and bought freeze-dried krill. After holding the piece of krill in front of her for fifteen minutes, she finally lunged forward and ate the krill. She munched on it for a few seconds, then spat it out, then ate it again, then spat it out again. After about twenty tries, she gave up and left the krill. What should I do? And any suggestions on hand-feeding?
<Try using earthworms. Fire Eels love them. Set up a composter if you don't have a clean (no pesticides!) garden to collect them from. Bait shops may sell them too. Once settled -- which can take a couple of weeks -- Fire Eels do well on a diet of earthworms, strips of thiaminase-free seafood (tilapia fillet, cockles), and live river shrimp. They will usually eat prawns too, but these contain thiaminase, so use sparingly. Wet-frozen bloodworms and krill are taken as well. Don't waste your time with freeze-dried foods. Do review tank conditions, e.g., no other bottom feeders should be kept with them, and the substrate MUST be smooth sand or fine, smooth gravel. Fire Eels are among those species that aquarists regularly kill; they are very, very demanding and not for beginners. Do read:
Cheers, Neale.>

Fire eel compatibility 2/3/11
I have a 90 gallon tank with 10 tiger barbs and 9 glass barbs in it. The tank has been set up since last November, and it was properly cycled, it has two filters on it, an Eheim 2217 and a Marineland Penguin 350B,
<Any filter like a hang-on-the-back filter that demands an opening at the back of the tank WILL allow the Fire Eel to escape. Stick with internal or external canister filters, and plug up all holes in the hood with filter
wool, plastic mesh or similar.>
water parameters normal, ammonia 0, nitrite 0, etc. I was wondering if a fire eel would be compatible with the barbs I have in there already,
or if the barbs would get eaten as soon as the eel gets big enough.
<Yes. Plus, if the Fire Eel is small, the barbs may nip at it, and once Fire Eels get damaged, secondary infections usually follow on.>
My local pet store's fish guy said a fire eel would be fine with barbs, and they should be getting some eels in tomorrow. Will a fire eel leave barbs alone? I have researched this and gotten mixed results. What's your opinion on this?
<Hope this clears things up for you. Do have a read here:
Spiny Eels are usually killed by their owners one way or another. Review aquarium security, substrate, tankmates, diet, and water chemistry before purchase. Cheers, Neale.>

add Figure 8 Puffer to tank? 11/10/10
Hi, Crew,
I have a 90 gallon low-end brackish tank, sg fluctuates between 1.003 and 1.005. I inherited a disparate group of fish about a year ago that I've been trying to accommodate. In this particular tank, I have one archer (Toxotes jaculatrix), a tire track eel and a fire eel. The eels are both 8" long. The eels seem to tolerate the salinity--do you think this will be OK long-term? Conversely, do you think the archer will be happy in this level of salinity? The archer seems very happy at the moment (it's probably about 1 year old). I realize I'm compromising a bit from either side of the salinity scale with these fish. Next, I have a scourge of Malaysian trumpet snails in this tank. I am toying with getting a figure 8 puffer for the tank because 1) I love puffers and I understand figure 8's are low-end brackish and less aggressive than other puffers; 2) I don't see much in the tank at any given moment except for the archer because the eels hide; 3) I would like to control the snail population.
Is this a bad idea?
Thanks for your help in advance. I appreciate your time.
<Hello Laura. Tyre-track Eels will certainly do okay at up to SG 1.005 at 25 C, but Fire Eels I'm less certain on, and I'd tend to nudge the salinity down to about 1.003 at 25 C. The Archer shouldn't mind, and that'll still be salty enough for a wide range of species, both true brackish water fish and salt-tolerant freshwater fish such as Brown Hoplo Catfish, Horseface Loaches and virtually all of the livebearers. Now, as for Figure-8 puffers, while this might work, I think you'll be disappointed at the impact they'll have on Melanoides snails. You'd be much better off with Assassin Snails, Clea helena, which should acclimate to SG 1.003 without problems given they're members of a marine snail family, though I've never tried it
myself. They're cheap enough that trying them out won't be expensive. Allow 3-4 Assassin Snails per 10 gallons if you want them to exist in sufficient strength to depress Melanoides snail numbers. The thing with puffers in general is that they won't eat snails if softer, easier food is on offer -- and that can sometimes mean the fins of other fish. Plus, the small size of Figure-8 puffers makes them easy prey for adult Archer Fish, Tyre-track Eels and Fire Eels. Obviously an adult Fire Eel will need a tank bigger tan ninety gallons, so you may be planning to rehome him as/when he gets above a certain size. But an adult Archer fish could swallow a Figure-8 puffer in one gulp! Do not underestimate how predatory Archer fish -- sure, they enjoy eating insects, but they are dedicated fish-eaters as well. Finally, do understand that Melanoides snails are not in themselves harmful, but they are indicators of aquarium conditions rich in organic matter. It may well be that your tank is less clean than you think, and you're overfeeding your fish far more than you suppose, and if you have a lot of algae, then adding fast-growing plant species might make a difference. Treat snails as a symptom, not a problem, and it's much easier to effect a long term
solution. Cheers, Neale.>
Re: add Figure 8 Puffer to tank? 11/10/10

Thanks, Neale!
I sure wasn't thinking about the Archer going after the Puffer, so thanks for that! (I actually saw the Archer eat one of the snails the other day, but I figured that was an anomaly.)
I'll check out Assassin Snails. Luckily I don't have algae in this tank, but I am trying to find the right amount of food/feeding times for the eels.
I've probably been overfeeding the eels. They seem so temperamental and unpredictable. I understand they shouldn't eat every day and will sometimes go for a couple of weeks without eating, but this makes me nervous! I don't want them to starve. I probably just need to calm down about it!
By the way, I searched but couldn't find how long it takes for a fire eel to reach full size--do you know?
Thanks again,
<Hello Laura. Fire Eels growth rate varies with age, but specimens under a year old can add about an inch in length per month. Growth slows down a bit after that, but you can expect yours to be at least a couple of feet long within 18 months, and nearer three feet by the end of the second year. If the Fire Eel was stunted for whatever reason while it was younger, it will grow quite slowly, and may never reach its full size, fish growth rate being determined by age, not the need to reach a certain size. This is why some people find their Fire Eels get really big, really fast while others find their Fire Eels quite slow growing fish. A bigger problem will be aggression: all the Mastacembelus species are territorial, and Fire Eels and Tyre-track Eels are unlikely to coexist in a relatively small tank, Fire Eels in particular being notoriously grumpy fish. Look out for unusual white marks on their bodies indicative of fighting. Sometimes juveniles get along well, even sharing caves, but do be aware than this situation may not persist. When feeding predators, the "art" is providing enough that their bellies are gently rounded, but not obviously swollen; if the latter is the case, you fed too much in one sitting! Earthworms are the best food for Spiny Eels, but they sometimes escape into the sand, and when they die there, you'll get lots of nitrate and phosphate in the water you don't want, as well as food for Melanoides snails. Best to feed little but often, rather than gorging the fish a few times per week. Cheers, Neale.>
Re: add Figure 8 Puffer to tank?  11/11/10

