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FAQs on Mastacembelid, Spiny Eel Fishes

Related Articles: Spiny EelsThe 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, By Species: Fire Eels, Peacock Eels, Tire Track Eels, Aethiomastacembelum, Yellow Tail Spiny Eel (Mastacembelus panculus), Macrognathus aral, Zig Zag Eels (Mastacembelus armatus)

A Fire Eel in captivity

Spiny eel questions..can't find answers; incomp. w/ GF... gen. Mastacembelids        2/11/16
Hi I recently set up a 55 gal. Tank...although its said to be bad to keep goldfish and tropical fish in the same tank due to temperature issues my goldfish are almost a year old and have been acclimated mainly to warmer water (since day 1)..we'll see what happens.
<Water temperature is only one factor in mixing GF w/ tropicals... Goldfish need hard, alkaline water conditions and they are unfortunately very often carriers of pathogenic diseases, are aggressive feeders, get quite large and quite "messy" fish>
To the real questions though, about a week ago I purchased 5 new fish. 1 Betta, 2 angels (one black one white), a juvenile aqua blue colored fish with red tipped fins (forgot to write down its name) and a one stripped spiny eel.
<Going to be difficult to feed the Mastacembelid here>

I was hoping to double check with professionals whether or not these new fish will grow big enough to stay out of the eel's belly.
<This species not likely to get very large; actually not to live long enough to be trouble in this setting>
It is tiny (prob between 4-6") so is it true I should be feeding it shrimp pellets for now?
<Won't likely eat these at all... Needs live or other fresh dead, frozen defrosted meaty foods. WILL you read here?:
If so...About how long should he be when I change the food source?
<READ; won't work>
Also I'm told he's nocturnal,
<To an extent; yes>
even though he comes out sometimes during the day and is picking through rocks, how can I be sure he eats?
I turn the lights off at night for now (don't have a moon lamp yet) so he gets his turn to roam around...some nights he's come out..others I don't believe so. Is there anyway to acclimate them more for the day time?
<Yes; by the feeding mostly; providing a "safe" haven (plastic pipe, driftwood... cave)>
And last question is completely unrelated...how do I introduce live rock to the tank when I'm ready to get rid of all (or some of) the plastic stuff. Thanks so much!
-Via ny
<I'd suggest you strongly consider either trading in the Eel and/or Goldfish. These animals will not live together long or well together in the one system. Bob Fenner>
Re: Spiny eel questions..can't find answers      2/12/16

Thank you Bob...so I will be taking the goldfish out and putting them back in their original 20 gal. Tank in about 12.5 seconds. Thankfully someone can finally provide all the correct details ....that being said the lifespan of the other 4 fish will be extended...so the overall safety due to size is still in question
<Ahh; thank you for your quick action! BobF>

Questions Regarding One Striped Spiny Eels    6/21/13
I'm just starting out as a fish keeper and was hoping you could enlighten me on Spiny Eels; more specifically the Macrognathus aral species.  I have been looking for information for this particular eel for several days, but more often than not it seems to be confused with Macrognathus siamensis, the Peacock Eel.
<Really? Macrognathus aral is pretty distinctive.>
I was hoping you could tell me more about Macrognathus aral in general; things like temperament,
<Peaceful but predatory given its size, so choose tankmates accordingly: nothing bite-sized>
social compatibility,
<May be kept alone or in largish groups; twos or threes may squabble.>
and perhaps most importantly, the size they are likely to reach in a home aquarium.
<A fair sizeā€¦ 30-40 cm.>
Will this species of eel live happily in a 55 gallon tank with other fish (roughly 2-3" in size)?
<Yes, provided the tankmates are not bite-sized; deep-bodied barbs and characins would be better than anything long and thin like a minnow.>
Do they possess a large bio-load? 

<Not especially, but like any predator they do consume high-protein food rather than vegetables and algae.>
Also, will LED lighting be too bright for eels in general?
<If the light is bright they'll simply hide away in the caves you will provide for them, or bury themselves in the substrate. Do also be careful they can't jump out.>
If so, what can I  do to reduce the lighting without compromising my plants?
<Use floating plants.>
My aquarium equipment is as follows:
55 gallon planted tank
Sand substrate
Aquaclear 110 and AquaTech 30-60 Filter
Temperature: 78F
pH: 7.7
dGH: 7
Aqueon 48" LED Lighting
Thank you for taking the time to read my questions.  I greatly appreciate any and all advice you can offer me regarding Macrognathus aral (aka One Striped Spiny Eels).
<Most welcome. Cheers, Neale.>
re: Questions Regarding One Striped Spiny Eels    6/21/13

Hello again,
Thank you very much for the information; it's nice to finally have some concise facts to work with!  However, I had a few follow up questions based on your answers regarding Macrognathus aral eels if you don't mind.
<By all means.>
You say they may squabble in groups of two or three; I had planned on getting a male and female eel for the 55g tank.  Will they still have issues (I'm not sure if a male/female dynamic changes anything), or would it be better to just keep one single eel?
<A pair could work well, especially in a biggish tank. Macrognathus are generally quite tolerant compared to Mastacembelus species. But if you have two males, or two males and a single female, then any fish species can become unpredictable.>
I had also hoped to keep Cory catfish (6-8) with these Macrognathus aral, but if the eels grow up to 40cm will I encounter spatial issues with these bottom feeders?  (Note:  I would only introduce the cories after the eels were comfortable and eating well.)
<Macrognathus aral will be fine with Corydoras (except bite-sized ones like Corydoras habrosus). Naturally, you will need to make sure both species can feed well.>
If cories are not an option, would bamboo shrimp be appropriate tank mates?
<Can also work, and with less competition. Atyopsis spp. shrimps enjoy fast-flowing water, which may be tricky if you use a lot of floating plants (which Spiny Eels appreciate) but you may be able to create an aquarium with still and flowing areas by putting filter outlets in the right places.>
I would think that if a 3 inch fish is safe from being eaten by these eels, so would a 3 inch shrimp.
<Indeed. Cherry Shrimp would be dinner though!>
On the other hand, shrimp aren't exactly the luckiest invertebrates when it comes to matters of the food chain.
<You haven't kept Macrobrachium shrimps then! Google them; a few are sold as pets, albeit rarely, the Red Claw Macro for example being a pretty good choice. But the famous ones are giant species like Macrobrachium rosenbergii, which I have seen sold in aquarium shops and these will make a meal out of any aquarium fish they can catch. Lovely animals, but best kept alone!>
Again, I greatly appreciate any information you're willing to offer on this species of eel.  Thank you for your help!
<Most welcome, Neale.>

