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FAQs about "Freshwater" Morays Eel Systems

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

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

"Freshwater" Moray Eel Two Questions, fdg., sys.    4/1/12
I want to start off by first thanking you guys for your wonderful site!
<Thanks for your kind words.>
I have been maintaining my brackish water tank using all of your incredible advice. Well on to the questions....First off I have a 40 gallon brackish water tank PH is at 8, nitrates and ammonia levels are all normal and temp is kept at 80 deg F. Started off by having gravity level at 1.010, but have slowly over time raised it to it's current reading of 1.021. In the tank I have a "freshwater moray eel" or as you refer it to a Gymnothorax tile, a green spotted puffer and a "freshwater" flounder/flatfish.
<Not the best tank mates, these eels can become really incompatible when growing up.>
I first purchased my eel about two months ago and of course he went on a hunger strike, but after raising the salt levels to 1.021 the eel has been eating. My concern is he is eating like crazy! He accepts food by tweezers and his diet is consisting of freeze dried krill, shrimp, muscles, silverbacks, ghost shrimp and tilapia (I like to keep his diet varied). I read on your site that juveniles tend to eat every other day and adults eat twice a week. My eel eats two times a day each time taking two different foods. He doesn't seem to just be stuffing himself because when he has "had enough I guess" he goes back into his cave. Is this normal for him to eat like this??
<Oh, that's what I often ask myself about some people.>
I feed him at a specific time in the morning and at night and he is readily waiting for me, sometimes barely letting me get the food in the tank. When I first got him (assuming its a he) he was very skinny about the circumference of a dime and 11in long. Now he is almost the circumference of a nickel and 13 in long. My question is, should I keep his feeding habits the same, or if not what amount he should eat?
<You offer much more to him than nature does in my opinion. I'd feed significantly less, about the size of the eel's head per feeding. Feeding every other day is sufficient. There are some reports on the negative results of overfeeding moray eels, e.g. by P. Purser in the TFH book and there are examinations of eels caught in nature showing they don't eat every day (some larger species only once per week or less.>
My next question is, I read that when juveniles, the eels live in brackish water and eventually move to full saltwater when older.
If this is true, when should I convert to a full saltwater tank?
<It's easier to maintain, because you can use a skimmer, live rock. You've almost reached marine salinity, so I see no reason to not convert to full saltwater.>
Thank you so much for your time and I look forward to hearing from you!
<Also see: http://www.wetwebmedia.com/ca/volume_4/V4I2/Freshwater_eels/freshwater_eels.
htm . Cheers, Marco.>
Re: "Freshwater" Moray Eel Two Questions   4/1/12

Thank you very much for responding so quickly!
<No problem.>
I am going to reduce my eel's food starting today. Do eels beg?
<If by begging you mean that they expect to get food from a known source: yes. In some areas moray eels accumulate below the nets of large offshore fish farms. Every time the fish within the nets are fed, the moray eels come out to get their share, which falls through the net.>
Lol, because that is going to be the hardest part in reducing his diet. He literally "begs" by sticking half of his body out from his cave and faces towards the surface waiting for me to feed his fat butt when I come in the room every morning. In regards to his tank mates the green spotted puffer and the flatfish, so far the eel is very accepting of them, but I will watch as he gets older to see if he acts aggressively towards them. Thanks again for all of your help!
<Welcome. Marco.>

freshwater <moray> eel tank     5/29/12
I just bought a 45 gallon tank on craiglist and it came with a bichir, 4 cichlids, and a freshwater eel. It is a full freshwater tank and after reading the information on your site i understand the freshwater eel must be in at least .01 salinity.
<No, much more than that. SG 1.005 to start with, and with the understanding adults need SG 1.010 to fully marine conditions. If the salinity is too low, they invariably approach maturity but stop feeding, and then die.>
Is there anyway that i can keep all these fish in the same tank?
The guy i bought it from said he's had this setup for about a year and half and the eel for a year and he feeds it crawfish and ghost shrimp. I also have a my own quarantine tank that has had feeder guppies in it for at least 2 months. Is it safe to feed those to it?
<I don't recommend the use of feeder fish bought from the pet store, no matter how long you've kept them. But if you breed your own feeder guppies, and you've dewormed them, then their offspring may be safe. Still pointless and risky, but less immediately dangerous than using store-bought guppies or God forbid goldfish. Much said about "freshwater" moray eels here at WWM; but do also check you aren't talking about a Spiny Eel, which are true freshwater fish, albeit ones that prosper from having a small amount of salt added to the water. All this and more is already up at WWM, so read:
Cheers, Neale.>

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

Regarding the brackish moray eel (commonly sold as freshwater)    10/2/11
Hello.. I just want to ask a simple question. Well, my LFS has a brackish moral eel (they say that it's freshwater, but what do they know, right?)
<Apparently not about this animal's needs>
So yeah.. I'm interested in buying one.. I know that they require brackish water conditions.. I just want to ask that the LFS has the eel in freshwater conditions. So, if I were to buy it, should I just shift it
directly to a brackish tank with a specific gravity of around 1.011 or should I acclimatize it to brackish water? And if I should acclimatize it, would you please give me some tips on how to properly do so?
<Should be shifted to brackish, but slowly... perhaps a thousandths (0.001) per day or two... with the addition of pre-made synthetic sea salt (not table, kosher, ice-cream... types), or real/natural seawater if you're close to a clean source. Mmm, please read here:
and the linked files above. Bob Fenner>

