Freshwater Morays Exist?

[Marine/Freshwater?]

I'd really like to post this under the pinned topic section. If somebody could put it there or tell me how to put it there it would be greatly appreciated. Also feel free to make suggestions.


There are many true eels that aren’t restricted to saltwater environments . Some are only tolerant of freshwater. However the commonly offered "spiny eels" are not true eels at all. One of the major red flags that proves you don’t have a true eel is the presence of gill flaps or the absence of protruding nostrils . If you are curious about whether or not your pet eel is tolerant of freshwater check it out on fishbase.org . Fishbase.org is a great site for information about the classification of fish. In this thread I will include information on several commonly encountered eels, and some other eel like fish that occasionally turn up in brackish aquaria.

First of all you need to understand the taxonomy of the order Anguilliformes in order to determine the salinity requirements of the different species of eels you will encounter as an aquarist. Anguilliformes is the order of all true eels . Under the order, classification wise is the family. There are 15 families of true eels. Some that you might be familiar with include Snake eels, Moray eels, Spaghetti eels and of course the Freshwater eels. There is an entire family of eels called freshwater eels that look similar to conger eels that live in freshwater and spawn in saltwater. All of the eels in that family can be found in freshwater. In addition there are many species freshwater and brackish eels in other eel families. For example, Gynothorax Tile (commonly called the Freshwater moray, really brackish though.), Strophidon sathete (Gangentic River Moray.), Pisodonophis boro (Rice Paddy Snake eel, freshwater,brackish,marine).

Below are several species of brackish eels available that I think are worth mentioning:

HARDY,HUNGRY (Gymnothorax tile) Freshwater Moray- Often mislabeled as Gymnothorax polyuradon. This is dusky tan to brown colored eel that is covered with metallic gold flecks. It is the most commonly sold "Freshwater Moray". It in fact requires a salinity of 1.010+ to live a long healthy life. It can live for 15+years and grow to at least 36" or 90cm. when properly cared for.

SUPER RARE (Gymnothorax polyuradon) River Moray- An extremely rare moray Gymnothorax polyuradon is yellow or white with large black spots that resemble a leopard. This species is said to be much less hardy than Gymnothorax tile. This is why it is less likely to survive transport. However hypothetically (if anyone could actually keep it alive) would tolerate freshwater. Being on the safe side the salinity that they could be kept at should be near 1.005 but no higher than 1.018. Only known to reach 24" or 60 cm.

DOESN'T EAT OTHER FISH (Echidna leucotaenia) White Face Moray- I often see pictures of this fish labeled as Echidna rhodochilus. Echidna rhodochilus is known as the Pink Lipped Moray. This eel resembles the marine Snowflake Moray (Echidna nebulosa) in shape and acts similarly. It is an overall burgundy or brown with white marks on its lips. This is not as easy to care for as Gymnothorax tile, but an advantage is it will likely ignore fish. It only eats crustaceans. It needs a salinity of at least 1.010 and appreciates marine conditions. It grows to 18" or 75cm.

VERY FRAGILE (Uropterygius concolor) Ghost Eel, Unicolor Snake Moray, Ghost Ribbon Eel- Rarely encountered as a marine fish. It is a shimmer silver color with a white edged dorsal fin. It also appears to have black dots on its face. This is a very petite slender eel. It is often sold in a saltwater settling, however it can be kept at salinities as low as 1.015. Acclimate it slowly to high end brackish. Warning: it can be easily confused with several saltwater only look alikes. These include: (Gymnothorax albimarginatus) White Margin Moray, (Gymnothorax phasmatodes) Ghost Moray, (Pseudechidna brummeri) White-ribbon Eel.

Non-eels for brackish aquaria-

(Mastacembelus sp.) Spiny Eels- Very good fishes to keep. No real complaints about spiny eels just don’t trust them with small fish, also get a tight fitting cover. They seem to have a suicidal fixation with the garbage disposal. Apparently likes to jump. One of my friends used to have a Fire eel that would end up in the garbage disposal once a month until he moved his tank off of the kitchen counter. Spiny eels don't really belong in brackish aquaria. They do tolerate a higher P.H., 8.0 and seem to appreciate small amounts of salt but anything over 1.005 would be damaging. Spiny eels do not and will never belong in the same tank as a Freshwater Moray. Totally different water parameters.