Zig zag eels, stkg., more   8/1/12
I have just started getting into aquariums about 5 months ago. I am addicted to it now. I have a 15 gallon tank now with some phantom tetras, Kuhli loaches, and a zig zag eel.
<I see.>
I am going to buy a 37 gallon tank soon.
<Good. The Spiny Eel in particular will benefit from the extra space. They aren't easy to keep in the long term. Do read here:
Your species, Mastacembelus armatus, is one of the biggest species and should reach around 60 cm/2 ft in length, if not a little more. Obviously even a 37-gallon tank is a short-term fix, and within a year you should have graduated to something 75 gallons or larger. Do bear in mind Spiny Eels are sensitive; you can't wait to buy the right tank when the fish grows -- you need to buy the right tank before it grows otherwise it'll die. I'm not being overly dramatic here. These fish really are sensitive, and once they get sick, they're almost impossible to treat. The 37-gallon tank should be okay for something like the next 6 months assuming your Spiny Eel is small, and doesn't get bigger than 20 cm/8 inches in that time.>
I will put the eel I've had for about 2 months in this new tank. I am going to buy a black ghost knife which I've read is compatible with the spiny eels.
<Can be, but Black Ghost Knifefish are *even* more sensitive fish.>
I was wondering if I could put a tire track eel with the zig zag eel?
<How big is the aquarium you plan on getting? If we're talking 150 gallons, then sure, you should be able to keep both, provided you understand you need a soft substrate for the Spiny Eel and fast-flowing, very clean water for the Black Ghost. Any aquarium smaller than 150 gallons wouldn't work.>
I really enjoy the eels and would like to add another one but not if they don't get along. I have read mixed reviews and nothing solid to go on.
<See, this is the thing. Lots of people buy Spiny Eels and Black Ghosts, and they keep them (they think "successfully") for a few months or a year.
But then these fish die. They think it died for no reason, but almost always, the fish diet because the aquarium was wrong. Too small,  not enough filtration, and in the case of the Spiny Eel, the wrong substrate (e.g., coarse gravel).>
The local pet store has told me they should be fine as long as i by a tire track eel that is close in size.
<The least of your problems. Mastacembelus armatus is a predatory species, yes, and adults can eat quite large fish --  though as a good fishkeeper you would NEVER use live feeder fish! Likewise, Black Ghosts have the potential to eat small, tetra-sized fish, though they prefer worms and insect larvae. But neither species should view the other as threat.>
If this is a bad ideal i would be willing to try other spiny eels, as long as I keep the zig zag eel. thank you so much
<So long as you have 150+ gallons, it's a fine idea. Neither species is easy to keep though, and I'd recommend you stick with the hobby for a couple years before buying a Black Ghost -- they are extremely delicate fish and easily killed by people who don't understand water quality (including nitrate) and the need for high oxygen levels and under-stocked aquaria, which is why you almost never see adults. Mastacembelus armatus is a little hardier, but easily killed by ignorance, and actually does better in very slightly salty water (around 2 grammes/litre) which would be incompatible with the Black Ghost. But it can be kept in plain freshwater, you just need to understand that the moment the fish gets a bacterial infection, it'll almost certainly die, so you have to make sure it CANNOT scratch itself and is NEVER exposed to non-zero ammonia or nitrite levels.
Make sense? Cheers, Neale.>
Re: zig zag eels  8/1/12

Thank you so much for the response.
<Most welcome.>
I have been doing some research and hope  that you don't think I was just jumping into this. I was told that my zig zag eel would only reach 10 inches.
<Not the ZigZag Spiny Eel (Mastacembelus armatus and Mastacembelus favus).
But there is a second species, Macrognathus panculus, that is less often traded but may be sold under the ZigZag name. It does indeed stay relatively small, around 20 cm/8 inches or so, and if you are REALLY lucky, this is the species you have. But it isn't a common species. Do read here:
That article gives you a pretty good rundown on what these smaller Spiny Eels need.>
That is what was recommended for my tank at the time.  The pet store had tire track, peacocks, fire and zig zag eels. They said the zig zag was the smallest. That has been another thing that i have read online that seems to have different answers.  They are either the biggest or the smallest.  What are the easiest ways to tell it is a zig zag eel?
<Mastacembelus armatus is sandy brown with dark brown markings; Macrognathus panculus is similar in basic colour, bit has smaller markings (more like speckles) and has a very distinctive row of specks, like a dashed line, running along the midline of the flank from gill cover to caudal peduncle.>
Its markings seem pretty obvious and the tail was another indicator (it is not separated like some) which i have read is an indicator of the size being of a bigger spiny eel.
<Don't know what you mean by this.>
I have a small pebble substrate that was recommended for the Kuhli loaches and was told it was perfect for the spiny eels.
<Absolutely not! If by some chance you do have a Macrognathus species such as Macrognathus panculus, it MUST have a soft, silica sand substrate (such as pool filter sand). I cannot stress this point too strongly. Spiny Eels do better with sand. Gravel scratches them, and sooner or later (it's a "when", not an "if") they get a bacterial infection on their skin that is always fatal.>
As of now, i only feed my eel frozen bloodworms
<Will need much more than this. Try finely chopped seafood (tilapia fillet, cockles, occasionally prawns or mussels) and very small earthworms.
Bloodworms aren't a balanced diet, and there's also some risk of introducing disease through them.>
and had read not to feed them feeders cause of harmful bacteria.
However, I will definitely stay away from the black ghost knife.
<Wise. Do also notice in Marco's piece he mentions the use of salt as well. Trust me that prevention is better than cure with Spiny Eels. Adding a little salt needn't cramp your style -- most livebearers and Rainbowfish will tolerate the minimal amount of salt needed (2 grammes marine aquarium salt mix/litre) but if you go up to SG 1.005 and sent the tank up as a brackish system (that's about 9 grammes/litre) then you could instead keep him with all kinds of fun brackish species like Mollies, Knight Gobies, Glassfish, even Violet Gobies if you have the space.>
Now i feel pressure to get a bigger tank asap.
<Ah yes!>
The tank size is somewhat of a problem. I could only probably go up to a 55 gallon.
<Too small for BGKs. They are massive fish when mature, and extremely sensitive to pollutants in the water.>
If a tank this size isn't big enough for a zig zag, is there a spiny eel that would work better?
<As it happens, Macrognathus species are quite sociable, so getting a couple more would help. On the other hand, Mastacembelus species are very territorial when mature, so best not kept in groups unless you have a huge aquarium.>
I have a friend with a 120 gallon tank which his had for 15 years.  If you feel the zig zag eel is going to be harmed in a 55 gallon tank, I will move it to his tank. thank you again.
<Do check which species you have. Send a photo if you want a second opinion. Cheers, Neale.>
Re: zig zag eels   8/1/12

This is very disappointing news.  It seems i have been mislead on a bit of information.
http://animal-world.com/encyclo/fresh/Eels/HalfBandedSpinyEel.php this site is where found some information before I contacted you. The eel pictured in this link is identical to the eel I have.
<Well that's a species called Macrognathus circumcinctus. It's one of the Asian Macrognathus, and as stated before, these are fairly small, gregarious, basically easy to keep and feed, but they do need a soft, sandy substrate.>
The fin is the same, color is about the same.  I am aware the name given is different then what I have given, but as you have probably seen, tyre track, zigzag, and banded eels are being confused with each other.
<If you rely on common names, then yes, confusion will be frequent. Best to stick with Latin names with Spiny Eels.>
I appreciate your complete honesty and all the information you have given me.
The substrate is a shock, cause I asked specifically for one that would harm Kuhli loaches and spiny eels.
<Not an expensive fix, so I'd not worry overmuch. I use smooth silica sand (here in England called "silver sand") from a garden centre, and it costs no more than the gravel.>
When I set my new aquarium up, i will use sand.
<Cool. Just be sure you know what you're shopping for, smooth silica sand.
Not sharp sand (obviously!) or coral sand or any of the fancy sands used in planted tanks. Just plain vanilla smooth silica sand. Feel free to add gravel (up to about 10% of the total substrate) if you want to tone down the colour of the smooth silica sand and give it a more natural look, but plain sand on its own looks great and ages nicely, getting much darker than it looks at first.>
I have looked at feeding my spiny eel earth worms, but was told not to until it reached a bigger size.
<For sure.>
I will probably try to feed them as soon I can.  The brackish water idea has never been referred to me. It is a great idea and I am going to look into it.  Is it safe for Kuhli loaches or should i wait to setup my new tank with brackish water.
<Kuhli Loaches cannot be kept in brackish water. Macrognathus circumcinctus isn't a brackish water species, so I'd not keep that species in brackish conditions anyway. Basically avoid water that's too soft or too hard, and if your tankmates allow, add 1-2 grammes salt/litre of water. Kuhli Loaches won't like that, but if you change the aquarium around, bear this in mind and choose species that will tolerate a little salt. It isn't 100% essential, but it can make a big difference to the ease with which they are cared for.>
Please let me know if the link provided helps clear things up or is just more misleading information.
<It's not a bad article at all, though I'd argue with a few minor things, like using "aggressive" when they mean "predatory", and their water chemistry recommendations are the complete opposite of what's stated as their natural habitat on Fishbase.>
Thanks again Neale.
<Cheers, Neale.>
Re: zig zag eels, comp.    8/1/12