Recently purchased freshwater snowflake eel   9/11/11
Hello all, yesterday I picked up a freshwater snowflake eel for my currently freshwater tank. The petstore told me I might have some problems getting the eel to start eating. Which is fine, both yesterday and today he was very active swimming around everywhere. To my understanding, he was getting used to the tank. Later today he seemed to have stopped moving and started settling in, but then I noticed he was lying on his back. Since I first noticed this it has continued. He still swims around for bits at a time but then he comes back down and when he does he is occasionally on his back or side and I'm not sure why. Is this a sign of illness, is this normal? If illness what can I do? His breathing doesn't seem particularly heavy or fast or anything. But I've had him for a day so I'm clearly not experienced to make such a judgment. I'm hoping I'll hear that he's fine and its just something he'll do but if not please let me know how can I can better care for this creature. Thanks for all your help.
<Hello Aria. The "freshwater" Snowflake Eel is in fact a brackish water to marine species, and the pet shop should have told you this. Indeed, you should have hopefully learned this before buying such a challenging pet.
The most common species traded is Gymnothorax tile but there are one or two others sold from time to time. They all have very similar needs. What you describe -- not wanting to eat -- is extremely common when these eels are kept in freshwater conditions or brackish water that isn't salty enough.
You need at least 25% normal marine salinity, i.e., about SG 1.005 at 25 C/77 F for a young specimen, and for long-term care, about 50% normal seawater salinity or greater, i.e., SG 1.010-1.025 at 25C/77 F.
Once settled down, they feed readily on small live foods like river shrimps, and quickly take good wet-frozen and fresh foods such as cockles and tilapia fillet. Minimise the use of Thiaminase-rich foods such as prawns, shrimps and mussels. Do not use feeder fish at all.
Morays are nocturnal feeders and prefer shady tanks, but given time, will feed during the day. But to start with, place small bits of food in the tank during the evening with the lights out. Don't overfeed.
Cheers, Neale.>
Re: Recently purchased freshwater snowflake eel   9/11.5/11

Hey, I know they are brackish, I should have indicated that prior. When I said it is currently freshwater what I meant was that I was going to acclimatize the tank to brackish once I got the eel.
<Would get this fish into brackish water ASAP.>
I have a couple of dragon gobies in the tank intending it on being a dragon goby/eel tank.
<Dragon Gobies need brackish water, and won't live indefinitely in freshwater. Surprisingly perhaps, Morays aren't good community fish, and often bite fish they can't actually kill. Be very careful when keeping them alongside other fish. Has been done, yes, but "your own mileage may vary".
Would prefer an Echidna species to a Gymnothorax species if that was your aim; Echidna spp. feed primarily on invertebrates rather than fish, so are less prone to biting.>
Sadly, this morning, my eel seemed to have passed, lying on his back not moving. Clearly something was wrong as of last night. I will admit, I am not well versed in tank maintenance but I thought I new enough to be trustworthy with these creatures.
<They are actually very easy to keep. But they DO NEED brackish water, and keeping them in freshwater even for a few weeks DRAMATICALLY reduces your chances of success. The irony is that in marine aquaria most moray eels are considered very hardy fish!>
My Goby's have been in the tank for two months now and they are fine and thriving, as far as I can tell. My question is, what could have gone wrong to cause the eel to get sick and die within two days of purchase, and how could I have reacted to treat the guy?
<Maintained too long in freshwater. Weeks, months at the retailer, and then weeks, months at your home. All too stressful.>
I want another eel but as I'm sure you'll suggest, not to get one until I can resolve my tank issue, so please, any help would be greatly appreciated.
<Do read Marco's piece; it covers everything you need to know. These are really very hardy animals, but upon purchase acclimate to brackish water conditions immediately. No less than SG 1.005, and preferably 1.010.>
Like I said, I thought I did my research but I guess not enough.
<Good luck next time. Cheers, Neale.>
Re: Recently purchased freshwater snowflake eel   9/11.5/11

 I've been going through the posts you've sent, and I appreciate all the help you've been providing so far. If you don't mind, I do have a question or two.
First off, if I add salt into the tank what are the chances my eel (who is actually not dead but just moving very little to not at all) will turn out alright?
<May help; certainly can't harm.>
If salt isn't enough what else can I do? Further, my understanding was to do a slow acclimatizing of the tank. At what rate should I be increasing the salinity of the tank?
<The problem is the filter bacteria rather than the fish -- these brackish water eels and gobies can acclimate to seawater from freshwater within an hour. They have to, when the tide comes in! But filter bacteria need to be gently coaxed into brackish/marine mode, so you have to go slowly here. If your tank is a freshwater one now, you can raise the salinity to SG 1.003 today without any risk to your bacteria, but after that, you'll need to make small changes weeks or months depending on how big the change. If you look on my web site there's an application called Brack Calc that converts specific gravity to salinity (including grammes of marine salt mix per litre) for any given temperature (25 C being normal). Use this to estimate how much salt to add to your aquarium. For example, let's say you remove 50% of the water in the tank, and replace with water at SG 1.006, i.e., 10 grammes marine salt mix per litre of water. Because you've changed half the water in your tank, you have half SG 1.000 and half 1.006 in the aquarium, for an overall salinity of SG 1.003. Perfect! Use a hydrometer if you have one to check, but weighing out the salt is close enough for this.>
Thank you so much, I have been looking online for tips as well as emailing you, I just really want my eel to live.
<Marco L. has written extensively on these eels, and there's much here at WWM you'll find useful. Good luck, Neale.>
Re: Recently purchased freshwater snowflake eel   9/11.5/11