Thanks, Neale, this is very helpful indeed. I think I may start looking to re-home the fire eel now.
<Glad to help. Cheers, Neale.>

new Fire eel, Neale's go  10/25/10
Hey guys, I just got in a new 7inch fire eel and it looks ok, but I noticed that while it was in the fish store they had it in gravel and any time I would go look at it b 4 taking it home it would be buried in their regular size round gravel. In my tank I've got white and back sand, and sum plants and stuff for him to hide and feel more comfortable. my question is, is there a reason he is not burying himself in the sand but keep chilling at the top of the water in the plants? I've read that ppl talk about this but they say their eel is on its side or upside down. mine is not its just up there not really doing n e thing. don't get me wrong at night he moves around and stuff. but .. how come no burrowing?!? it that ok or what?
thanks for the help guys at WWM :)
Bless! Brad
<Hello Brad. If you have plants at the top of the tank, especially floating plants, it is very normal for Spiny Eels to tangle themselves up in those plants. In fact spawning seems to take place in floating plants. So if your chap otherwise looks healthy, and better yet, is eating, I wouldn't worry about it. Cheers, Neale.>
new Fire eel, BobF's turn
Hey guys, I just got in a new 7inch fire eel and it looks ok, but I noticed that while it was in the fish store they had it in gravel and any time I would go look at it b 4
<Please, no "net speak">
taking it home it would be buried in their regular size round gravel.
<... please read here:
and the linked files above re Mastacembelids>
A/the choice of substrates with spiny eels is crucially important>
In my tank I've got white and back sand, and sum plants and stuff for him to hide and feel more comfortable. my question is, is there a reason he is not burying himself in the sand but keep chilling at the top of the water in the plants?
<Likely this gravel is too coarse, sharp... painful to its skin>
I've read that ppl talk about this but they say their eel is on its side or upside down. mine is not its just up there not really doing n e thing. don't get me wrong at night he moves around and stuff. but .. how come no
burrowing?!? it that ok or what? thanks for the help guys at WWM :)
Bless! ..Brad
<Brad, in future, please run your missals through a spelling/grammar checking ahead of sending.
Bob Fenner>
Re: Sick Eel with White Patches

Thanks, unfortunately the eel did not recover and had to be removed.
<Sorry to hear this.>
This was an extremely fast-moving infection, especially for such a large fish (3'). From zero symptoms to dead in 3-4 days.
<Indeed, very fast.>
Nitrates were tested at 30 or less (per color scale) every month or so, but it is a 400 gallon tank with only 3 fish and 2 (now 1) eels so the biological load is light. Has about 250 lbs of live rock in the main tank and a bioball filtration system in the sump. Water changes 40 gallons every 10 days. I don't have a PH score right now but most likely it is fine given this maintenance.
<Yes, sounds OK.>
Both eels came from LFS about 6 months ago that was trying to get rid of them due to lack of demand. Neither one can be described as aggressive eaters in the sense they will dash out and grab at food, have to put the food on a stick and put it near their mouth before another fish grabs it. So they got plenty food but maybe not the strongest to start. Maybe that is why the LFS was getting rid of them. I will watch the remaining one and continue to monitor tank conditions and consider the hospital tank at the first sign of trouble.
<I'd also add vitamins to its food regularly (at least once a week) to replace anything lost due to freezing and thawing processes. Cheers, Marco.>

Fire Eel Sick  10/21/10
I have a Fire Eel whom I have had for a couple months now.
<Nice fish.>
He just recently started to have these white spots appear on him and is losing the color in his rostrum.
<Oh dear.>
They appear to be discoloration and are not on the outside of his skin. I'm pretty sure that it is not Ich but I'm not sure what it is.
<Fire question. Do you have gravel or sand? Gravel damages the skin of Spiny Eels, and since they use their nose to dig into the substrate, the nose is often the first part of their body to get damaged. Small specimens are particularly at risk, and while large spiny eels -- upwards of 45 cm/18 inches -- might be okay with smooth, fine gravel, I personally would never, ever keep a spiny eel in a tank with gravel. It's just too risky, and the evidence gravel damages them is overwhelming.>
He recently fell on the carpet and was out of the water for a short period of time.
<Exposure to air is in itself not a disaster, provided the fish is quickly returned to the tank.>
I got him back in the aquarium quickly, but right after that is when he started to show signs of an illness.
<Yes, likely damage to the skin. As with gravel, drying can cause damage to the skin, and the longer the fish is exposed to air, the more serious the risk of damage. Spiny eels are incredibly sensitive to this sort of thing, and once the skin is damaged, opportunistic bacterial infections aren't far away.>
The tank is kept at 80 degrees Fahrenheit with a small amount of aquarium salt.
<How much? I'd add at least 2-3 grammes/litre, just as if treating Ick.
This won't stress the other fish, and will be a preemptive strike against Ick.>
Nitrates are at 10 ppm, Nitrites at 0 ppm, hardness is 75 ppm (soft), 0 chlorine, low alkalinity, and 6.8 pH. 45 gallon tank with a 20 gallon sump (I know I will need to get a larger tank once he grows).
<I'll say! These fish are gigantic. Average specimens in aquaria are about 75 cm/30 inches.>
Tankmates include a Featherfin Synodontis and an Ornate Bichir both of which are small.
<Okay. Potentially good tankmates, though I'd tend to favour salt-tolerant species simply because spiny eels do better when salt is used regularly.
Siamese Tigerfish and some of the cichlids make good companions because of this.>
Tank has lots of hiding spots. Feeding the Eel and Bichir earthworms and the Featherfin sinking carnivore tabs. Could the disease be velvet, or something else entirely? If so, what should I do? Thanks in advance.
<Unfortunately, my guess would be a bacterial infection, and I'd treat with an antibiotic. Spiny eels are finicky fish and difficult to maintain if you don't do EVERYTHING right. Do be sure to read everything you can about these fish, and act accordingly. Both Marco L. and myself have kept these fish and written articles about their needs:
Cheers, Neale.>
Re: Fire Eel Sick - 10/21/10