Very last time I bother you. Now that the species is known and I feel more confident.  Could you give me just a bit more advice.  Is a 55 gallon take sufficient for this species of eel
and is it safe to add other smaller species of spiny eels?
<Provided the size difference isn't huge, then yes, various Macrognathus species (but not Mastacembelus) species can be combined. Allow something like 10-15 gallons per specimen, not so much because they're territorial, but so they have enough space to find food. Spiny Eels are extremely easy to starve.>
Recommendations on other fish to add with this species.
<Anything that isn't so small it'd get eaten is a good start. But also leave out anything that feeds from the bottom. You will have a hard time feeding Spiny Eels at the best of times! No loaches, catfish, etc. Your Kuhli Loaches may be small enough to be eaten by the Spiny Eels when they get big enough. Good tankmates would be medium-sized, non-nippy barbs, tetras, Rainbowfish and livebearers (and the last two groups especially if you wish to add salt).>
I know the Kuhli loaches are not good tank mates for spiny eels and I always have had the intention of moving the spiny eel or Macrognathus circumcinctus to a bigger tank.
<Cheers, Neale.>

Re: Fiddler crabs versus peacock eel 10/21/08
Thank you so much for the fast response!
<Most welcome.>
Well I do have a sand/gravel substrate, however the aquarium store had large gravel.
<Hmm... in my opinion, plain smooth silica sand is the way to go, particularly with small (sub-20 cm) specimens.>
And the eel was buried in there when I got it. Do you think it is possible that the eel got the infection at the store?
<Quite possible.>
I watched the eel quite intently and he never buried himself.
<Possibly prefers the hiding places available above the substrate. In any case, they feed by pushing the rostrum (the "trunk" on the nose) into the sand to uproot insect larvae and worms. So even at that level, sand helps.>
He actually spent most of his time swimming near the top of the water.
<They do indeed like swimming among the roots of floating plants. They're great escape artists though, so be warned that they're also apt to jump out, if they can.>
Also do you have any suggestions on what I could do to get my tank better prepared for a peacock eel?
<Do read my article; that's everything I know about them!>
I have three small Cory cats, will they be a problem for the eel?
<Does rather depend on the size of the tank and how much food you put in. Assuming you were generous with the food, these fish might get along just fine. The real problems come with "bullies" like loaches and Plecs that will keep the Spiny Eel away from its dinner. Earthworms are the secret to success with the Mastacembelidae, and they will thrive on these tasty morsels.>
I guess I should let you know that I have a 55 gallon tank with a mostly sand substrate. There is some small white gravel mixed in with the sand.
I have got Platies, swords, mollies, tiger barbs, 2 rainbow fish, paradise fish, the Cory cats, and the crabs. Everybody lives perfectly fine together. I usually put a small amount of aquarium salt in the water. Would this be recommended for an eel?
<I suspect the Fiddlers are on borrowed time. They're amphibious and will spend all their time trying to get out. The vast majority of specimens in freshwater aquaria last but a few months. It's a shame they're sold at all, to be honest. Adding "small amounts of salt" won't really have much effect either way. They won't make any of these animals healthier, but if you want to waste your money on boxes of salt, then go ahead, you aren't doing any harm either.>
<Cheers, Neale.>

Questions about tire-track eels 10/10/08
I have a tire track eel who loves his bloodworms. His tank mates also enjoy those instead of the brine shrimp and other goodies I feed them. Yesterday, I decided that hand feeding the eel would be a better idea and he readily took the frozen cube. What I'm worried about - when I look at him closely, the end of his long nose has what looks like a stinger or curved needle (sort of like a fine thorn) at the end. Can or will it hurt my fingers/hand should he accidentally stab me with it when I hand feed him.
<This will not hurt, its quite soft tissue. I've never been bitten by a larger spiny eel and guess it will not hurt much, either. In contrast to some African members, the Asian spiny eels don't have teeth on their palatines and the vomer is toothless, too.>
I had previously written about tank mate compatibility, asking about your thoughts on adding tiger barbs. The fish I had concerned over eating them didn't really care. The eel ate 5 out of the six over a two day time period. He had never eaten live food, but eating tiger barbs whole and alive were apparently a great meal to him. There is one lone barb who he eyes, but leaves alone. It strikes me as odd that he, or his tank mates, haven't finished the final barb off.
<Yes, they can easily swallow fish of the size of a tiger barb and larger ones once they are grown. Tiger barbs like all minnows and carps are no good food fish for your eel. To fatty and containing a vitamin destroying enzyme. Earthworms are loved by spiny eels in general.>
Is there a way to tell the gender on an eel? I'm just curious on how an eel reproduces.
<Yes, but its difficult. Adult females exhibit a larger protruding anal tube, called urogenital papilla, used to lay eggs. You'll need some experience an a very calm specimen to determine sex this way for sure. Females are generally larger (greater girth) than the males. If you got two adults of equal age next to each other it is possible to tell if they are of opposite sex and who is who. For breeding also see http://www.wetwebmedia.com/ca/volume_4/v4i3/Spiny_Eels/Spiny%20Eels.htm and the FAQs, at least for smaller spiny eels its possible.>
One of my Plecos, who is rather large seems like sucking on the eel once in a while, and the eel lets him. Is this normal?
<Yes, their skin mucous seems to taste well. Too much sucking theoretically can harm the eel, so he needs to have the possibility to bury or hide himself if he wants, too. Also, if you see any sores or discolorations Id separate them.>
Thanks and have a great weekend. Skye.
<Will try, have a great weekend, too. Marco.>

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

General habitat questions re Mastacembelids, Gouramis   7/26/06 Hi from New Zealand. Im planning to purchase 3 striped peacock spiny eels and have been searching the internet for 3 days solid trying to gather information. <Is about, but not easy to find... the Net will be much better... soon> Most sites contradict another one so Im all confused. I plan to have 9 Gouramis in the tank as well and two fake rocks that have lots of hiding places, some fake plants, low watt lights, Eclipse Aquarium Hood, and some walnut gravel as it has very small smooth pebbles. How many gallons will the tank need to hold? <Mmm, the "bigger the better"... at least 200 liters...> What dimensions do you suggest? <More "flat" than tall and narrow... to provide surface area for gaseous exchange, habitat for these types of fishes> Am I on the right track with my plans? I just want to get it right so the critters don't suffer. Thank you in advance. Emily <Please read here: http://wetwebmedia.com/FWSubWebIndex/matacembelids.htm and here: http://wetwebmedia.com/FWSubWebIndex/anabantoids.htm and the linked files above. Bob Fenner>

Hello!  I have an eel-related question. Mastacembelid ID, Sys.  7/9/06 Hello!  I've been frequenting your site for the last little while once I started getting fish and realizing that what the pet stores told me was for the most part completely wrong.  Your site has helped me tremendously with my Fire Eel (who I've had now for almost 3 months and he's doing extremely well :-) ) <Ah, good> but I've noticed there is a general lack of information on the "yellow-tail spiny eel". <Mmm... is sold under a few other common names... Most often as the Zig Zag eel on the U.S. west coast... Old scientific name is Mastacembelus panculus, now Macrognathus panculus: http://fishbase.sinica.edu.tw/Summary/speciesSummary.php?ID=10147&genusname=Macrognathus&speciesname=pancalus> I bought one of those about a month ago (he is also doing well, so whatever breed of eel he is, the care is much the same of that of a Fire eel.) <Yes> and he's grown a lot. <Good... though won't get as large... 9 inches is about maximum>   I got him when he was about 2 inches long.  I've looked at various pictures and he seems to resemble a zig-zag eel? <Ah, yes> Albeit slightly yellower, perhaps.  Anyway, I've included a picture so perhaps someone can tell me what it is, or if I'm completely wrong in my thinking that he is a type of zig-zag.  Thank you for your help, and I look forward to hearing from you! -Becki- <Does appear to be this species to me as well... Can make very interesting, long-lived pets... given initially healthy specimens, good care, consistent maintenance and feeding... As with all spiny eels, do pay particular attention to keeping the top entirely enclosed to prevent them exiting. Bob Fenner>