<PS. the link is:
It's free, and works on Mac and Windows. Cheers, Neale.>
Re: Recently purchased freshwater snowflake eel   9/11.5/11

Thanks, I found it. I'm pretty sure my eel is officially dead. There are black spots now on his stomach and he's not moving at all. Unless you advise otherwise, I will be removing him from the tank soon. In doing a water change I added sea salt
<Marine aquarium salt, not "sea salt" used for cooking or tonic salt/aquarium salt used in freshwater tanks. Must be marine aquarium salt mix, like Instant Ocean, Reef Crystals, or similar.>
to my tank (as suggested by the store) and the salinity of my tank looks to be just under 1.004.
I know you said its safe to bring it to 1.003 right away, should I be concerned by this slight elevation?
Also, at this point, how much should I be raising the salinity per week or two weeks or whatever?
<The aim would be to go to SG 1.005 in two weeks' time, then leave it there for a few months. After, say, six months, or sooner if your Moray stops eating (a common problem when it isn't salty enough for them) incrementally raise the salinity, for example from 1.005 to 1.006 in two weeks, then 1.006 to 1.007 in another two weeks, and so on. This gives time for the freshwater bacteria to die back and the marine bacteria to multiply. By the end of the year, it'd be nice to have the tank at 1.010.>
And now that the salinity is being raised do you think I can get another or should I wait?
<You might want to leave the tank with just the Dragon Gobies for a couple of weeks just to make sure ammonia and nitrite levels are zero. No point adding MORE livestock if the filter bacteria aren't happy. Go slow. Better to delay adding new fish for two weeks than to buy your Eel tomorrow and end up with a nitrite spike and sick fish.>
Also, I got the pet store to check my water levels and according to them everything is ok.
<Would, at minimum, own a nitrite test kit and a pH test kit, plus the hydrometer.>
Let me know if I'm on the right track and if not how to properly orient myself. thanks!
<Do read, go slowly. Cheers, Neale.>
Re: Recently purchased freshwater snowflake eel 9/12/11

Thank you so much for everything. Your website and what you guys do is awesome and of great help. Just to clarify, the sea salt I got was instant ocean sea salt, I assume that's still ok since you seemed ok with the salinity level my tank is now. Once again, thank you so much.
<Glad to help. Yes, 1.004 should be fine for now, but as/when you get a nice, healthy, fat-looking Moray settled in and feeding, you will want to gradually inch that upwards towards 1.005 for the first 6-12 months, and somewhere between 1.008-1.012 thereafter, or sooner if the Moray goes off its food. These are really very straightforward animals to keep, provided you understand their need for brackish water and a diet with not too much Thiaminase.
Cheers, Neale.>

True Freshwater Moray found? Impossible? 02/06/09 Hello, Hello Moray Experts :) <Hi Trevor.> Trevor here with some fairly interesting things to discuss, it seems, perhaps, as supported by about.com and Fishbase that there is, perhaps a true freshwater moray? Even the About staff seem to have been confused at first but say it's confirmed. If not it seems they should be corrected ASAP because it was very misleading if they're wrong. <Feel free to do so, the text is around since a few years.> The eel in question is Gymnothorax polyuranodon. <Ah know it, kept it.> Supposedly they've dug deep into their research, whatever that may be, and found that this moray lives primarily in fresh water. It seems suspicious, as I look over to my Gymnothorax tile next to me and think that they must be confused. Certainly, it's a brackish fish, as they list it as venturing into brackish water, right? <G. tile mostly occurs in mangrove swamps with high salinities or 100% marine salinity during the dry season. It also travels up river mouths, possibly to get rid of parasites or to breed. In captivity it does best in a marine tank.> I found all this somewhat interesting and wondered if it could really be true. One more question, would you happen to know the pricing on this "Spotted Freshwater Moray?" <The ones in Europe cost the equivalent of about 60-80 USD in the stores, they only available every few years.> Even if they are brackish, I've been thinking about getting another moray. These are quite attractive. Fishbase: http://filaman.ifm-geomar.de/Summary/SpeciesSummary.php?id=17227&lang=English <I exchanged your link, because the English server seemed to be down when I tried.> About.com's "Freshwater" Moray list: http://saltaquarium.about.com/cs/eelprofilesindex/l/blfweels.htm Thanks, Trevor <Trevor I know the text at the site you linked to and have most of what is known to science re this eel as well as own experiences and reported experiences of others from the pet fish trade. As you can see G. polyuranodon occurs in various habitats from freshwater to marine, was found as far as 30 km away from the coast. Its even speculated this eel could be catadromous (living in freshwater, but travelling to the sea at breeding time), you can call it an euryhaline fish. With regard to its captive care, Ive tried everything from freshwater to marine and have to state that they did by far the best in a marine tank, while the ones left in freshwater at the shop did much less well, refused to eat with time, looked much less vibrant. So, G. polyuranodon does much better in freshwater than its G. tile cousin, but still at some point of care you will not be able to avoid salt completely without endangering the health of the animal. But it is a great pet and truly justifies the additional costs related to a marine setup. Have a look at the WWM articles on freshwater moray eels: http://www.wetwebmedia.com/fwsubwebindex/fwmorayeels.htm and http://www.wetwebmedia.com/fwsubwebindex/fwmorayart.htm No pet moray without salt. Sorry. Marco.>

