Fire Eel (Mastacembelus erythrotaenia) Advice?

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Shard

Feeder Fish
Feb 26, 2016
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Hey everyone,

Been out of the hobby for a couple years, with college stuff and work. Hoping to splurge a bit of my savings to pick up a 100 gallon fish tank. I've looked at a lot of large fish to put in this size tank (Which is a pretty wide range of fish), but none captured my attention more than the Fire Eel.

It's always been my dream to own one of these legends, but I never got around to setting up a large tank for it, nor did I have the funds to do so.

But now I've got a little cash and more patience, so I'm hoping to make this eel the capstone of all the fish I've owned.

Problem is, there's only so many articles you can read and quite a number contradict each other. For example, I've heard you need anything from a 55g to a 200g tank to house a single one of these fish through its life. Feeding has been vague, no one says anything about tankmates. Everyone says to secure the top of the tank, but no one says how.

So, I'm hoping there's one or two people here that have handled a fire eel. If you have ever owned a fire eel for a reasonable amount of time (Preferably 6 months or longer) successfully, please PM me! I just have a series of questions for someone with actual experience with these beauties.

My primary questions include:

1. Tankmates - Can I keep anything besides gigantic cichlids with 'em? I really like the idea of a dinosaur bichir and especially a black ghost knifefish. Just something colorful to keep the tank stocked with diversity. Recommendations?

2. Feeding -
a. What to feed them throughout their lives? I see they like mosquito larvae and live bloodworms while young, are those the best options?

b. Do they absolutely need live food that need a tank to culture their food?

c. Do they need any vegetable supplements due to their omnivorous nature?

d. I hear they take nightcrawlers and small pieces of fish when older. Where would I acquire clean specimens for feeding?

2. Decor

a. I know they need hiding spaces. Driftwood needed? What kinds are non-abrasive? How much would I need, since it’s traditionally so expensive?
b. Would investing in a clear PVC pipe be a good investment? Would he actually use it?


c. Depth of sand substrate? What kind of sand?

3. Security

a. What kind of lid should I get? How do I make it escape-proof?

b. How do I make the filter intake/output areas escape proof?


4. Filtration –

a. What kind of filtration is best? Canister?
 
1. Tankmates - Can I keep anything besides gigantic cichlids with 'em? I really like the idea of a dinosaur bichir and especially a black ghost knifefish. Just something colorful to keep the tank stocked with diversity. Recommendations?

ANSWER: As long as they are peaceful and large enough not to fit in the eels mouth it shouldn't be a problem

2. Feeding -
a. What to feed them throughout their lives? I see they like mosquito larvae and live bloodworms while young, are those the best options?

ANSWER: I used to feed my old eel cut up pieces of frozen shrimp / mussels / scallops / live freshwater prawns / never had any luck with any dried foods...

b. Do they absolutely need live food that need a tank to culture their food?

ANSWER:Depends on your eel, most will eventually take frozen foods, but dry foods such as pellets are very rarely accepted from what i've experienced and seen

c. Do they need any vegetable supplements due to their omnivorous nature?

ANSWER: Wouldn't hurt, but doesn't need to specially add it...

d. I hear they take nightcrawlers and small pieces of fish when older. Where would I acquire clean specimens for feeding?

ANSWER:If you have an full organic yard you could grab them from there given no pesticides are used, otherwise, maybe try a fishing store or something similar and see if you can grab worms there???

2. Decor

a. I know they need hiding spaces. Driftwood needed? What kinds are non-abrasive? How much would I need, since it’s traditionally so expensive?

ANSWER: Driftwood works, any Malaysian / Manzita wood should work, you basically want to create cave like structures for them

b. Would investing in a clear PVC pipe be a good investment? Would he actually use it?

ANSWER: Yes, that is an alternative, grab a few pieces, with elbows added and you can create different size caves for him to live in

c. Depth of sand substrate? What kind of sand?

ANSWER:Deep enough for them to feel comfortable, so i would say 1" or more would be fine... just make sure its fine, and without rough edges that could hurt the eels body...

3. Security

a. What kind of lid should I get? How do I make it escape-proof?