Some Questions about Spiny Eels - 05/22/06 Hi, <<Hello>> First off your site is very helpful and I have learned much from it. <<Is good to hear>> However I do have a problem that I couldn't find an answer to on Google or your site. <<Okay, let's see if I can help>> Im new to aquariums and about 5 weeks ago I purchased a Striped Peacock Eel. <<Read here and at the links in blue:  http://www.wetwebmedia.com/FWSubWebIndex/matacembelids.htm >> At first he didn't eat much (actually hardly at all) but a couple of weeks back he decided to eat as much as he could get.  I would like to know how many 8-10 mm long pieces of earthworms an eel about 7-8 inches should safely consume each day. <<Hmm...would think at least 3-4 pieces would be fine.  Live Blood and Tubifex worms would be relished as well, and will add some variety to the diet>> Also he is outgrowing his home/cave rather rapidly <<Indeed, can reach a foot in length>> so should I try to find him a new hideout (the gravel is a bit to harsh for burrowing) or attempt to possibly put new finer gravel in his half of the tank (during a partial perhaps?). <<I kept some of these eels a few decades back (did I really just say that?!), quite interesting creatures as I recall.  A fine/soft substrate is best/ideal...along with some plants/hiding places...and subdued lighting>> I want your personal opinion/s as well a reasonable answer/s so that is another cause to actually Email you guys and gals. <<No worries mate...I hope I've been helpful>> Thanks in advance, Matt <<Regards, EricR>>
Some Questions about Spiny Eels II - 05/23/06
Wow thank you very much. <<Quite welcome>> I was feeding him as much as 8 pieces and before I decided enough was enough and he still wanted more lol. <<Yes, can be quite glutinous.  Best to feed smaller portions several times a day>> However I know they like to hide and that they like "soft" substrate, I wanted to know if it would be a good idea to change part or even all of the substrate during a partial water change or add a larger hiding spot. <<Would depend much on your filtration setup...but I think changing out parts of the substrate with partial water changes over the course of a week or so would be safest>> Thanks again, Matt <<Always welcome, EricR>>

Peacock Eel questions... sys., comp.   4/26/06 Hello! I just found your site, and it's great! Anyway, I have a few questions. I currently have a peacock eel and 4 mollies (2 Sailfins, 2 Shortfins) in my aquarium. I have read in some places that Peacock Eels like brackish water, <Mmm, can tolerate some...> and so do mollies, but other places say that the Peacock Eel is completely freshwater. <Many Mastacembelids are brackish... not this one. Please see: http://filaman.ifm-geomar.de/Summary/SpeciesSummary.php?id=50400> Do Peacock Eels benefit from marine salt in their water? <Not much, no> How much salt should I add is this is the case? <A minimum amount...> Also, I have seen a 'Figure 8 Puffer' in my local fish shop, and was also wondering if this species is a suitable tankmate. <... no. Too likely to bite the mollies, spiny eel> I have also heard that they are brackish. <... please see WWM re> Any other information about suitable tankmates for my mollies and my Peacock Eel would be greatly appreciated! Paul <Paul... time to read my friend. Learn to/use the indices, search tool on WWM. Bob Fenner>

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 red worms/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.   <Yeeee-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 ppms 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>

Striped peacock eel info   3/16/06 Dear Robert, I am new to eel care and have some questions regarding eel behavior.  My eel is approximately 6-8 in long (I'm not sure exactly because he doesn't stay still) and appears to be healthy.  I have only had him a few days and he still looks pretty nervous about his new home. <Typical> I have a 55 gallon aquarium with 1TB aquarium salt for every 5 gal.  I am unsure about this but have read they do ok in brackish aquariums. <To an extent, yes> My main question is that could my 6-8 in eel eat a 3.5 in Senegal bichir or 5 in violet goby? <No, could not>   My bichir is terrified of my eel and the violet goby is MIA at the moment.   <The latter may have "jumped out"... look about on the floor... or be hiding.> Also I am unsure he is getting enough to eat I have tried fresh raw fish, cut Nightcrawlers, and shrimp pellets.   I have heard and read that these are all foods accepted by eels but I am nervous anyway.   <Best to offer some live worms, insect larvae that sink...> would a sort of community feeding spot work? <Mmm, could> None of my other fish are terribly voracious and I was thinking of a watering hole type situation.   If you could help to unravel some of this I would appreciate it. Sincerely, Matt Tompkins <I do hope your livestock all settle-in... they should be compatible... that is, "get along" with another. I would not add any more salt than you mention... and would try black worms, Tubificids for your Mastacembelid eel for now. Bob Fenner>

Sores on Aethiomastacembelus elipisfer   3/10/06 I just bought a Aethiomastacembelus elipisfer about a month and a half  ago.   This week I see a sore on its side.  Also, it is not very  active, preferring to "make like grass" in the plants.  I am not sure it has  been eating, but have fed guppies and will continue to do so. do you have  suggestions on treatment for these sores? Thanks Pei <Mmm, yes... from Oliver's input and mine posted on WWM (Please use the Google search tool or read here: http://wetwebmedia.com/FWSubWebIndex/spinyeelfaqs.htm These matters need to be addressed aggressively. 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>

FW Eel  1/16/06 Hi, there! First off, I will begin by thanking whomever is reading/answering this e-mail. I am a relative newcomer to keeping FW eels. I currently own two such specimens. One 7" striped peacock eel, and one 4" zig-zag, or tire track eel. I purchased the tire track eel from Arizona Aquatic Gardens (azgardens.com) whose incompetent 'staff' told me that the zig-zag eel would grow no more than 10" or so. I have found since that my eel may grow to 3', which poses a dire problem to me. < Fire eels, Mastacembelus erythrotaenia, gets big, like three feet long. I have seen them in public aquariums at least that big. But the tire track eels that I am familiar with, Mastacembelus circumcinctus, stay around eight inches or so.> <<There are other "tire track eel" species. RMF>> However, there is an even bigger dilemma I am confronting today: is there such a fish as a dwarf starry night eel (*Caeco**Mastacembelus spp.), *and what size does such a specimen attain? Is it a strictly FW fish? What, pray tell, is the recommended pH and aquarium size of such a specimen? I have tried to Google this one out, and have even gone through the German and French websites, with very little success. I am contemplating the purchase, but I am cautious, as the seller (AAG) states such a specimen will not grow past 6". Is this even possible, in your opinion? Thanks again for answering my question and I bid you good day. George < While diving in Lake Tanganyika a few years ago we saw many eels. Some were only 4 inches long and swam like little seahorses while others were at least a foot long. Look at Caecomastacembelus, Afromastacembelus and Aethiomastacembelum on fishbase.org. These are the three genera of eels from Africa. All that I know of get up to a least a foot and a couple get up to two feet. The Lake Tanganyikan ones require hard alkaline water with the others probably tolerating almost any kind of water. The eel you are looking for may be in these groups.-Chuck>

Capitalization, Spiny "Eels" - 12/06/2005 Hi, my name is Silas. I <Your name, I, beginnings of sentences.... PLEASE capitalize....> have two peacock eels I got from a local PetSmart. Tonight I went to clean my tank and I noticed some little worm like things swimming around. I thought they were parasites but then I thought they could be baby spiny eels. <Highly unlikely that these are baby eels. Also, they are not necessarily parasites. Please search on WWM.... start here: http://www.wetwebmedia.com/FWSubWebIndex/fwinvertfaqs.htm .> I was wondering if they can have babies and how big they are. <I recommend a Google search on "breeding spiny eels" or "breeding peacock eels" for more information on the topic than we have available here.> I don't know what to do, so I e-mailed you. Please try to e-mail back soon. the "things" are really small and look like parasites so please tell me if they can be babies or if they are parasites. <Read, my friend; much to be learned here and elsewhere.... I suspect your worms are "visitors" of a sort, indicating an overabundance of "food"/nutrients in your tank. Wishing you well, -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 Montreal >> 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