Re: True Freshwater Moray found? Impossible? II, fdg., sys.  02/07/09 Hey again Marco, <Hi Trevor.> Well, a question about the other eel, (not G. tile, but polyuranodon). How hard is it to get them to eat? <Just the same a G. tile or other morays. May take days to weeks, but given pristine water conditions and salt theyll eventually start eating. G. polyuranodon is a little more shy, and although they may become longer than G. tile, they are even slimmer and remind me somewhat of ribbon eels.> My G. tile eats just fine in his brackish water setup and even comes out to investigate his tank at night. ...and one last thing. Is it normal for a G. tile to bulk up? <Yes to some extent about once a year I notice a slight gain of girth. I guess that may be prior to their breeding time. With age they also become a little more stout.> I've seen the small, skinny ones all the time though, I'd like mine to pick up some weight. He does eat regularly, but he just does not eat all that much. It's as if he's set to eat a predetermined amount every day. <Just dont overfeed. This can cause liver problems in the long run. If it does not want to eat anymore, its okay.> He's healthy, a deep gray/blue color with tiny bright-yellow spots on him. The mollies don't stand a chance, and the bits of squid, octopus and silversides are relished as well. I try and rotate his diet to give him enrichment and some good nutrition. I think I'm doing everything correctly so far. <Yes. You can add fish vitamins once a week to the frozen foods.> The eel is very responsive to food and is always looking out across the room from his PVC pipe that's buried in the gravel. Speaking of gravel, is it better to keep them on sand or gravel? <Does not matter.> The guy at the fish-specialty store told me morays prefer sand to gravel but... I always see them in reefs where there's no sand, and they certainly don't hang out in the open all day although I do know from videos online that they come out at night and hunt for fish among the rocks and coral. <As G. tile comes from mostly mangrove swamps and estuaries, a fine grained substrate like sand does resemble its natural environment more closely. However, for captive care it does not matter, the usual aquarium gravel or even better crushed coral is fine. Just avoid substrates with sharp grains. Personally, I prefer sand for the moray tanks, too, for the purpose of natural denitrification, which takes place in well populated marine sand beds. As a side note, many moray eels do not inhabit the reefs, but sea grass beds, gravel fields and muddy bottoms.> Any further advice? Thanks, Trevor. <You seem to be doing very well. Marco.>

Gymnothorax tile, hlth./env.  9/25/08 alright, i got one of these guys out of a freshwater tank, however he didn't seem to be doing so well. <This species never does well in freshwater aquaria, at least not for long.> then i researched and found that he was a brackish water species. so i added sea salt, but added too much over a long long period of time. my salinity is 1.025 as of now and let me tell you, he has grown at least 6 inches and is doing great in full marine water. <Not a problem for this species. Wild fish live in river estuaries, and can tolerate rapid changes in salinity well. Maintenance at marine salinities is not harmful, and in fact mid brackish (SG 1.010+) to full marine conditions are perhaps the ideal.> is this eel actually a marine eel? <He can be, without any harm at all. In the wild they don't live permanently in the sea, but like most brackish water fish, will do just fine in a marine tank.> he seems to be doing better in the full marine than he was in the brackish water! he's in a 12o gallon tank, FOWLR. <I'm sure he's very happy! Enjoy your pet. Cheers, Neale.>

29gal G. tile 09/06/08 I have a 29 gallon tank that for the longest time was brackish with HOB filters. I once had 3 GSP's in it, but they grew up and were given to a friend. It now houses a g. tile of around 10 inches. I have moved the sg up to 1.025 from 1.015 and ph to 8.4, got some actinic and 10k lights, and a SuperSkimmer that isn't giving any problems other than the skimmate is wetter than I'd like. <Should be adjustable with the water-level adjustment dial.> I put 9lbs of live rock in there, with more to come as money allows. <Good.> Strangely, the eel has really taken to the LR, he seems much happier with it around. There are also mollies of various sizes, a population that has been in the tank for food since it was first cycled. I'd say, maybe 3 left over an inch that he hasn't eaten and perhaps 30 under a half inch, the eel waits until they are bigger to eat them. <Interesting!> Everything else in the tank is zero, nitrates before dumping the liverock in were barely being kept under control. Waiting a few days to test after adding the liverock. Is there anything you can suggest to keep the nitrates under control between water changes? <Replace the HOB with a powerhead and more good live rock (up to one pound per gallon or even a little more). That alone might solve the issue if your freshly mixed water is free of nitrates and the tank is not overfed. Another possibility would be to use an overflow (secured with a net or mesh because of the moray) and a second tank (aka sump) with a refugium with a DSB and macroalgae. Reduce the number of the Mollies, if the eel does not eat them as they are growing. Also see http://www.wetwebmedia.com/nitratesmar.htm and the linked FAQs.> I am considering building a coil denitrifier to keep the water changes to every 2 weeks instead of twice a week. <Would be a possibility, too. Many construction plans are found on the internet. However, if this thing does not work as intended, it can poison your tank. So, when you decide to take this path Id recommend to invest into a RedOx (ORP) measuring device and ideally an automatic shut-off if the ORP in the water flowing/dropping back into the tank is too low. Cheers, Marco.>