Thanks for the quick reply,
<No problem.>
I have sand in the tank so it shouldn't scratch him when he buries himself.
<The sand is smooth, right? Not sharp? Bear in mind that some sands, for example Tahitian Moon Sand, are abrasive, and these must not be used with Spiny Eels.>
He was only out of the water for thirty seconds max so hopefully his skin didn't dry out to much.
I have put in two tablespoons of salt in the tank already so I will add some more.
<As per dosage.>
What medications would you recommend to treat him with?
<Antibiotics are safe, but otherwise avoid medications where possible, especially copper and formalin.>
Should I start a hospital tank to treat him?
<Would leave him in situ.>
Thanks again.
<Cheers, Neale.>
Re: Fire Eel Sick
Thank you very much!
I have done as you said and will go out to get some antibiotics today. The sand is smooth so it will not hurt him. I deeply appreciate the help.
Best Regards,
<Glad to help Ben. Good luck! Cheers, Neale.>

Fire eel question (Bob, some questions about your Spiny Eel piece)<<Ok>>    10/19/10
Hey Guys,
I was at my LFS and came across some amazing Fire Eels.
<Beautiful fish, though very difficult to keep for a variety of reasons.>
A fish that I had only ever seen in videos on YouTube. I knew right then that I wanted to bring one of them home with me. I've got a 8'x2'x2' tank, crushed coral substrate and smooth black river rocks making caves with 6, 5" Fronts, 2 4" blue dolphins, 1 9" black Arowana and 2 4" Altolamprologus.
<Here's the deal. Hard water isn't a major problem as such, but crushed coral will probably raise the hardness and pH well above the comfort zone for these essentially soft water fish. They really need something in the range 5-20 degrees dH, pH 6-8. Yes, there are spiny eels in both Lakes Malawi and Tanganyika, but not Fire Eels! Any of the Malawian or Tanganyikan species would get along fine with all of these fish, except the Arowana, who has no business being in a hard water community at all, and in
any case, will soon start seeing the smaller fish as food.>
<<And crushed coral is a very poor/unsuitable substrate for keeping Mastacembelids>>
In the research that I've been doing over the weekend I think the Fire Eel would do ok in my tank with the fish I have now.
<Not quite. The tank is big enough, and Fire Eels have certainly been kept with Arowanas, particularly the relatively peaceful South American Arowanas. On the other hand, the water chemistry required by Malawian and Tanganyikan cichlids is far towards the hard/alkaline end of what Arowanas and Southeast Asian spiny eels appreciate. In short, not a textbook combination of species.>
Question 1) will it?
<Does depend on water chemistry, about which you've said nothing. Also, the substrate needs to completely smooth, I'd recommend smooth silica sand, or failing that, very fine, rounded gravel. Crushed coral and/or coral sand is right out. Any rocks need to be smoother than smooth, baby's bottom smooth.
Anything with any sharp or even rough edges is putting your Fire Eel at severe risk of death. The danger is, as I hope you understand, damage to the skin. Once scratched, these fish are astonishingly prone to bacterial infections. They react badly to copper and formalin, and even antibiotics have a poor track record when it comes to treating sick fish. Obviously, this predisposition to disease is another reason why "feeder fish" should never be used, and diet has to be very carefully controlled to include lots of thiaminase-rich foodstuffs. Earthworms are the single best food around for spiny eels.>
the eels at the store are about 6" to 7".
I have a cover on the tank now but are they really that adapt at escaping?
<Yes. If they can escape, they will. DO NOT delude yourself otherwise!>
Those are the basic questions I have, my main concern would be the small white blob spot on the tail of one of the eels. From what I've read it could be Ick, as the eels had just got to the shop a day before, and if so adding salt and increasing the temp in the tank would help kill the bacteria?
<Salt/heat will treat Whitespot just fine. As for bacteria, there is some argument, e.g., in Baensch vol. 1, that maintaining slightly brackish conditions improves the health of Fire Eels and indeed Spiny Eels
generally. I kept my Tyre-Track Eel in brackish water for several years alongside mollies, Rainbowfish and other salt-tolerant tankmates. Baensch recommends 1-2 teaspoons per 2.5 US gallons, or about 6-12 grammes per 10 litres. This is a very low dosage, far below what is officially brackish water and not enough to stress freshwater fish in most cases, but do observe your other fish and see how they react.>
However in one of the articles I found on your site,
Bob Fenner said "Should any of the spiny eels in the system exhibit red areas, particularly near fin origins, or white, blotchy markings, leave all of them. They are likely to be soon dead."
<Bob is on the money here. Fire Eels and spiny eels generally are extremely prone to these bacterial infections, and if the retailer has done stupid things like keeping them in tanks with gravel, or has fed them feeder fish, then all bets are off. You might take a gamble on a healthy specimen alongside one or more sickly ones, but for the best chance, pick a healthy fish from a batch of healthy fish.>
What is this 'white blotchy marking' on the tail?
<It's essentially Finrot, some sort of Pseudomonas or Aeromonas infection of the skin. You're looking for patches of white mucous initially, followed by reddening, dead white skin, cloudiness of the eyes, and then death as the disease progresses.>
is it really that bad,
is there nothing I can do about it
<Antibiotics may help with minor infections, and maintenance in slightly salted water is probably a plus. But once a spiny eel gets really sick, they are notoriously difficult to treat.>
so I can bring one home and nurse it back to health, or should I just stick to admiring these fish on YouTube Videos? Thanks for your help guys! :)
<Do be sure to read everything you can about these fish, and act accordingly. Both Marco L. and myself have kept these fish and written articles about their needs:
The bigger species of Mastacembelus are perhaps less sensitive to substrate type than the smaller Macrognathus, but apart from the rock-dwelling Malawian and Tanganyikan species, all spiny eels should be kept in environments as free from sharp edges and rough surfaces as possible.>
Bless! Brad
<Cheers, Neale.>