Peacock Eel average questions/conflicting answers I just discovered your website and I LOVE IT! I've been a constant freshwater fish fan for years and I have just purchased a peacock eel (Mastacembelus erythrotaenia <<This is a/the Fire... perhaps Macrognathus siamensis ? RMF>) and I was just wondering if there was any way to tell the difference between the sexes. Also I have done as much research as I can and I have found so many conflicting reports it makes me dizzy. I just want to make sure I have the basics right so that he/she can live long and happy. For now he's in a 29 gallon (and in about 4 to 5 months to be moved to a 75 gallon) and the temperature goes from 70 (at night) to 75 (in the day). He is in something the pet store called "red sand" but it isn't red and looks like normal sand. The pH sometimes varies from 7.1 to 7.4. He seems to love the sand and only 5 minutes after releasing him he had found a perfect spot to dig and stick his head out. Some of the websites I visited said that they could eat flakes or pellets, is this true? for now he seems happy just to eat bloodworms that come out of this feeder when they are unfrozen. I was thinking (because I know in general spiny eels like live food) to add 1 male guppy and 2 female guppies so that when they mated he could eat the fry. My brother has a soft shelled turtle that he does this with and it seems to work rather well. In a couple of websites they said it would be ok to put him with a knife fish. My knife fish is very friendly and for the short time I had a sting ray in there (babysitting for a friend who's bacteria had all died after his younger brother poured in a bunch of VERY old fish medicine) the knife fish actually made friends with him and would swim just above him and tickle him with his lower fin. These are a lot of questions but I really want him/her to be happy. (I also like to know whether they are male or female so I can name them). >> Your eel should be called "fire eel" by its common name. The peacock spiny eel is another species, that does not have the red lines on its body. If it is a fire eel, it will get to a very large size, that means over three feet long, and he will need a tank large enough to live as he gets older. They do like live food, especially live earth worms. He should be fine with a knife fish. You may want to make sure that your temperature is more stable, best between 74 and 80 degrees Fahrenheit. Good Luck, Oliver

Feeding peacock eels I just purchased a small peacock eel and was wondering if I was feeding correctly. He/she is about 4-5 inches long and I'm feeding shrimp pellets. I read in the information on spiny eels that they won't bite and chew their food. I don't think my eel's mouth is large enough yet to eat the shrimp pellet whole but I dropped a pellet near him (he's burrowed and sticking his head and part of his body out) earlier and it's gone now. Will they eat the pellets once they've softened? Or do I need to resort to frozen food (I live in a college dorm that allows only fish tanks and I don't have access to a store that sells live food so my method of feeding is rather limited)? <Please read here: http://wetwebmedia.com/FWSubWebIndex/matacembelids.htm > In addition to that, I was wondering what would be the best remedies for the most common infections, like Ick. I'm using a product currently with my other fish called CopperSafe by Mardel (Active ingredient: Chelated Copper Sulfate) in combination with a product called MelaFix (it says it's safe to use with scale-less fish). CopperSafe seems to work really well with my other fish, including a Pictus cat, who came in with Ick. But you mentioned that metallic medications don't work well on eels. What should I look for in an anti-Ick medication when it comes to peacock eels? Should I just dose the tank with non-iodized salt? Sarah <Please read over WWM using the Google search tool there, with these questions, product names... I would not use Melafix for anything, nor copper compounds on Mastacembelids or Pimelodid cats... Read my friend, before purchasing livestock, using toxic chemicals on them. Bob Fenner>

Questions about Peacock Eel Hi folks!  <Howdy Carol> First of all thank you for a very informative website! I am a constant reader, and have learned much by reading your articles and responses to other people's questions. <Welcome> I have my own questions for you now, regarding a Peacock eel. I raise Mystery Snails and my nursery tanks are nearly overflowing.  <These are great animals... when/where raised "properly"... unfortunately, most all the ones that go "through" normal wholesale channels are either DOA or very close to it...> I would like to relocate some snails to my 55 gal tank which houses a 5" peacock eel. Would this be safe? <Should be... small snails might be eaten, but this Mastacembelid does not eat larger snails by and large... however, worms of all kinds are history> I don't want to create a scenario that is going to result in snail carnage. I have some Sterbai Corys (10) in the tank with the eel. The LFS was adamant about Peacock eels being 'very, very gentle' and no problems at all with snails. However, I don't know if I can trust them as we all know that LFS's are renowned for misinformation. <All must by evaluated by you in the final synthesis> I have read on the Web conflicting information about Peacock eels, some say that they are extremely aggressive and will take small fish (like Corys) when they get large enough to do so. <I have never seen this... and have handled hundreds of Peacocks... other spiny eels that get much larger (e.g. erythrotaenia, the Fire) don't even touch armored cats...> I have also read that Peacocks are very gentle and won't eat anything aside from live worms, perhaps the odd bit of fresh shrimp, and/or ghost shrimp. <This is my opinion> Can you please tell me the truth... would such an eel take mystery snails, or bite off their tentacles? My snails range from babies of a few mm long to full sized adults. I have even contemplated another tank just to house the eel, but I've run out of room for more tanks quite some time ago. (I guess I could rearrange the furniture again though...).  Also, how do Peacock eels do when housed with members of their own species? <Very well... are extremely social animals> I was advised to get a second eel to make mine feel more 'at home'.  Thank you so much for any information you can give me! Sincerely, Carol <Thank you for writing. Bob Fenner> 

Trapping Spiny Eels Dear Crew, Would any of you have any experience in trapping eels? I have a 240gal. acrylic tank that I want transfer my Discus and Angels and Clown Loaches to.  In this tank are several Leleupi Cichlids, Dnobnoi and a large clan of Brichardi so I will have to take all the rock and wood out anyway. But, as you know, the eels will be able to go under the gravel.  The gravel is 4 to 5 inches deep and supports a jungle of Giant Val and a variety of other plants I would rather not have to rip up (their roots are a mass of tangles).  Also, there are LOTS of eels.  I had put just two in.  Now,  what are the odds that the 2 eels I bought were male and female!!!  Or are they able to change sex to fit the situation?  At first I was so amazed, and thrilled, to see the cutest little baby, but they just kept coming!  I think there must be at least 5 generations in there.  I think the smallest might be catchable because they don't seem able to get under the gravel and instead live amongst the plants and wood.  However Mom and Pop and several of the teenagers disappear with no trouble at all.  Any suggestions?  Thank you for any help you can offer. < WOW, WOW, WOW. If these are true Lake Tanganyikan eels this is the first incident I have heard of. African eels are very expensive and are not very common in the hobby. Too bad you want to swap them out. Many of these eels sell for up to $45 plus depending on the species and the size. I suspect that they have been breeding in the Val grass and feeding off the numerous baby cichlids being bred in the tank. A few years ago while diving in Lake Tanganyika my wife noticed a pair spawning with cichlids all around eating the eggs. Sorry they are a real pain to catch and I am unaware of any traps available.-Chuck

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>

Ghosts, Knives and something else So how many of each Corys and/or loaches? <Say four to six Corys or three or four loaches. But as I said the loaches will get too big in time. You may have to trade them in at some point. And what are your thoughts on a tire track eel? <A tire track eel will get over 2 feet. Recommend min tank size is over 100 gallons. Don> Nicole

Large FW Catfish fed feeders... I just found out you guys existed! Boy I could have used your help a long time ago. I didn't really have a question for ya, but wanted to tell you a story. I know you hear this a lot but I was also the victim of poor pet store knowledge (more than once) and ended up with a Pseudoplatystoma corruscans (shovelnose catfish). <Cool cat, but very large with a larger mouth> The guy told me at the store that at about 6 inches the little guy was pretty much full grown. <LOL> I know now that that was completely false. Anyway we kept the little fella in our 33 gallon and he is was one of my favorites in the tank. Loved to eat and has really unique patterns. We were planning on keeping him till he got closer to a foot long. Unfortunately he never made it that far, he inherited what I think was a bacterial disease from some feeder comets, <Please, Please, PLEASE! No feeders unless you're willing to QT them. Garden worms and human seafood (shrimp, mussels, etc.) is far safer for these large cats.> even though we wouldn't have had him for very long I was really mad that he died so quickly (3 months). He quit moving around and had his feelers pulled back to his side. A usually quite knowledgeable fish keeper told us to just let it ride for a couple of days, thinking he might just be shedding, <Shedding??? Catfish don't shed there skin>> since he was the only one in the tank that was sick. He died the next morning. The other fish I was misinformed about is our fire eel. He lives in the same 33 gallon tank (don't worry I've treated the tank with Pimafix because whatever the catfish had it affected our leopard leaf fish, he got some body slime and cloudy eye but everyone is healthy now) and looking at your website I found out that he may get 2-4 feet long. The pet store told me he would be max a foot and a half. Right now he is just about a foot long and happily resides under a large piece of driftwood, coming out at night and to eat out of my hand, he loves frozen shrimp!<Great, safe food. But vary it somewhat.> I was wondering how long it will take for him to get too big for the tank and have to be given away. <Not really sure.> I'll miss him but it's not fair to cage him in such a small tank. <True> Will he really get 4 feet in captivity <possible, over 3 for sure.> or could we maybe get away with keeping him in a 100 gallon or more? <Would surely allow you to keep him far longer. Min. recommended size is around 80 gallons. Upgrade your plan to a 125 or 150 and you could have him for life.> Sorry to write you a novel. Pet stores should be forced to have accurately knowledgeable staff, the losers are the poor fish and pissed off purchasers. Don't rush to write me back, Amber <Don>