Snow flake in upper end brackish tank? (RMF, please check)  2/24/08 hey guys and gals, ????????????????????????????????? I just recently set up a 40 long as a brackish tank. its been running for about 5 days already and I put in some "test mollies" to see how the water is. the mollies have been eatin and seem fine. my ph is 8.2, SG is .014 and I have a mixture of sand and crushed coral. I originally was gonna get a "fresh water" (really brackish) moray eel (g. tile) but ended up getting a 7" snowflake. I slowly acclimated it over 2 hours into my brackish tank because it came from full salt water. its been about 5 days and it seems to be doing fine (eating well). can this specie be kept in a upper end brackish tank? has anyone done this with a snowflake or am I ultimately cutting his life short? thanks!------------------> Ronnie <Gymnothorax tile is indeed an estuarine moray eel and tolerant of a wide range of salinities, but to the best of my knowledge Echidna nebulosa is not. While it may do well for a while at a reduce salinity, I can't imagine it can be kept indefinitely in brackish water, at least not below SG 1.018. There is nothing to stop you maintain brackish water fish at SG 1.018+, and indeed Monos, Scats, etc will positively thrive in marine and near-marine conditions. So I would suggest that doing that would be a better way to keep this fish. Alternatively, return the Echidna nebulosa to the pet store, and keep your eyes peeled for Gymnothorax tile. Finding Gymnothorax tile is not difficult; it is quite a widely traded species, and any half-decent aquarium shop can get it in as a special order. Cheers, Neale.> <<Hard to say/state which species this young person is referring to... I'd put the onus on them to look up, identify... RMF>>

Re: snow flake in upper end brackish tank? (RMF, please check), not brackish...    2/27/08 its not g. tile its echidna neb. <Mmm, please read here: http://wetwebmedia.com/snowflakemoray.htm and the linked files above. This Moray should be kept in full-strength seawater. Anything less will shorten its life-span. Bob Fenner>

Acclimating a moray eel from freshwater to brackish  03/23/07 I am considering getting a Gymnothorax tile from an LFS that has a relatively small one 6-8", but is in freshwater. I have a brackish water tank and was wondering what exactly I would need to do so that he would be ok. <Put the moray eel into a container with aeration and add a lid. Slowly add water from your brackish tank for about one to two hours until the water in your bucket consists of about 70-80 percent of tank water. Carefully transfer the eel to your display tank. You may also use drip acclimating. Their natural habitats in part have diurnal cyclic salinity changes, so this procedure can be considered safe. I did use it to transfer them from freshwater to marine and did not experience any problems.> Would I have to place him in a separate tank and slowly raise the salinity? <It is not necessary, but you could do that, if you had a cycled tank with a lid. Do not increase the specific gravity more than 0.003 per week to avoid killing filter bacteria.> How much time would it require for this process? I have a 5 and 10 gallon tanks not in use and if I could get away with it I was wondering if one of these would suffice to get him acclimated to brackish. From my understanding suddenly placing fish in lower salinity is not nearly as dangerous as placing them in higher levels. Is this true? <In general: yes.> As far as feeding goes, would ghost shrimp be suitable along with guppies with this species? <Yes, but only to get it to eat. Their diet should be more varied, frozen seafood from the grocery store is perfect.> Thank you. <Welcome. Cheers, Marco.>

Eel needing a hiding spot 03/08/07 Hi, I realize there are tons of questions posted and Ive read a lot of them. Unfortunately, I also have school work and the tons of projects that arise every time I look at that tank. Anyway my most recent problem is a nitrite spike. <Nitrites (not to be confused with nitrates) are quite toxic and should only occur while cycling a tank.> The fish are taking it well with the exception of the princess parrot, <Good luck with this fish. I hope he is big enough. Have a look at http://www.wetwebmedia.com/pufferFAQs.htm and search for princess parrot.> who is now waiting it out in a local fish store, while I fix the problem. Anyway, because of this spike Im trying to find out about my snowflake eels recent new behaviour. Him and the chainlink eel used to pal around in the rock pile I put together for them. I recently restacked the rocks to keep other fish out that didnt need to be in there. The new stack seems to allow for more light to get in through the cracks. The chainlink eel is still in the rocks, but the snowflake is wrapped around my pump at the top of the tank in a darker corner. He usually eats when offered and Ive been using the eating as an indicator that they are not getting too stressed out by this latest nitrite spike (the chainlink still voraciously seeks food). Either way, is this new hiding spot of his, because theres too much light in his old spot <probably> or an indicator that the nitrite is pushing him a bit too far <wont be good for him anyway.>. Please let me know so I can help him fast if he needs to find a new home for a little while. -James Williams. <An excellent article with ideas for hiding spots for moray eels is found at: http://www.wetwebmedia.com/ca/volume_3/cav3i1/eels/Eels.htm. If possible remove both of them to another tank until your nitrite problem is solved. That way you will also have the possibility to rearrange your rocks or to install tubes as hiding spots if you like them. Cheers, Marco.>

Freshwater Moray Eels I really appreciate the time that you took for this site. <Ah, you're welcome. It was made for you.> I would like to buy a fresh water Moray Eel. I guess I need some help and no one in pet stores really know anything about freshwater. I am going to put it in a 75-100 gallon tank. What kind of sand should I put down?  <Something fine/r... and calcareous. Please see the "Marine Substrates" section and "Moray Eels" under the Marine Index (the freshwater species are touched on there)> Is possible to order a fish through the mail? <Certainly> Can I feed them gold fish? And better yet how about a book on fresh water moray. This would really help. <Not really goldfish, but other live or frozen/defrosted meaty foods. Take a look at the WWM site cited, then fishbase.org then your search engines under "Freshwater Morays"> Thanks, Michael <Be chatting my friend. Bob Fenner>

Re: Freshwater Moray Eels Thanks for getting back to me. I have called all over the place in Virginia looking for a "fresh water moray eel' I have had 0 luck! Do you know of a place that I could order one through the mail or call. <Take a look at the livestock etailers listed on our site (www.WetWebMedia.com) Links Pages> I have also had no luck looking for a book. <See the "Moray Eels" section on the WWM site> I figure that I will get a 75 gallon tank with heaters that will keep the tempter a 70-80.{F}. I will have a 2 caves in it so that it can hide and the sand that you recommended. I will buy a power filter. Do you think that I will need a skimmer? <Probably not a skimmer if you are going to try keeping the water entirely fresh... do take a look through Fishbase.org under the term "freshwater moray". Bob Fenner> Thanks again, Michael Davis