ANSWER: Depends on the type of tank you have, but acrylic or glass sheets weighed down works...

b. How do I make the filter intake/output areas escape proof?

ANSWER:Again, depends on tank setup, but basically you could use different types of rubber matts, netting etc to cover any space around the intake areas from the lids...

4. Filtration –

a. What kind of filtration is best? Canister?

ANSWER: Whatever works for your tank to give you enough turn over for the amount of stock you have, canisters / sumps / HOBS all work, just make sure its enough for the size tank needed

Lastly as for Tank size, i would say nothing less than a 200G for an adult would do, considering they can and do reach up to 3' in length and get pretty darn thick...
 
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Great post Homer,I have been considering adding a fire eel to my tank but I'm not sure how my afer knife fish will react to it.
 
^ Thanks, and i've never kept a knife fish before, so can't say for sure how they will work out together, i have however seen fire eels that seem to be a little pushy, but because they don't have sharp / long teeth, they can't to do too much damage...

For example, my old eel used to nibble on my fingers if i had been chopping up food getting ready to feed the tank, and doesn't hurt at all... the only thing is really the eventual tank size for these fish and making sure the you literally cover any and all holes that the eel could escape through, since mine managed to get out of a hole i never expected it to fit through when it was around the 23" - 24" and thicker than the hole it got out of...

One other thing i forgot to mention, don't try and handle these eels either, since they do have very sharp spines on their back, (hence the name spiny eels i guess), found that out the hard way the first time my eel jumped when I left the tank lid open to cool down the tank :P
 
Were you able to save your eel after it escaped through that hole?
 
Unfortunately no, the 2nd time he jumped (which was through the hole) it was in the middle of night, so my g/f and i woke up in the morning to a black snake like creature about 3' from the tank...
 
Unfortunately no, the 2nd time he jumped (which was through the hole) it was in the middle of night, so my g/f and i woke up in the morning to a black snake like creature about 3' from the tank...
I can imagine your dismay over not being able to save the eel.I would hate to have something like that happen.
 
I've heard most fire eel accidents or premature deaths are caused by jumping. Hoping to prevent that in any way I can.

A piece of information I should have mentioned earlier. I'm leaving for a 4 year university in a year and a half. That's roughly the length of time I will possess this tank. Don't worry, I don't intend to kill any fish I have, I have multiple reputable LFS's that would be happy to acquire such rare beauties, especially if they had grown out a bit.

That being said, do you think something smaller than 200g would suffice to house an eel for 18 months? What would be your minimum tank size for it for that period of time?

Whatever size you recommend, it would most likely be a standard size tank, nothing fancy like acrylic or oddly shaped. But I was surprised to see you suggested a pane of glass to keep the eel contained. Would that not prevent gas transfer, and deplete the oxygen quickly? Did you have to drill holes in the glass to get the filter intake and output through?

Oh, and how did your eel finally escape? Where was the hole, and how could a similar tragedy be prevented?

I know that's a lot of questions, but I'm a cautious guy and Fire Eels are really the pinnacle of my interests. I've run 4 tanks at once before, 3 of them planted, and bred sensitive fish and shrimp. But nothing came close to how much I wanted a Fire Eel. I would hate to have mine escape to an unfortunate end!

Thanks again
 
Hard to say minimum tank size, since it depends how big the fish is when you buy it...

I mean mine for example went from about 10" to 20"+ in about 2 years time, and the younger they are the faster they grow, especially once they learn to eat...

Also, for your information, it took me 6 months just to ween mine off live food, so that should be another consideration of yours... But again, once that happened, it grew like weed...

As for the covers, i cant answer you on the gas exchange problem, but holes in the lid sounds like a good idea...since My tank has a very heavy hood over it, so i dont need to worry as much...

However it was just the holes where the intake and outflow go in and out that the eel squeezed through somehow...

I have since solved that problem by covering that whole area with soft rubber padding, since im now keeping 4x Gymnothorx Polyurandons and dont want to risk losing any of them...
 
Here is an example of one end how i covered the intake area...

image.jpeg
 
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