Unhappy Fire Eel  7/28/06 Hello,   <Hi Steve, Pufferpunk here> I'm glad I found this site and I hope you can help me.   <I'll certainly try!> I bought a Fire Eel about a week ago.  He is about 8 inches long. He ate very heartily the first 3 days I had him (hand fed frozen krill) but now hasn't eaten for the last 2 days.  He also seems less like a healthy eel.  What I mean by that is that in the beginning, his head was always sticking out of his cave, now he won't stick his head out at all.   <That pointy nose of his is for digging in the substrate for worms.  Try live blackworms to get him interested.  He will also eat bloodworms & eventually large night crawlers. > My ammonia and nitrite are 0 and my nitrate is about 80 ppm.  I know that is too high and will probably begin doing water changes twice a week at least.   <Woah!  No "probably" about that!  I'd do 25% daily (starting today), till they're down <20.  After that, 50% weekly is recommended.  Be sure to clean up any dead plant material & be sure to clean every inch of the substrate, especially under decor.> I also have a problem with my water turning soft, thereby my pH drops.  I have driftwood in the tank because my Plecos need it and I was told this would continue to make the water soft.   <Stick to soft water-loving fish then, like the Plecos & your fire eel.  Angelfish, rams & lots of other neat fish like soft water too.> About every 3 days I add pH stable which raises the water hardness and also the pH as a side effect.  Currently, pH is about 7.2 and KH is about 3.  None of my fish are aggressive so that is not an issue. <Bad idea, adding products like that.  All your doing is causing a constant fluctuation of pH.  VERY stressful on your fish.  Leave the pH alone & keep fish that will thrive in soft water.> Besides rectifying the water quality, how can I get him to eat again?  He still "smells" the food when I try to feed him and he'll also grab a piece or two but then spit it out.  I know he wants to eat but won't.  Also, any suggestions on being able to stabilize my pH and water hardness on a more long term level (as opposed to having to add chemicals every few days)? <All answered above.  Get those nitrates down, try live worms.  I hope you have a HUGE tank, mine grew to 2', before I had to rehome him--tired of replanting my whole tank every morning!  ~PP> Please help, I really don't want to lose this guy. Thanks, Steve

Fire "Eel", Eye Damage - 10/12/05 Hello <Good morning.> I hope you can help me to help my Fire Eel. When we were cleaning the tank 10 days ago, my eel got a fright and decided to have a 100mph swim round the tank!  <Yikes! Hopefully this system is not too small for him to feel secure....> I think he must have hurt himself as I have now noticed that his one eye is totally white (looks blind) and he has a patch above the eye which seems to be getting whiter by the day.  <Definitely a concern.... Probably did scratch/damage himself during his speedy stint about the tank.> He is also off his food, not having eaten for three days (very unusual for him).  <And not a good sign....> I have bought some Potassium Permanganate (Condy's crystals), but don't know if I can use this as he is 'scaleless' and I have been told to be careful of medications as not all are suitable for eels. <You are correct. Do not use this.... Very, very caustic - will more than likely kill the eel, and can be hazardous to deadly even on stronger fish.> Please help. I am worried about my fat boy! <Bob's recommendation (and I agree wholeheartedly) is to add aquarium salt (the stuff marketed for freshwater aquaria, not marine salt), perhaps at one or two tablespoons per ten gallons, possibly also add Maracyn I & II (erythromycin and Minocycline) as a preventative.... and of course, maintain optimal water quality. Try feeding stinky, attractive foods like bloodworms (live if you can get 'em) or even redworms/tiny earthworms you collect yourself from an area uncontaminated by pesticides/herbicides.> Thanks, -Wendy <Wishing you well, -Sabrina>

Fire Eel Issues - 04/05/2006 I have a fire eel (approximately eighteen inches) in a freshwater tank - think he might about 15 years old - not sure.   <Nice!> A couple weeks ago he stopped eating, became lethargic (not sure I spelled that right), <I believe you did.> and appeared to have labored breathing.  I dosed the tank with Maracyn II for five days, <Why?> and then another five days with Maracyn.   <Again, why?  Did you see symptoms of anything aside from the heavy breathing/lethargy?  Did you have reason to suspect a bacterial infection?> I have only used Mardel products on him including Coppersafe and occasionally Maroxy.   <.... should try not to use medications unless you know there's a disease that must be treated....> He has a couple injury sites that have turned white.   <Disturbing.  How did he become injured?  Tankmate squabble?  Escape attempt?> After the second week of antibiotic treatment, he improved, regained his appetite and was swimming like usual.  Last night, he stopped eating again.  I'm not sure what to do this time around.  I/m afraid he might be dying from old age?   <In all honesty, this is possible....> I am doing 20-25% partials every 5-7 days.   <Ammonia, nitrite, nitrate, pH readings?> He has a small area of whitish skin on the side of his face.  Please give me some suggestions. Linda Itoh Hello, I wrote to you a little earlier and I need to add a symptom I just noticed with my fire eel - his stomach is bloated.   <The bloated belly and refusal to eat are troubling....  I would first check (and correct, if necessary) his water quality....  Next, there are a number of things to consider.  First, simple constipation.  Foods high in roughage content may help with this (adult daphnia, adult brine shrimp....).  Secondly, these dropsical symptoms may indicate an internal bacterial infection; if that's the case, there may be little you can do, depending upon what, exactly, is troubling him.  You might consider trying to feed with an antibiotic medicated food, though this will (obviously) be difficult if the fellow refuses to eat....  Maintaining optimal water quality and hoping for the best with foods to help reduce constipation may be your best first start.> Linda Itoh <My best wishes to your eely friend,  -Sabrina>

Fire Eel Issues - II - 04/22/2006 I have not been doing well with my fire eel. His belly is still bloated and he is not eating.   <Yikes!> I have been doing water testing and the results as of last night were:  ph 7.5, copper .5 to 1.0, <I still don't understand what you are treating with the copper?  Our correspondences haven't let me to believe that you are dealing with ich or other parasites....> nitrite .09, <This should test as zero....  likely you need to do more frequent water changes right now; the copper has destroyed your biological filtration....  And again, why copper?> nitrate (I am still having problems figuring out) I am using tetra test NO3 and color in test-tube matches 25mg on color chart with kit; <Mm, it's in parts per million, no?> however if I divide that by 4.4 I believe  that number is 5.68,  is that good or not?   <You've lost me here; why are you dividing?  Is it not displayed as parts per million, or....?  And what about your ammonia readings?> I think he has an infection and needs to be treated with antibiotics.   <.... this is possible, but not seeing the fish, not having all the data, I really can't tell you what he might need at this point....  If you do suspect an internal bacterial infection, Kanamycin or Nitrofurazone in food is my recommendation....  or at least orally if not in food, if in any way possible.> I have only used Mardel products in the tank.  The white injury sites are from him trying to cram into a castle which is too small for him now which I have not taken out yet because he is so panic stricken when I work in the tank I'm afraid he is going to jump out. <If there is an item in the tank responsible for the injuries to the animal, PLEASE get it out of there IMMEDIATELY.  Replace it with more decor of a more desirable nature, large enough not to damage the poor fellow.  This is imperative; if he's getting wounds from this castle, it needs to go, pronto, in favor of something that won't wound him.> Some years ago I was working in the tank and he took off like a rocket right out of the tank, in the air, and landed on a tile floor.  He did recover but has not been the same since.   <Yeee-ikes!  I can imagine!  Sneaky little fellows....  give him more appropriate hiding spaces, things to make him feel secure, things that won't wound him.> I also have been using well water for the past 3.5 years which I treat with stresscoat when I partial.  Please give me some suggestions?   <This bloating and refusal to eat is hopefully something that can be passed....  I would add a tablespoon or two of Epsom salts (Magnesium Sulfate) per ten gallons of water; this may very well help him pass any blockage.  Secondly, I would absolutely quit with the copper, unless you are treating for ich or some such....  adding copper is shooting yourself in the foot right now, with regards to water quality.  If you are highly confidant of a bacterial infection, I would recommend treating with Kanamycin and/or Nitrofurazone, again, preferably orally and preferably in food.> Right now, I am just doing partials about every 4-5 days.   <You may need to increase this to *daily* with the copper in your tank destroying your biological filtration....  Be testing, *daily*, for ammonia, nitrite, nitrate, pH....> Thank you.  Linda <All the best to you, Linda, and don't get disheartened.  Spiny eels are resilient fellows, and hopefully yours, aged though he is, can pull through this.  Wishing you well,  -Sabrina>