Gymnothorax polyuranodon Hi Anthony! I <Cheers my friend... and an update: THIS JUST IN: Bob Fenner was recently spotted in a quiet inlet snorkeling with what appeared to be a cluster of helium balloons tethered to his back. When asked what the deal was with the helium balloons, he claimed that he had difficulties securing proper diving gear in this remote location. However, the beer cans strewn about the boat deck and piled up against the helium tank near the tape recorder tell a different story. Look for a Christmas album from Bob this December> just bought a 'freshwater eel'. Noted in past FAQs that you have recommended addition of salt to the water so that they might survive in the long run.  <yes...depends on the species. Many are born in freshwater and venture out to the sea. As such, they really cannot be considered freshwater. Brackish is often better. Your species is actually a more freshwater tolerant animal. Still... some salt would be nice. Do read more: http://www.wetwebmedia.com/fwmorayeels.htm> But if I have Bichirs in the tank will the salt affect them? I read that they are true freshwater species. What about fire eels that are a foot long? Will the salt affect them as well? Do fire eels need salt?? <the fire ell is an "Asian" fish (Sumatra, Indochina, Thailand, etc) that prefers soft, acidic water... nothing like your Gymnothorax polyuranodon. Essentially... one of the two is going to be compromised with regard for pH, alkalinity and salinity to a lesser extent. Still... they are hardy... it may not be much of a problem. I must admit that I wouldn't mix them... but if you do not intend to try to breed them you may be just fine> I keep dwarf puffers in the tank as well. 15 of them actually. They are pretty small at the moment. I heard someone say that if these puffers are swallowed, they will actually inflate such that the aggressor will have no choice but to spit the puffer out. My concern is if the puffer makes it into the stomach and then inflates. Will it kill my eels?  <certainly, but is more likely that their toxic flesh will kill the eels first...hehe> My grouper (abt 12cm) ate one of my puffers and then looked like he wanted to puke it out... But by then he had already swallowed it. He looked pretty uncomfortable after eating the puffer... I am monitoring the situation and will let you know if the grouper makes it through the night! =P <please do> Thanks so much for your advice on medicating fire eels. You are much funnier than Bob. Hahaha... (no offense meant to Bob of course) Well I look forward to your insight once again. Thanks a bunch!! <ahhh... thank you kindly, but you haven't been around Bob enough. He has an enormous funny bone (insert your own joke here). Hehehe. Best regards, Anthony>

Re: Gymnothorax polyuranodon Hi Anthony! Thanks again for your SUPER fast response! <that's what you get when you post a question to someone that doesn't work a real job <wink>> Here are more questions... I am now in doubt as to what species my eel really is. It could be a tile, polyuranodon or rhodochilus. I'm pretty confused now. I want to keep this eel for a long time so I have noticed your recommendation for some salt to be added. However, I noted in your last msg that the polyuranodon is ok in freshwater?  <lets be clear about this... it is more tolerant of freshwater and brackish water than most morays... but it is not ideal by any stretch of the imagination... please do read Bobs articles/archives on this species> So does that mean its not necessary to add salt?  <not even close, my friend... I personally would keep this animal at 1.005-1.010 SG> What about the other 2 species I mentioned above? Do either of them have good long term prospects in freshwater? <1.005 is safe and a recommended bare minimum for the true moray eels> My eel is about a foot long and its roughly the thickness of an index finger. Its not eating yet but I just got it yesterday so...  <I won't be surprised either if it begins to do better when more salt is added. Do use a hydrometer too please> Anyway it looks pretty pale in color (pinkish/translucent) and its mottled with pretty light yellow spots. Sort of yellow... Its design looks something like your pic of the polyuranodon except that it does not have such striking color distinction. It just looks pale. Any idea which one it is? <couldn't say for certain without seeing it and even then...?> Assuming I do add salt. My tank is about 15 US gallons. Its a 2 ft tank measuring 60x30x35cm. Does that mean roughly 1 gram of salt per gallon? Your recommendations in the FAQ is one teaspoon (5gms) per 5 US gallons?  <that will get you in the ballpark, but a glass hydrometer is less than ten dollars and is quite easy to use... highly recommended> I also keep a caecilian and dwarf puffers in the tank. I think the caecilian is able to tolerate 5 gm.s per 5 gallons... Any comments? If I just put 5 gm.s for 15 gallons will it make any difference at all to my moray?  <all will tolerate the low end of the recommendation for certain> Does salt make the water more acidic or basic? <neither...unrelated> I read your site's article on salt. It says,"5.5g gm.s is sufficient for 294 gallons of water." Then the next paragraph says," For simple osmoregulatory stress protection, on an indefinite basis, one can use 1 to 3 mg/L of salt. This would be equivalent to one teaspoon of salt added to 1,453 to 484 gallons of water!" Is this contradictory or does the second Para just refer to 'SIMPLE stress protection'?  <again...you'll want to use a hydrometer and aim for 1.005 to 1.010> What's osmoregulatory stress anyways? =)  <respiratory distress...typically rapid breathing in eels that are too salty or not salty enough> This might sound like a stupid question but I'll ask anyway... If salt can distress freshwater fishes at the concentration stated above, then what happens when the salinity hits 1.010? How will this salinity adversely affect true FW fishes? <easier on the moray but harder on the spiny eels> Will fire eels be able to withstand 1.005 - 1.010?  <the lower end for sure...but not comfortably at the higher end> I assume Bichirs and dwarf puffers can but can fire eels take it? I also read that spiny eels have internal parasites? Is this harmful to them? Should I feed mine some medicine or do I just leave the internal parasites alone? <all wild fish may have them and many captive are likely as well. Do not medicate unless you need to> Do plant fertilizers affect Bichirs or eels (morays and spiny) adversely?  <unlikely in low doses> I have a huge piece of driftwood in the tank. It turns my water a very slight brown. Is this good for my eels?  <delightful for the fire eel...but not natural for the others> Do dissolved plants affect water chemistry greatly? Do dissolved plants and my wood turn the water more acidic or basic? <significantly and more acidic.> I decided to ask more direct questions 'cos I thought that it will aid you seeing as how you have such a unique way of answering everyone's questions. Hope this helps you. Thanks a bunch!!! <thank you for saying so <smile>. Do look into a local aquarium society for networking and shared info too... they really are great places for info beyond the Internet. Kindly, Anthony>