FW Eel for 20g Tank?  7/26/04 Hello <Hi, Pufferpunk here> I am sorry for sending you this letter but I have looked for days to find out about something.   <You don't have to apologize for asking questions, if you can't find the answer somewhere.> That something would be that I am looking to buy an eel and I only have a 20 gallon tank.  Would that be enough to have a eel.  If so you tell me which one or ones would be good to get.  If not could you tell me of something similar. <Most eels grow fairly large--way too large for the tank you have.  The only smaller eel that comes to mind is a spiny-nosed eel.   http://www.aquariacentral.com/species/db.cgi?db=fresh&uid=default&ID=0603&view_records=1  Even this eel will grow to 6".  Eels will only eat live foods, so be prepared to spend some $$$ on worms & such.>   Thank you Tyler I would really appreciate it if you would write back. Thanks <Good luck finding the eel you want.  ~PP>

Sick eel please help I have a Aethiomastacembelus elipsifer Tanganyika eel and it does not look like he is eating and has gotten very skinny. I was wondering if there was anything I could do to fatten him up. He is not very active and does not look very good. I have him in a 55 gal. with mainly a Tanganyika/Malawi setup. I have tried feeding him bloodworms, freeze-dried plankton, and flake food at night after I have turned the lights out and the other fish have already been fed. I even tried holding it in front of him and he will not eat it. He used to bury himself all the time and now he just stays in one spot out all the time. I am very worried about him. What should I do?   < These eels are very cool. I saw many different species in lake Tanganyika as few years ago. They ranged from little small 4 inch eels that would swim around like little sea horses to very large ones like fire eels. In the wild we saw them feeding on small shell dwelling cichlids in around the rocks. We caught them at night in minnow traps using very oily fish as bait in the trap. I would catch the eel and place him in a separate tank that is well covered so he won't jump out. Place a layer of fine sand on the bottom and a rock or cave that he can hide in. Make sure the water temp is at least 80 degrees. I would first try some live washed earthworms or some well washed black worms. Then I would get some feeder guppies and throw them in the tank. See if the eel will take the guppies out of your hand. If this doesn't work then maybe small strips or raw fish cut to bite sized chunks. In a large community tank these eels are reluctant to feed because of all the commotion the cichlids create. You eel may end up needing live fish all the time. -Chuck> Thanks, Jessica B.

Freshwater eel Hi there, crew.  It's been a while since I've written.  Last we "spoke" I had gone freshwater only.  I found good homes for my SW fish and corals, and now have a 180 oceanic with a huge sump and bio balls.  I keep the tank at 80 F, and I am using an Iwaki RXLT 40 full blast for sump return.  I do a 30 gallon water change once a week, and clean the overflow sponges at that time.  I run a 40 Watt Aqua UV light on the tank, and use a diatom filter once a week at water change time.  The gravel is a little on the large side, and not really conducive to burrowing.  There are a lot of rock caves, though.    I have four clown loaches (2 are 8+ inches [13 years in my care, so far] and two are 2 inches); 2 small Corys, 9 glass catfish, 2 Plecos.  I was thinking about adding a spiny eel (after lengthy quarantine, of course).  What do you think?  I have read your FAQs, and would like to know what kind of eel might go well in that tank.  I also have another tank (80 gal) with just a couple of dwarf Gouramis that I could place the eel in (he's going to start there, anyway).  Would be interested in recommendation for a fish that did not grow too large and would not eat any tankmates.  I feed frozen bloodworms, Mysis shrimp, flake food and sinking pellets.  My loaches are pretty old and hefty, so I assume that they're happy with the diet. thanks for your help, tom Dear Tom; Tire track eels grow to two feet, and will eat any tankmates that fit into its mouth. Likewise fire eels. There is a pretty eel that grows to around 4 inches called the Short finned spiny eel (Latin name is Mastacembelus zebrinus) if you can find one for sale. Many other eels are either aggressive, grow large enough to eat your other fish, or are brackish/marine. Here is a link for ya: http://saltaquarium.about.com/cs/eelprofilesindex/a/aa082901.htm -Gwen

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.>

African cichlids w/ eels I have been doing some serious research about this and have unfortunately gotten (as usual) conflicting advise on the matter.  First off I love the site, great answers.  What do you know about Aethiomastacembelus elipsifer or Aethiomastacembelus plagiostoma? <Not much. Members of this genus of spiny eels rarely come into the trade in the west> I have an African setup in a 55 gallon w/ black sand and tons of rocks to hide in.  Do you think these guys would do well?  I know to cover any and every hole to prevent suicide and thought about actinic lights  to possibly increase the time spent swimming instead of hiding.  Tell me what you guys think. Thanks, <If the cichlids are not overly aggressive... and you can get the eels in relatively good initial health... you just might have a very nice biotope set-up going. Please write in re your experiences with these Mastacembelids. Bob Fenner>

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>

Boiled Eel.. >Hi, >>Hello. >Wow incredible site. >>Thank you. >My sister has a tire track eel and it's sick, it has boils (?) on its back. That's how she described it to me. >>Sounds like ulcers, an open sore is my take on it.  This isn't good, though. >What might it be and how can we fix it? >>We see ulcers of this type most commonly on goldfish.  It's called septicemia (see here: http://www.fishbase.org/Diseases/DiseasesSummary2.cfm?discode=809 ) >Do you have any good references for info on curing disease/sick tire track eels? >>Not specific to tire track eels, but you can also search for treatments for SCALELESS fishes. >I read on your site that if it has sores it's likely to die soon? >>Maybe not so soon, but these afflictions can be very difficult to deal with.  It should NOT be treated in the main display, however. >She's very found of this eel as she says it has a lot of personality! >>I'm sure it does, and if you can, search further on http://www.fishdisease.net/ as well as looking for freshwater fish forums and sites.  Because these infections can by caused by many bacteria, treatment is rather like "blasting" with antibiotics.  Marina >Thanks, Cindy