Fire Eel Issues - III - 04/23/2006 Sabrina, thank you for your response with regard to my fire eel.   I had been treating the tank with copper because the injury sites were not healing like they have in the past.   <Copper really isn't very useful for aiding wounds in healing....> I did about a 30-35% water change yesterday and my copper level today is 0.5.  I plan on not adding anymore copper.  I was thinking if I maintain a therapeutic level of copper it would keep him from getting parasites.   <Mm, for the most part, you're not so likely to see parasite issues pop up unless you introduce them; it's bacterial complaints that you need to have concern over.> I have always maintained a level of copper in the tank for as long as I've had him. <With regards for parasite prevention, a more useful and less toxic substance to use is just aquarium salt.  Spiny eels don't much like it, but tolerate it FAR better than copper.> Today my nitrite is 0.3 mg/liter, and NO3 is 50mg/l.  I am using tetra tests with color charts measures reading in mg/l.   <I see.  mg/L is the same as ppm (parts per million).  Thus, you have .3ppm nitrite and 50ppm nitrate.  You most certainly need to do some hefty (or heftier) water changes; spiny eels don't appreciate high nitrates....  I would quickly strive to bring this much lower; 20ppm at a maximum, less if possible.> The only test chart I see with ppm's is the copper chart.  I am thinking I need to another partial today; but I just don't know.   <Yes, absolutely.> My ammonia  is 0 according to the tetra test color chart reading from 0 thru 5.0. <Get the nitrite to zero, and the nitrate down.> Interestingly, after I did the 30-35 partial he actually ate some food last night; <Ah!  Good!> but still looks very uncomfortable, and is still bloated. I thought the bloating was due to a bacterial infection which is why I'm thinking he needs antibiotic.  Can you tell me where I can Kanamycin in the oral form?   <You might have to mix it yourself, or take a look at http://flguppiesplus.safeshopper.com/234/cat234.htm?590 - they have an antibacterial medicated flake with Oxytetracycline, which might also be effective.> The only antibiotic I keep on hand are the Maracyns.   I did not put Epsom salts in the tank yesterday because of the partial and he seemed to have gotten some relief from it.   <The Epsom cannot cause him harm, even if he were in perfect health, and may help *immensely*.> I'm so distraught over the possibility of him not making it through this.   <Get the nitrate down....  Discontinue copper....  Add Epsom....  Maintain impeccable water quality (ammonia and nitrite at ZERO, nitrate less than 20ppm and preferably closer to 5ppm)....  Wait a few days, then begin with antibiotics in food if no improvement is seen.  At least, that's what I would do.> Thank you for your help.  -Linda <All the best to you,  -Sabrina>