Keeping A FW Fahaka Puffer with SW Snowflake Eels  1/5/07 Hello, <Hi Hector, Pufferpunk here> First off, great source of information! I am glad I found it and I have already referred some people to it. <Fantastic!> I have a Fahaka puffer that I got when he was 2" long.  He is now 7" long. I see that he is freshwater by reading your forums. My water is kept just below 1.002 SG.  I have two snowflake eels in the same tank. My concern is for both the eels and the Fahaka. Is that SG too high for the Fahaka and or the eels?   <Below 1.002 will not affect the Fahaka but the eels need high-end BW or even better, marine conditions.> It seems he will eventually eat the eels from what I've read here.  So far he has eaten two algae eaters already but both were introduced to the tank after he was a bit larger, unlike the eels. He has been in the tank for 5 months the eels are two years old.  They had encounters when the Fahaka was small and the eels have chased him away. I have caught them laying skin to skin (freaked me out!) but they seem to have a healthy respect and equal affinity towards each other at this point. <Just don't be surprised one day, if your eels are maimed/eaten.  I'd get them in a higher salinity, without the puffer--he is a FW fish.   ~PP>   Please advise, Hector

Re: Keeping A FW Fahaka Puffer with SW Snowflake Eels. Acclimating from BW to SW  1/6/07 Great! Thanks for the response. I just set up a SW tank. You think the eels should be placed in that tank? <Only if you have cycled it 1st.  Try Bio-Spira for an instant cycle.> What is a proper way to acclimate the eels from low brackish to marine conditions? <Personally, I would cycle the tank with FW Bio-Spira & slowly raise the SG .002/week, until you have reached your desired salinity.  Otherwise, if it  is already a cycled SW tank, use a drip system. Put the fish in a bucket below the tank you will be moving it into, covered by water from the tank the eels were living in, about 1" over its head or a little deeper, so they are comfortable.  Tie a knot in an air hose until it drips enough water into the bucket to raise or lower the SG in the bucket .001/hour.  ~PP> Thanks a bunch!

Raising pH in Brackish Tank, "FW" Morays  7/11/06 Hi, <Hi John, Pufferpunk here> I am writing with a few questions for anyone who may have the time to answer them for me. All help is greatly appreciated. <I can certainly try!>    I have in my possession a "Freshwater" Moray Eel, about 14 inches in length. He is currently in a 55 gallon tank (48"x12"x18") with about 1/2" of gravel on bottom. I saw him for sale a while back and did some research on him before making the decision to purchase. The specific gravity of salt in the water is 1.008, according to my recently purchased hydrometer. <I prefer refractometers--much more accurate--hydrometers can be off as much as .005.  You might want to compare the reading on your hydrometer, with a refractometer, to see if it's true.> Ammonia, nitrite, nitrate levels are all at zero. I believe the pH is a little low for him, ranging at just over 7.5. I've had him for just over two weeks now and am having problems. :(   My first question is should I raise the ph level? <I would, BW fish prefer a pH of around 8.> He is a lone inhabitant, other than food (a few guppies ranging from very small to about an inch in length and a few ghost shrimp I put in yesterday). I'm not sure of the exact pH level he would be happiest in so I figured it wouldn't hurt to ask. Second, would he be happier if I kept him on live or switched him to frozen? I bought some frozen krill for him but he isn't taking to that very well. If it's better for him to be on frozen, what is the best way to switch him to frozen? One person I talked to said that I should not let him eat one day, then try frozen the next and if he doesn't take to it then give him some fresh and to just keep trying that making the gaps in-between feedings longer, until he breaks and eats the frozen krill. <You will have to "train" him to eat frozen foods (hopefully you are defrosting before feeding).  You can spear the food with a wooden stick (like the ones they use for kabobs) or you can get a plastic one at your LFS.  I'd take away his live food for about 3 days before trying this.  Then you will have to entice him, by wiggling the food around by his face (preferably in the evening, during "regular" hunting hours).  You could also bounce the food off a thread (use a needle to go through the food) but don't tie a knot in the end.  I would try a variety of foods, including silversides, people shrimp & any other odds & ends you see for sale in your grocery/produce store.> My other problem is with his breathing. He is breathing rapidly with the same symptoms of another eel I read about in one of the FAQs on your site but I don't believe that low salt is the problem. Like I said the salt level is at 1.008 SG. What else could possibly cause this breathing problem? He is not eating as much now as he used to. Is it because I'm trying to switch him to frozen or because he is sick? He is displaying no outward signs of any parasitic infestation or bacterial infection. Is there the possibility of internal infection? <Heavy breathing can be a sign of ammonia/nitrite issues, affecting the 02 levels in the water and/or burning their gills.  How long has that tank been set up?  Are you doing regular weekly water changes?  You should be seeing some detectable nitrates in a cycled BW tank.  How was the tank cycled?  How quickly did you raise the SG?  It should be only raised by .002/weekly water changes so as not I'd test the water again.> My last question is due to fact that he is a brackish water fish. Could I put substrate at the bottom of his tank instead of the standard fish gravel that he is in now? <This actually goes back to your pH question & how to raise it & keep it stable around 8.  It is recommended to use crushed coral or aragonite as substrate in a BW tank.  Since you only have 1/2" of gravel in there, you could just add another inch to that.  If your gravel is dark though, you may not like the look & want to change it out completely for the buffering substrate.> He seems to be doing just fine with the gravel--he is burrowing down under some rock I have in his tank during the day.  Kind of like a natural rock structure that he swims through and sleeps under. <Yes, they hang out in burrows during the day & hunt at night.> I have some knowledge about aquariums but I don't know everything <Ha, me either!> and hopefully you guys can help me learn a little more about this guy. I've had him for just over three weeks now. Anything you guys can share is greatly appreciated. Thanks for your time and have a great day. John R. Ayer <Thanks John I will (today's water change day) & enjoy this interesting creature!  ~PP>