NOT AN EEL BUT IS QUITE HARDY (Congrogadus subducens) Green Wolf Eel-really a Pseudochromiod (dottyback). Salinity between 1.010-marine. Good choice for beginners but really bad about eating its neighbors. Good match for medium and large Gymnothorax tile, not babies though.

EVIL, KEEP ISOLATED, WIEGHT DOWN COVER Swamp eel- One fish I really hate, but I would recommend it for those who will keep it alone. They look similar to morays but they have gill flaps. They are often a molted brown color like a really sick Freshwater Moray. They are always getting sold at my LFS as Freshwater Morays. They are Really, Really, Really , Really , Really , Really Mean! It bit me when it was taking it out of the bag and putting it in my fish tank. Then it KILLED all my fish, it was very aggressive it bit anything that moved it did not even eat anything it killed. It bit fish that were twice the size of it head and taste tested anything that moved. I was glad I kept the receipt. Swamp eels would make great pets, but keep them by themselves in a large tank. Most species can’t tolerate saltwater. They are very hardy and strong. They even have auxiliary breathing organs. Be sure to weight down the cover they love to take long walks in the park. Don’t use your Algebra book though. I had to explain to the bookkeeper how my fish knocked my book in the tank. WARNING: some species get huge!

GOOD EATER (Plotosus lineatus )Striped Eel Catfish does not look that much like an eel but I like it. Black with horizontal white stripes. WARNING it has some pretty lethal venom on its dorsal spines so watch out, they really do hurt. It can live in water with a salinity no lower than 1.015. It is able to tolerate freshwater as an adult but a salinity of 1.015 would be good long term. You can find more about this fishes feeding, and habits elsewhere.

In closing I must say don't ever trust what pet shops say! Google or better yet look the fish species up on Fishbase.org. Do not be intimidated into buying a fish that you are not familiar with.

 

[pica_nuttalli]

Ok, I know that you mean well and I'm sure that this information is great, but the formatting approach that you use makes it highly unreadable. I would suggest moving away from the paragraph form and using bullet points to organize the fish information. Also, I find the random bold-face to be very distracting and would suggest that it be reserved for emphasis of phrases only.

 

[andywg]

Considering G. polyuranadon lives its entire life in FW in the wild, I don't think saying it will "tolerate" FW is using the best verb.

Also, your description of Uropterygius concolor as white and silver makes it sound very much like Pseudechidna brummeri (which I have one of). Fishbase (which you value so highly) states that U. concolor is "drab brown" in colour with a yellow tip to the tail.

I also echo pica's points regarding formatting. Random smilies have no place in an authoritative piece of writing, nor do random bold print.

 

[severum boy]

Considering a couple of people I know and one person on this forums keeps Gymnothorax polyuradon and it isent dead, Id say they were cirtanly possible to keep, the real difficulty lies in actually finding one. Also, I dont think anyone has raised a Gymnothorax tile 90cm, 60 seems to be the norm.
Also, I trust most of what pet shops say. I aviod cirtain retailers and go to ones that I do trust. It is foolish to say that pet shops are untrustworthy, when only a minoritory are.
Also, why would you say Spiny eels can be kept in brackish water, then later completely contradict yourself?

 

[Tommo]

All the smileys and bold writing make this very difficult to read, also many people on this forum, including myself, work in pet shops. Does that make us all untrustworthy?

 

[CFC]

I already posted a similar topic covering all the basics in January 2005, its in the guide to oddballs pinned topic (actually i really should write a bit more of that and get some others involved for bits of it)

Eels

There are 3 main families of eels that fish keepers may come across in fish stores, these are the spiney eels of the Mastacembelus, Macrognathus and Aetiomastacembelus genuses; The moray eels of the Gymnothorax and Echidna genuses and the swamp eels of the Synobranchus, Ophisternon and Monopterus genuses. Of these only a handfull of species are suitable for the average fish keeper and some have specialist needs.