Fire Eel Issues - IV - 05/13/2006 Hi Sabrina, <Hi, Linda!> I'm writing again with regard to my bloated fire eel.  He is hanging in there; but he is obviously not comfortable.  I added the Epsom and have discontinued the copper since April 25th no copper.  The copper level is holding at 0.25 ppm, <I continue to urge you to get this to zero.> 0 ammonia, 25 mg/l nitrates, <Really needs to be lower still.> <0.3> nitrites, <Needs to be zero. ph is holding at 8.   <Yikes!> I have read that fire eels like a lower ph so the 8 concerns me.   <Yes, me too, a great deal.> However, at this point I'm so frustrated with what to do, maybe the pH8 is not a significant problem.   <Mm, it is a problem, I think.  Many/most fishes are very tolerant of a wide-ish range of pH, but spiny eels really should not be in a pH this high.  Dangerous.> After our last email conversation he was not eating so I put Maracyn II in the tank for 10 days, he starts eating and swimming around.  He will not eat flake food, shrimp, bloodworms or earthworms.   <Disconcerting that he won't take worms....> He eats shrimp pellets and algae wafers.  Since I stopped the copper his welt-like blisters are getting white-ish and he is scraping along the bottom of the tank.   <Still signs of irritation, perhaps at the nitrite, nitrate, copper, or that very high pH - or something else in the water, even.> I have done partials every 2-4 days, however he seems really stressed after a partial.  I am on well water here and I did a hardness test on it - 14 dGH - and 13 dKH.   <Kinda high, there.> I have always used water right from the well, and am now wondering if I should be using water from the tap which is ran through a softener. The tap water reads 1dgh and 12 dKH. <I would advise against the softened tapwater; this can be even more trouble than it's worth.  The very hard, high pH of the current water, though, is troubling.  I would like to suggest that you try doing a couple of water changes (carefully, and spaced apart in time) with some water from a Reverse Osmosis filtration unit or even store-bought bottled water - I don't know where you are, but many places have water stores where you can fill up a 5g water jug for a buck or so with straight RO water.  Just BE CAUTIOUS of this, as the pH of the purified/bottled water will be much, much lower than the pH of the tank - you do NOT want to lower his pH too quickly.> My aquarium readings as of yesterday are 18dgh and 10 dKH. I had to have my husband help me with these tests. Very complicated for me.   <And very kind of your husband, too - thank him for me.> Seems like he has skin problems since we moved from city water to well water.   <Bingo....> I'm probably just grasping at straws at this stage.   <I very strongly feel that the bulk of this animal's problems are environmental.  I would actually hold of from medicating at all (aside from the Epsom salt, I would use that again after your next water change).  I would like to see this critter VERY slowly (as in, 0.2 a day) go down to below a 7.0 pH with as close to zero nitrate as possible (below 20ppm at the least), zero ammonia, zero nitrite, zero copper, and lower hardness with the use of RO/bottled water.  I really think a more accurate environment may be the whole key here.> I have purchased Maracyn Plus Biospheres Antibacterial (Sulfadimidine and Trimethoprin).  Do you think this would help with the skin welts?<Mm, I would hold off on medicating this animal any more than absolutely necessary at this point and see how an improved environment affects him.> Please give me your thoughts.   <You've got 'em now, and I hope they help some.> Thanks,  -Lyn <All the best to you and your eely buddy,  -Sabrina> Fire Eel Issues - V - 05/15/2006 Hi Sabrina, <Hi, Linda!> I'm writing with an update on my fire eel.   After I read your last reply, I did a small partial - only five gallons of aquarium water - did I replace with store-bought bottled water.  I'd like to explain something to you that my husband explained to me before I give you the numbers.  I have been testing the PH with a tetra test kit that reads from 5,0 thru 10,0 and the aquarium water has been reading an 8,0.  He brought in the ph kit for our pool water that reads in tenths from 7.0 thru 8.0.  We tested the aquarium water (before small partial) to see if it matched my ph of 8.  It did not - it read 7.6.   <A big difference....  I would test this against another aquarium test kit, perhaps at your local store; many/most stores will test your water for you for free.> We did the partial and  the ph on the tetra kit read 7.5 and the pool kit read 7.4.   <This is a difference that could be charted up to human error....  is very close.> This was on May 14th.  Tonight, I just did the ph readings and they are unchanged.  The nitrites and nitrates are also unchanged.  The dGH is still 18 but the kH is down to 8.   <One last time.  Ammonia and Nitrite MUST be ZERO.  Nitrate MUST be as low as possible; below 20ppm at the least, preferably even at or below 5ppm for this sensitive animal.  These things aren't options, but criteria on which your eel's life hinges.  The pH is next in line of importance.> The magnum filter was clogging up pretty good so I changed that tonight.   <Likely a/the "source" of high nitrate in your tank.> My fire eel has stopped eating again - 3rd night in a row - since I stopped the Maracyn II - he has stopped eating.   <This could very well be coincidence, to be quite honest.  These animals can sometimes stop eating once in a while.> I feel like I need to treat him with something especially since he has stopped eating again. <Bob and I and a few other folks were just talking about this tendency in aquarists; a desire to throw a medication at a problem....  This is a very, very unfortunate tendency, and probably kills more organisms than it saves....  Granted, I do not know you or your pet, but I still feel that throwing medication at the fellow's condition when there are KNOWN problems with the water that must be corrected is folly.> What would be in the Maracyn II to make him eat?   <Can actually be coincidence.> I can't determine if he is breathing easier or not since the partial - I don't think so.  IF he starts to look worse and I decide to medicate him, would it be safe to use the Maracyn Plus Biospheres?   <I can't recommend either, to be honest.  Not until the water quality is rectified.  Fixing the water quality is *imperative*.> In your last reply, you had suggested doing a couple of water changes carefully spaced apart. <Mm, as far as spacing them apart, what I'm most concerned about is not decreasing the pH too quickly.> Do you think another water change should be done in the next day or two, or more towards the end of the week?   <I would say NOW, and urgently so, until that nitrate reading is down.> And, I'm thinking another 5 gallons of bottled water and 5-10 gallons well water.  By the way, with regard to CopperSafe - I was reviewing my emails with you guys and noticed the very first one a Bob Fenner replied to and I got the impression he was okay with using CopperSafe.  I was just wondering about the difference of opinion.   <I am actually sitting with him now, he's right next to me....  We've talked, and he does agree that maintaining copper on spiny eels is not a good idea.  They just don't do well with many medications.  If you like, a direct quote from his Mastacembelid article:  "Spiny eels don't respond well to toxic dye and metal medications."  http://www.wetwebmedia.com/FWSubWebIndex/matacembelids.htm .  I do believe he misunderstood that you had intended to use copper as a constant preventative in the water....  I believe, and I feel that he does too, that this is a bad idea.> Thank you for your reply - again.   Lyn <Please do go ahead and read over the article and the FAQs file linked to it, if you would....  hopefully you might find some other piece of insight that would be of help to you.  Wishing you well,  -Sabrina> Fire Eel fdg., sys./comp.   4/1/06 Hi Crew! <Michael> Hope all is well in Wet Web land. I have a feeding issue with my 12" Fire Eel.  I purchased him 8 days ago from my LFS and since then I have not been able to get (him or her) to eat. <Happens... Mastacembelids don't like changes... and being "moved" is a biggie> (We will assume its a he).............  I have tried feeding him frozen bloodworms with no luck and have just tried frozen krill even though I could not find any documentation supporting krill to feed him. <Some will take... but takes training on to> He is in a 94 gallon corner tank with plenty of caves housed with a red empress, Hap Ali, sunshine peacock, yellow lab, pike cichlid, <These are aggressive species...> and 2 cats (4" and not sure the type).  All fish are between 4-5 inches.   I understand that there is some good competition for food for him and have found ways around that.  I have tried using a feeding stick to spear the krill and have used the stick which acts like a turkey baster as well to blow the bloodworms by him.  He has had ample time to eat both.  My latest attempt today was to put the bloodworms in a shot glass and to lay the glass in the tank (and yes, I took the Jack Daniels out of the shot glass first). <Heee, good idea to both> The bloodworms stayed in the glass and the cichlids left the food alone.  I left that in there for a half hour and watch patiently to see him not eat. I have read and re-read your archives and understand that they can go on hunger strikes for weeks at a time but I guess I would really value your input on my situation. Aside from not eating he does look healthy and acts fine. Thank you in advance for your assistance! Michael J. Bukosky <I would try some live worms... likely "black Tubifex" if you could find, or other... placed in a container as you've done here... but really, the best scenario is going to be to place this fish in a less-agonistic setting... completely covered top, with "soft" rounded substrate, diffuse lighting and soft/er, more acidic water than some of the fish you list prefer. I would do this move if this spiny eel does not feed within another week. Bob Fenner>