Re: A finicky eel? (no commentary?) <Hi, Pufferpunk here.> Ummm, was this supposed to have a commentary on it by one of the crew or was it just being sent back to me as an exact copy of what I sent? <We were having some kind of glitch with this email.  I did respond to you, but something went wrong.  I'll try this again.> A recent update: Over the past few weeks I've had a pretty stable setup in my 55 gallon brackish water setup. A nagging problem of how to get the ammonia, nitrate and nitrite contents down to nothing is my main problem. <Bio-Spira works wonders for cycling problems.> I still think that I'm overfeeding. <Definitely can cause re/cycling problems.> I find that odd even when I have an entire aquatic garden covering nearly the entire sand bottom. A total of 9 voracious adult mollies that devour anything and everything, only judging by taste if it's food or not. I don't understand how I could be overfeeding with how those guys devour food. <Food=waste=ammonia=nitrites.> Apparently of the fry I tried to save, 4 have grown up enough to swim freely amongst the others without fear. Meatball the Tetraodon nigroviridis has been growing steadily, and has actually taken to eating whatever variety food I drop into the aquarium. The two bumblebee gobies seem to be doing well, surviving with whatever bloodworms they can find before the mollies eat them all. I've had no problems aside from with a couple of guppies that I tried to add to the aquarium. When I put them into the quarantine tank, one guppy jumped right out of the water onto the floor on the first night, and the male counterpart died shortly after from fin rot. <Sorry to hear that.> I had also put in a weather loach, who had no problems at all. <Loaches are FW.> He ended up being called Jeac, reminding me of the cleaner shrimp from Finding Nemo. Jeac just cruises along the bottom vacuuming up the sand and siphoning out his gills as he goes along. The entire point of my email is a new inhabitant. The new addition is a spiny eel ( Macrognathus aculeatus), who originally went into my quarantine tank after buying him. It was a low salt content setup with a pH of 7.2, nearly insignificant levels of nitrates, nitrites and ammonia, and had plants to make it look like it had a use to it. After hiding himself under the sand for a little while, he stopped trying to hide at all. Not more than the next day I saw him lazily laying on the sand bottom, taking slow, raspy breaths. He was faded and his gills were a bright red color, and that's why I checked all the chemical levels. I couldn't figure out what it was so I risked tossing him into the big aquarium. I found it very peculiar because in the big aquarium I had JUST done a 40% water change because of a very high nitrate and nitrite level. Even afterwards the levels were higher than the quarantine tank, the salt was much higher with a hardness of 15, and a pH of 7.6. Oddly enough he has recovered, and is much more active. He hides in a log during the daytime hours, and is constantly out exploring at night. My main problem is that I haven't seen him eat anything since I got him, which was 3 days ago. I was told that they eat bloodworms as well, but he hasn't touched any of them when I squirt them nearly right on top of him, and in the end the puffer and the mollies eat all of them. Will he eventually start to eat or is there something still wrong with him that I have to fix to restore his appetite? <Although I have read in a few places that these fish can be kept in brackish, I think they do best in FW.  A little salt will probably be ok, except for the fact that you have a puffer that definitely prefers high-end BW-SW.  My 2 (6") adults are living in SW.  As far as your eel eating (for all I know, the problem has resolved by now after all this time... sorry), are you feeding live black/Tubifex/bloodworms?  Or frozen?  As these are wild-caught fish they are used to eating live food.  Also, some shy, nocturnal types are reluctant to eat in the light, so you may want to try feeding after lights out.> BUBBLES BUBBLES BUBBLES!..... My bubbles! (P.S. apparently I've become the second person in this entire area to have any expertise in brackish water aquariums, the fish compatible and especially the plants that thrive in that water. Looks like doing your homework pays off, although I have still not yet reached the holy grail of balancing the chemical levels in my aquarium. <Sorry to say, those plants won't fair well in high-end BW.  If your puffer is small <2", you still have some time before you need to raise the SG.> <I hope you get this response--Pufferpunk>

Tiretrack Eels 10/14/03 They have not had an appetite for 3 weeks and I am getting worried so please can any one that is an expert on them please help me. <I really could use more info.  These are Tiretrack eels?  How long have you had them?  What kind of food have you offered  them?  How big is their tank?  What are their tankmates?  Have you tested the water?  How often do you change the water?  After you answer all of these questions I'll be much better equipped to help your fish.  Just to let you know, the only food I have ever seen my eels eat is live Tubifex/black/bloodworms.> and if there is a phone #  I could call to give more detail please tell me. <I'm sorry, we have no phone service.  Emails to this address is the best we can do.> thanks Jeff  <Your Welcome, Pufferpunk>

Eel Not Eating 11/16/03
Medium: Brackish water (another one for Ananda I wager)
A recent update: Over the past few weeks I've had a pretty stable setup in my 55 gallon brackish water setup. A nagging problem of how to get the ammonia, nitrate and nitrite contents down to nothing is my main problem. I still think that I'm overfeeding. I find that odd even when I have an entire aquatic garden covering nearly the entire sand bottom. A total of 9 voracious adult mollies that devour anything and everything, only judging by taste if it's food or not. I don't understand how I could be overfeeding with how those guys devour food. Apparently of the fry I tried to save, 4 have grown up enough to swim freely amongst the others without fear. Meatball the Tetraodon nigroviridis has been growing steadily, and has actually taken to eating whatever variety food I drop into the aquarium. The two bumblebee gobies seem to be doing well, surviving with whatever bloodworms they can find before the mollies eat them all. I've had no problems aside from with a couple of guppies that I tried to add to the aquarium. When I put them into the quarantine tank, one guppy jumped right out of the water onto the floor on the first night, and the male counterpart died shortly after from fin rot. I had also put in a weather loach, who had no problems at all. He ended up being called Jeac, reminding me of the cleaner shrimp from Finding Nemo. Jeac just cruises along the bottom vacuuming up the sand and siphoning out his gills as he goes along.
 The entire point of my email is a new inhabitant. The new addition is a spiny eel Macrognathus aculeatus), who originally went into my quarantine tank after buying him. It was a low salt content setup with a pH of 7.2, nearly insignificant levels of nitrates, nitrites and ammonia, and had plants to make it look like it had a use to it. After hiding himself under the sand for a little while, he stopped trying to hide at all. Not more than the next day I saw him lazily laying on the sand bottom, taking slow, raspy breaths. He was faded and his gills were a bright red color, and that's why I checked all the chemical levels. I couldn't figure out what it was so I risked tossing him into the big aquarium. I found it very peculiar because in the big aquarium I had JUST done a 40% water change because of a very high nitrate and nitrite level. Even afterwards the levels were higher than the quarantine tank, the salt was much higher with a hardness of 15, and a pH of 7.6. Oddly enough he has recovered, and is much more active. He hides in a log during the daytime hours, and is constantly out exploring at night. My main problem is that I haven't seen him eat anything since I got him, which was 3 days ago. I was told that they eat bloodworms as well, but he hasn't touched any of them when I squirt them nearly right on top of him, and in the end the puffer and the mollies eat all of them. Will he eventually start to eat or is there something still wrong with him that I have to fix to restore his appetite?
 (P.S. apparently I've become the second person in this entire area to have any expertise in brackish water aquariums, the fish compatible and especially the plants that thrive in that water. Looks like doing your homework pays off, although I have still not yet reached the holy grail of balancing the chemical levels in my aquarium. )

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>

Eel ID hi  my name is Maryanne we have just brought a eel and no one knows what type of eel it is, it has brown coat and dark brown spots and a long head can you tell me what sort of eel it is please. thank you < Hi Maryanne I would need to see a picture of it to say for certain.  It is best to learn about the animals you are going to bring home before you bring them home.  Does it look like either of the eels at the link below? http://wetwebmedia.com/FWSubWebIndex/matacembelids.htm You could also try using Google.com to search for freshwater eels, or marine if that is what you have. -Gage>

My zigzag eels mated, babies? >I just received a call at the office from my wife and my 7 year old daughter, informing me that we have at least a couple of 1/2" long zigzags in the 90 community tank. Hopefully I can catch 1 or 2 before they get sucked into the filter or eaten by the local residents.   >>Fish you *didn't* know were in the system? >Any advice? Should I try and locate/relocate the nest if the rest of the eggs have not hatched? I don't see too much advice.   >>Boy, you're not kidding!  I'm having a devil of a time finding info, too. >If anyone is trying to breed these eels, here is the environment: 90 Gallon AGA 40W Daylight Tube Smooth small river rock type gravel Artificial plants, tall and short Several caves made from slate, as well as many other nooks and crannies. Light on from 6:30AM to 8:30PM PH 6.6 Temperature:  77F Hardness: I forget the number, but it is VERY low. (long island, NY soft, acidic water) Nitrites: 0 Ammonia:  0 Nitrates: < 5ppm Tank Location:  Den where 7 and 9 yr old kids fight and play Nintendo. :-) Besides the 2 zigzags (about 6"), the tank has: 1 Black Ghost Knife (6-7") 1 Fire Eel    9" 5 Congo Barbs 2" 4 Pearl Gouramis 3.5" 5 Red Serpae 1.25" 1 Fat 6" brown (turning yellow) Oranda (don't ask) 1 Male Golden Gourami >>This is a toughie, to get the little ones out (who have survived being eggs and larvae thus far) you'd probably have to tear apart the tank.  Truthfully, I think that if Mom and Dad have gotten down already, they're going to go at it again.  I, personally, would wait and see.  Maybe provide some tubes long enough and thin enough that only *they* can get into, to help along their chances of survival.  Otherwise, I'd leave them be, unless you wish to remove Mom and Dad to their own breeding tank.  If you do that, this may upset their readiness to breed, but if you carefully recreate same conditions, and add the benefits of no food competition and start offering live foods (try to remember if you had done any large water changes, any changing tank parameters, etc. to help figure out what induced spawning) chances are you'll get lucky again with these fish. >Thanks for your help and keep up the great work! >>Quite welcome, and best of luck!  Marina
My zigzag eels mated, babies?
>Hi Marina, >>Good morning, Bruce. Thank you for your advice. I only saw one of the little guys, less than an inch long and very wispy. About all I could find on their breeding is that they lay about 800-1000 eggs.  Based on the size, I would hazard to guess that maybe he was a month old. >>Well, my thoughts are these: first, if *any* of the larvae have survived those initial stages, that's a great sign.  One thing you don't want is to end up with a tank full of eels that you can't house or find homes for. >Looking back, I cannot think of anything out of the ordinary. I have an eclipse 25 with 2 blue diamonds and 20 or so Neons that get a 50% water change twice per week, so while I have the hose out, I give the 90 gallon a 25% change. Filtration is a pair of Eheim 2217's. I also have two air pumps, one on a wand, the other on a stone as I keep the tank pretty well sealed due to having eels. ;-) All of this is on a battery backup. As far as food goes, I feed flake (Tetra Color) in the AM and late PM. After lights out, I feed Hikari frozen bloodworms (the only ones that they and the fire eel will eat) and beef heart. I will keep a log now of water stats, water changes, and feeding. >>It can only help.  And, if there's someone else out there with the eels breeding, or a breeder even, hopefully they'll pipe up and offer some more information.  In any event, I say if it ain't broke, don't fix it. >BTW, your site is great and I have found it a great resource. I am 44 now. When I was a kid I had a few  tanks. I got back into it when it was our turn to take home the kindergarten goldfish about 5 years ago. Went out and bought the eclipse, and then this February, the 90 AGA. My wife isn't a fish fan, but my kids (both with special needs) love it, so she will on occasion put some flake in! Once again, thank you for all of your help and advice. I will continue to be a daily visitor to your site. >>Very good to hear/know.  Glad the site is of such service, too.  Again, best of luck, Bruce.  Marina