Re: moray growth cycles   7/18/06 Thank you for your quick response. I have read that morays can live over 30 years. <Yes, there are public aquarium records of this and longer lifespans> Based on your information and my observations, I am almost certain my albino will have no problem making it over a year and would not be surprised to have him around for a long time. When I first got the snowflake he went right into hiding and did not venture out for a week. My albino would not go into this area while it was hiding <Muraenids are by and large non-social species... Don't associate with conspecifics or other members of their family> and only my leopard bushfish and butterfly goby would go into the area with him. After he finally ventured out my albino went back into the area but so far the snowflake has been staying out and not even trying to hide except when the lights are turned on abruptly. For the week during the snowflakes hiding period the albino seemed like it did not bother him he seemed so easy going and seems not to let stress get to him. I have had the albino now almost 6 months but only about 8 days for the snowflake. If the snowflake can settle down like the albino he may live a long time too. The main factor is now they are in a 10 gallon tank <Way too small...> with plans to get a 125 gallon in the near future but may get a 55 first then transfer to the 125. I have other fish that I will eventually need a 55 for that are freshwater only. I appreciate your help. <Welcome. Keep monitoring your water quality, and keep that lid tight! Bob Fenner>

<Ongoing: brackish to marine> albino moray in a larger system... Still not reading... and raising RMF's BP   7/24/06 I have written you before on my albino moray believed to be of the species that I currently have in a 10 gallon tank. I would like to know if a 30 gallon tank would be large enough for him? <... have you read where you've been repeatedly referred to?> A friend said he would give me one since he was getting out of freshwater and getting into saltwater system with a larger tank. I did not know if I should put my eel in it or take my bichir and friends in it. So far my moray has never tried to escape and I have had him for a while with no lid on my tank. When he is at the top of the tank he is either hanging off the thermometer and ammonia sensor or laying on top the heater trying to catch guppies. His length is from the top of the gravel his head comes just under the black trimming of the tank on top. I so far like the idea of his eating live food and according to information I have read he will remain small enough to continue eating ghost shrimp and guppies based on the assumption his species is correct he will not get much larger than he is now. <Will most likely be dead soon> One last note about nitrite levels you said they should be 0 and I had said they were very low. I was going by what the test by Tetra gave me a match at less than 0.3 mg/l. Is this a good reliable test? <Mmm, middling> I have a rather unusual final question regarding filtration. Would using the filter that came with a whole set up like a 55 along with a small bio wheel that was for 20 gallons be of any help or would I be better off getting a bio wheel for that size alone? <Bigger is better> With a moray involved I do not feel comfortable with a standard filter alone. Thank you very much I want this albino to be as happy as he can be and so far my experiences with this one has all been positive. He seems so inquisitive and easy going. <Please... read: http://wetwebmedia.com/FWSubWebIndex/fwmorayeels.htm and the linked files above. RMF> Info about Gymnothorax tile eel   2/10/06 Greetings, <Salutations> I have a Gymnothorax tile eel AKA (Freshwater Snowflake Eel) and I have questions concerning his well being. Right now he lives in my 45gal Brackish water tank and seems to be doing quite well. I have had him for nearly 8 months and he is currently on a diet of squid. <Need to expand this diet> However I did some research on him and several articles say that this species does better in a marine type environment. <Some do... with size/growth> Is this true? Second most of my research says that this particular species can survive in a brackish environment but not for long term. I currently have a 65gal saltwater tank that I am currently establishing that at this moment has no fish or animals of any sort. My question to you is this, would my Gymnothorax tile eel do better in a marine type environment or can I leave him in his current brackish water home? <Would be better in all marine> Second, if I were to transfer him to my marine aquarium can you recommend a procedure to minimize the stress on the animal? <Matching present spg, increasing some 0.001 to 0.002 density per week by adding/changing out water of increasing saltiness> I have done a lot of research on this animal but it is hard to separate fact from fiction. I would hate to loose him due to my ignorance. Many thanks in advanced Mike Hoefnael <Welcome. Bob Fenner>  

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