Earthworms 'N' Eels - 03/07/2006 This is just a note for those eel lovers or those wanting to embrace the eel so to speak.   <.... I might pet one, but hugging is maybe not quite in my plans.> A couple of years ago I bought 4 eels for my hundred gallon aquarium.  Two fire eels and two tire track.  Sadly someone left the lid on the tank askew and I lost one a couple of weeks ago.   <Aww!  So sorry to hear this!> It was about 18 inches long.  I still have three left that are about that size, one is a good 23 inches long.  They share the aquarium with a sun catfish, a drift wood cat, a tiny (but extremely swift) zebra loach, a very fat clown loach which I bought at the same time (he's a good 10 inches long) a spotted perch, a dojo and a pair of spotted catfish that act like they're on crack.  I love my eels but let future eel owners be warned, they'll eat you out of house and home.  They pick at flake food in the morning, ah but at night they go through 3 of the large cubes of frozen blood worms  and whine for more.  I'm thinking that someday in the future I will find just one very enormous eel in that tank, all other fish having become snacks.  Do you know if eels might eat fishing worms?   <Yep.  Especially at that size.  I recommend culturing your own, to be sure they are in good health and nutrition.  Google "vermiculture".  You can start with worms in your own yard, provided you haven't used any pesticides, herbicides, etc.> I'm curious but haven't tried offering any.   <I'm sure they'd love 'em.  Try small worms, not big fat Nightcrawlers.> I was kind of hoping that the larger worms might just fill the tanks up a bit quicker.  Luckily I can say that none of them have had an ailment in the years I've had them. (knock on wood) and I don't want to encourage anything a live food might bring in.   <Agreed.> So if you have any information on earthworms for eels please let me know.  It would be much appreciated.    <I say give it a try - I've seen even smallish (<8" or so) spiny eels take small worms.> Thanks Jo <All the best to you,  -Sabrina>

Fire eel 11/3/05 Dear Robert, I wrote to in July with regard to my 10 year old fire eel (in 90 gallon tank) that I have always treated with the Maracyn and CopperSafe. You recommended I get a copper (ion) test kit to monitor the copper level because Stresscoat (which I use all the time) can remove it over time. I purchased a freshwater kit by Aquarium Pharmaceuticals which reads from 0.25 thru 4.0. My measurement today is .25. Is this a treatment level?  <Yes... tween 0.15 and 0.30 ppm of free cupric ion> My old kit by Aquarium Systems (which I cannot find replacement packets for) read 0.15 thru 0.2 on the chart and it stated that this is a therapeutic treatment if maintained for 10-14 days.  I also would like your opinion on this: my fire eel has these blister like, or more like welts, on his sides. He has had these for sometime - they are not new. It reminds me of a hive like a human would get on their skin. And, he has grown up with a Pleco that appears to have an uncanny affection towards him. It's like their glued together, though I suspect the Pleco is sucking the slime off of him. <May be> Again, this has been going on for years. Your comments, please.  Thank you. Linda I. <I would keep an eye on the Pleco... try to keep it weaned away from the eel... perhaps with algae wafers... offered toward the evening/lights out. Bob Fenner> 

Fire Eels, Cestodes, and Praziquantel - 11/01/2005 Hello Crew! I have a 2 1/2 foot Fire Eel that appears to have tapeworms. He appears very healthy and gregarious in all respects, but periodically he discharges some white, flat, many inches long, substance which appears to cause him some discomfort, resulting in thrashing about the tank to dislodge it. Does not appear to be normal waste or a normal way to evacuate based on the discomfort involved and the color.  <Could indeed be tapeworms.... or other worms.> I have not been able to isolate any of this substance as the rest of his tank mates devour it immediately, <Ugh.> which of course means they also have worms if that is what they are.  <Agreed.> He is fed live worms and I know they can be carriers of tapeworms which has caused my concern. <Good concern.> I know he shouldn't have any medications with copper, and I was also concerned because he is scaleless, or nearly so anyway. Some of his tankmates are also loaches and Botias, so I have to worry about them as well since he is too big to quarantine and they and the rest of his tankmates would probably have to be treated as well, anyway. However, all his tankmates also appear to be quite healthy. What medication or treatment would you recommend? <Praziquantel would be my first choice, followed by Levamisole or Piperazine.... There are a number of products available for aquarium use, one being "Prazi-Pro". Any of these medications (or others for Cestodes) will need to be administered via food, I believe.> Thank you for your time. He is a sweet little fiend, and I don't want the worms to cause him problems in the future. I wasn't able to find anything by performing a search for this item in your website. <Glad to hopefully be of service.> Marcia <Wishing you well, -Sabrina>

Fire eel, copper use 7/22/05 Dear Robert: <Linda> I have had my fire eel about 10 years and he is about 18-19 inches and very well rounded. <How nice... great pets, very intelligent> He is very aggressive and spooks easily and has had several injuries to his body over the years.  Only on one occasion did I almost lose him - my local aquarium shop said it sounded like an infection in his gills - heavy breathing - not eating or swimming.  I treated the tank with Maracyns I and II  and CopperSafe and he recovered.  I have used these products ever since, and having read on your webpage that eels are sensitive to copper I wonder if I should stop. <Mmm, no... just "be careful"... not to over-expose> I recently moved ( and the fire eel) to a new home which is on well water and I regularly treat the water with StressCoat and CopperSafe.  May I have your opinion on this treatment plan.  Thank you. Linda Itoh <Mmm, I would get, use a copper (ion) test kit... and know that StressCoat will remove/precipitate copper. Bob Fenner>

Poorly eel... Ps. Sorry for such a long email,  but I thought I'd tell you as much as I could,,, also forgot to add, All the other fish seem ok... And the eel never seemed to eat anything... I got some maggots from the local fishing shop.. the other fish liked them, and the eel showed more interest in them than bloodworms, or anything else I'd been trying to feed him, and looked as if he was trying to eat one, he made a move towards it, but didn't get it in his mouth,,, so I'm not entirely convinced he's eaten too much since I got him.. (about 3 weeks ago) hope you can help.... Sami <This spiny eel is extremely mal-affected by a bacterial infection... though often termed fungal... A very quick administration of antibiotics to the system (Chloramphenicol if you can get it, Spectrogram (product) if not... at double dose... 250 mg. per five gallons, addition of a teaspoon of aquarium salt per five gallons... in a separate treatment system, attention to water quality while there... offering tubificid worms as food... Might save this specimen, but doubtful at this stage. Bob Fenner>

Fire eel purchase in the GWN >I would like to buy a fire eel but I do not find any store of fish which has some can you help me please >>> What city do you live in? It is hard to find you a store without knowing where you live. Oliver sorry, I'm living in Montréal >> Try Nature Pet Center on Newman in Ville LaSalle, they can likely order it for you if they do not have them, speak to Robert. If not, maybe Big Al's Aquarium Services on Boul. Des Sources. Speak to Daniel. Keep in mind that fire eels will get four feet long... Good Luck, Oliver.