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

Yellow spiny tail eel I have had difficulty finding info on the yellow spiny tail eel. I bought one from PetSmart a few months back, and they were unable to give me any info on it aside from the name. This particular store has been known to label their fish wrong, so it could be the wrong name. <Am sure this is a member of the spiny eel family Mastacembelidae, but fishbase.org does not list the common name, even w/o the "tail" in it...> All I know about it is that it's from the same family as the peacock eel and fire eel, right now is 3 inches, cost me $2 (a lot cheaper than my peacock eel), and that it likes live worms instead of commercial fish food. <Most Mastacembelids do> If you could supply me with any info at all, such as how big I can expect it to get (it is currently living with my girls guppies and mollies), I would be extremely thankful. My email is XXXX.                                                             Thanks,                                                                   Josh <Josh, what little we have on this group is posted here: http://www.wetwebmedia.com/FWSubWebIndex/matacembelids.htm and the Related FAQs (linked, in blue, at top). Bob Fenner>

African cichlids and eels??, Eels & Rift Lake Cichlids hey, would a fire eel work in a mixed African rift lake setup?? I currently have a 1-2" frontosa, 2" Malawi blue dolphin, 2 3" Synodontis multipunctatus.. if it doesn't work, r there any other eels that might survive in this.. can u recommend any?? Thanks, Jiwan.. <Well- "survival" is a relative word. Although Fire eels are adaptable to a range of water conditions, I'd probably pass on adding one to this system. Your Frontosa is going to be a BIG fish, and the other fish can be fairly aggressive feeders. Fire eels also get big -more than 3 feet-but they are generally nocturnal and are not competitive feeders. For more info on eels, see ://www.wetwebmedia.com/FWSubwebIndex/matacembelids . Good luck! Scott F.>

Spiny-eel Hi, regarding one of the photos on WetWebFotos.com, specifically the one depicting "Macrognathus siamensis", appears to be of Macrognathus aral, sometimes referred to as the striped spiny-eel. I don't know if you're aware of this, but I thought I would bring it to your attention, I hope you don't mind. Apart from this, I find it to be a very good site, and should improve as more species are added. All the best, Dave Curran <Thank you for this. Will send off to Zo for amending. Bob Fenner>

Hello (Eel? Food, Freshwater?) We live in Iceland, and just purchased a few fish, and an Eel. My questions is, will the eel eat regular fish food? We tried asking the lady who owns the place, but being American over here is a slight problem :) any help would be appreciated. Thanks, Nicole Hatfield <Mmm, depends on what you mean by "regular fish food" and what sort of Eel this is. Please give a read over our site: http://www.wetwebmedia.com/ or use the Google search tool at the bottom of the homepage there... re this issue... Is it a freshwater eel? Do you know more specifically what kind? I have been to Iceland to visit... the local folks take a while to "warm" to new folks, but are genuine, honest people, as you will see. Bob Fenner>
Re: Eel Feeding
<Anthony Calfo with the follow up, my friend> Hey, I couldn't get a good pic of him.....I haven't seen him eat any of the flake food, but not exactly sure where to get more meaty food for him either....at least, not around here.  <fresh seafood if unprocessed will be quite fine from the grocery store. Frozen is better than fresh for safety (pathogen transmission). Squid/Calamari is popular fare for most eels. Shell-on shrimp (even better with legs, head and innards) is also an excellent source of protein and good for keeping teeth worn. Resist fatty (oil) fishes for tank water quality. As a rule, Crustacea are better fed to eels than fishes. And whole fishes (guts and head) are better than fillets.> I do however think he helped to kill our algae eater. Not positive about that though.  <wouldn't be a surprise> Will do what I can, and will try to find a pic of him tomorrow. Thanks again for all your help. Nicole Hatfield <do look through the photo archives of eels on www.fishbase.org if a picture is not convenient for you. Best regards, Anthony>
Re: hello, Iceland Eel
Yes, I do love it here, but still not sure about the people :) and yes, all of her fish are freshwater fish. He is probably 2 inches long, and all brown in color. The pet shop owner gave me the flake fish food. She said it was for all types of fish. I have no idea what kind of eel he is. And I can't find a pic of him anywhere. I wasn't sure who else to ask, and from your website, you looked to be my man. If you want, I can catch him, and take a pic with our digital, if that will help any. Let me know, and thanks for all your help :) Nicole Hatfield <Please do send an image along. Does the fish seem at all interested in the prepared food you have? You will likely need to offer something more meaty... There are several choices here. Let's try to get a handle on the type of fish this is. Bob Fenner>

Eels Healing from Injuries Hello Once again Dr Fenner! <Anthony Calfo in your service, my friend, whilst Bob travels the great continent of Australia. I'm hoping he brings me back a cool accent instead of a tee-shirt when he returns <smile>> I need your advice regarding these 3 fire eels that I want to buy. The aquarium houses them together with a grown Cichlid in a 2 ft tank. I think the Cichlid must have attacked them before 'cos I can see that 2 of them have slight injuries. <a shame...mitigated by the cramped tank I'm sure> The 3 eels are about a foot long and are very fat. The injuries are such that I can see the whites of the flesh. The body is jet black but then I can see breaks in the skin that reveal the whites. It actually looks like a small scratch made by a needle. The injuries look very minor but I do want them to heal if I decide to purchase them. Its very rare over here (Singapore) to get eels at this size. <perhaps because they are delectable <wink>> Do you have any recommendations for medication? What can I do to help the eels heal faster?  <yes... an antibiotic combination of Furazolidone and Nitrofurazone (Jungle brand "fungus eliminator" for example). Eels are one of the few fish prone to true fungal infections. It will guard against bacterial infections as well> If I just put them in my tank will the injuries eventually heal?  <perhaps...especially if your tank is larger (it really must be)> I went back to the aquarium about a week and a half later but the injuries were still apparent.  <unusual and not a great sign... perhaps you should take them sooner to a better tank> They look pretty relaxed in the tank though but I think they'll be better off without the Cichlid. <certainly agreed> On a separate note, what kind of medication are suitable for eels with fungus or other skin problems? <above listed...and antibiotics in general are safe> I read that they are very sensitive to metals in the water and also some 'itch' medicine.  <yes... avoid copper and organic dyes like malachite and Victoria green and Methylene blue> Should I put in some capfuls of Blackwater into the tank? Will this help them relax? <dim lights will work the same or better> You helped me identify the Caecilian I have several weeks ago and I really am grateful! =) I look forward to your reply once again. Yours Faithfully, Leonard Emmanuel <with kind regards, Anthony>

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>

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