Fire Eels Hello-  I came across a website that had your email address and some information on the fire eel. A friend of mine recently purchased a fire eel and would like to get some more info. Would you happen to know how one goes about determining the sex?? <Not able to do... externally... as far as I'm aware> Also, is it ok to put more than one eel in your aquarium?? <Yes... a docile (though does get large) species toward fishes bigger than mouth-size, including other Mastacembelids. Bob Fenner> She would really appreciate any info you could give on the subject.  Thank you, JB Hampton

Purchasing some spiny eels I was thinking about purchasing some spiny eels from an online store. Is it wise to have a striped peacock, a Zig Zag, and a fire eel all in the same tank? <Not problematical in terms of them getting along, feeding/foods, having different habitats if this is what you mean> Also, the site I was planning on ordering from said that spiny eels eventually needed 29 gallon tanks... but I read about people having to put them in 100 gallon tanks, what's the minimum size I can have for one and does it affect what size of tank I need if I have one of each of the aforementioned spiny eels? <Mmm, at least a hundred for the Fire Eel... gets quite large over time, in good health... the others could live in 29 gallon systems (well-covered!). Please read here: http://www.wetwebmedia.com/FWSubWebIndex/matacembelids.htm and the Related FAQs (linked, in blue, at top)>   I read that the eels will eat crustaceans, so I assume a blue crayfish would be a bad tank mate...  Is it wise to order online?  Or would you suggest going to a local breeder or distributor?  Thanks in advance. <Both sources could work... or be trouble. The spiny eels are quite tough if cared for well, and doomed if not... Seeing them ahead of purchase is definitely a bonus, better start if you can find, order them locally. Bob Fenner>

Black Shark and Fire Eel - Out of the Frying Pan and Into the Fire! Hello, hope you can help me!   <I will indeed try.> I have been looking for quite a while and trying to decide what to purchase for my tank or if I need to buy a larger tank if it is needed!  I am wondering if a black shark 2" long and a fire eel 9" long will be good tank mates? <No, black sharks (Epalzeorhynchos bicolor) are said to be very hostile fish.  I've read many sites saying how their red tailed Black Sharks have really hurt some tank mates.  I would think that it would pester a fire eel.> I know that black sharks are aggressive, but are they to aggressive if they grow together! <They will eventually be mean... their nature won't allow them to be nice forever.  No sense putting an eel through that. Here is a quick bit of info on the black sharks.  http://aquarium.wendellarhoads.com/blshark.shtml They seem to list what had happened to their tankmates.> I have heard and red that balas, red tailed sharks, or rainbows and good possible tank mates,  what about black sharks?   <larger rainbows wouldn't bother an eel at all.  The others you run a risk.> Would a lot of hiding places for the eel make a difference or keeping the black shark well fed make a difference? <It would help, but wouldn't take care of the underlying issue that the fish would be mean to the eel.  I suggest that if you want these two fish, you think about having two separate tanks for them.  Then you can enjoy both without worry.  Good luck -Magnus.> Help Needed!!!  Thanks CHO, IA

Puffers I have one question, but first here is my tank set-up. 20 gallon tank with whisper filter and heater (it always stays at 76.5 degrees) inside are two dwarf puffer and three Buenos Aires tetras. I want to add a fire eel. Can I? What I mean is can I add the eel with out It killing the puffers? <No, I wouldn't add that to the tank, I really think that a fire eel will try to eat the dwarf puffers.  Even if it doesn't eat them, it will surely stress the tiny things out.  I would suggest setting a tank specifically for the eel if you really want to get one.>

Fire eel diet Hello, I have been reading your website for a while, it's wonderfully informational. I purchased a Fire eel a while ago.  She is now about a foot long and is living in an over turned decoration for her own personal cave. Her half of the aquarium is covered in a healthy layer (4") of black moon sand, to not scrap her belly if she ever decides she wants to burrow.  The tank mates are 3 fire red dwarf Gouramis, 2 Opaline Gouramis, and an angel fish.  The eel loves ghost shrimp, can't seem to feed her enough, but my pet stores can't seem to keep up with just my purchases per week. Two Eel questions: (1)   Feeding:  What consists of a good healthy eel diet?  What are all my options? <Many things... ideally natural food items like worms (including earthworms, grubs (larval beetles) like mealworms, ghost/glass shrimp... small bits of cut meats, fish flesh> How can I keep my eel healthy and full but not break the bank? <Culture (not you! the food)... and collection in the wild. Do look into growing night crawlers, meal worms et al.> How much of these options should I feed her? <At a foot in length... maybe every other day, enough food to where the fish appears "full"... not bulging>   Should I stock a smaller aquarium of just shrimp or something for her and feed her daily like the other tank mates or keep her on a feast a week schedule (I understand that's more like what their natural feeding habits are)? <Better to not feed too frequently or too much... (2) Future:  Ideally or acceptably, what size tank should she be in when she is full grown? <This may come as quite a shock... but a few hundred gallons. Take a look on fishbase.org re this Mastacembelid species... It does get quite large eventually. Bob Fenner>

A Very Good Fishy Story (well-adjusted Fire Eel) I have a fire eel, quite a crazy and yet good story, just though I'd share it.  I bought a fire eel the other day in Fort Wayne, IN, from a retailer who had it in an aquarium with green terrors, jack Dempseys, Flowerhorn cichlids, African Synodontis, and an EXTREMELY AGGRESSIVE banded Headstander.  Fort Wayne is about 5 hours from where I live, and due to traffic, it waited 6 hours in a bag for me to get it home.  When I got it home, it acclimated instantly.  I have read stories on your website about them getting diseased easily and those refusing food, but mine is completely disease-free, and ate so much beef heart that his stomach swelled to the size of Chicago.  He is fat and happy, and even likes to come out and lurk around during the day.  Just thought I'd share the story. <Thank you for sending this along. Bob Fenner>

Why does my fire eel have yellow markings? >Hi, >>Hello, Marina tonight. >I have had a fire eel (now about 9") for almost a year.  He was about 4" when we got him. He used to live in a 25 Gallon Eclipse (eel proof) until I bought the new 90 gallon tank back in March. Quick cute story- thought I lost him last winter. Went missing for about 2 months.  Turns out he was living in the hidden compartment eating bloodworms as they got sucked up the tube. No worse for were, but bigger. Didn't suspect a problem until the water level on the filter was way too high. Anyway, he lives with a couple of zigzags, a black ghost, a golden Gourami, 4 pearl Gouramis, 5 red Serpae, and a tiger barb. Normal for the tank is flake, frozen beef heart and frozen bloodworms. The big question. Whenever I see a photo of a fire eel it has red markings. Mine is dull yellow.  Any ideas?  Thanks in advance either way.  Great site! >>I've seen them both ways, and have always assumed that it's just a variance on coloring.  Try this link for some ideas http://www.wetwebmedia.com/FWSubWebIndex/matacembelids.htm >>I hope this helps.  Marina

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