Spiney eels

There are 3 main species of spiney eel commonly sold in fish stores and two that may be found in more specialist stores, these are.

Macrognathus siamensis(aculeatus), Peacock spiney eel; The smallest of the commonly seen spiney eels, this species will only reach a captive size of around 10 inches and is suitable for communities in tanks over 30 gallons with tankmates over 2".

Mastacembelus erythrotaenia, Fire eel; The fire eel is the second largest of the commonly seen spiney eels and can reach lengths of up to 30 inches though 2 feet is more likely in captivity. They are predators and will consume any smaller fish that they can fit into their mouths so tankmates should be over 4 inches. A tank of 180 gallons is needed to house adult fish though the species grows quite slowly.

Mastacembelus armatus, Tyre track eel; Tyre track eels are the largest of the commonly seen spiney eels and can reach lengths of up 40 inches, as with fire eels they are predators and will eat smaller fish. A 180 gallon tank is needed to house adult fish.

Macrognathus zebrinusZebra eel; The smallest of the imported spiney eels but unfortunately the species least often seen, zebra spiney eels rarely reach more than 8 inches in captivity and are the perfect community eel as even small fish such as tetras are ignored.

Aethiomastacembemus ellipsifer; The most commonly imported of the rarely seen African spiney eels. The species is only found in Lake Tanganyika and so needs to be kept in hard alkeline water, a great addition to the tank of the Tanganyikian Cichlid enthusiast.

Other African spiney eels you may be likely to come across are Aethiomastacembelus moorii and Aethiomastacembelus plagiostomus[/i. All African spiney eels are predatory and tankmates should be at least 3 inches.


"freshwater" Moray Eels

Firstly it should be said that there is no such fish as a freshwater moray eel, all members of the Muraenidae family require some salt in the water they are kept in with most species requiring full sea water to survive. There are 4 imported species of so called "freshwater" moray eels which are naturally found brackish waters of which 3 can be found in fish stores with some regularity with the fourth being extreemly rare.

Gymnothorax tile, Snowflake moray; Easily the most commonly seen of the FW morays G.tile can be found in two colour morphs, the common "snowflake" pattern which is black with white spotting and the slightly less common "goldspot" which is black with gold spotting. This eel will require the SG of the water to be atleast 1.005 and this should be raised as the fish grows, in the wild mature fishes are found in full seawater. The fishes appetite is directly linked to the level of the salt in the water and those kept in freshwater may starve to death. G.tile can grow to as much as 2 feet in captivity and as with all moray eels is a voracious predator so tankmates should be large and robust.

Echidna rhodocheilus, White cheeked moray; Not as common as G.tile but sometimes found in more specialist stores E.rhodocheilus can easily be identified from other morays by the two white patches either side of the jaw from which it draws its name. It is the smallest of the FW morays with a adult size of around 18 inches but is quite delicate and can be difficult to keep, the SG of the water should be kept at atleast 1.010 and the use of a protein skimmer is recomended. Eels of the genus Echidna do not prey on fish as much as those of Gymnothorax and are primarily crustacean eaters.

Gymnothorax afer; Sometimes accidently imported with shipments of G.tile but easily told apart by the lack of any spotting on the body. G.afer can grow to 40 inches so needs a fairly large tank but is otherwise identical to Gymnothorax tile

Gymnothorax polyuranodon, Leopard moray; A very rare fish in the trade G.polyuranodon is almost never imported which is a shame as it is the prettiest of the 4 FW species, is reported to reach around 30 inches but almost nothing is known about keeping this fish in captivity.


Swamp Eels

Swamp eels have recently started to become more common in the more specialised shops where they are sold as "tulip eels", small specimins may catch the eye of the oddball enthusiast but these small interesting eels quickly grow into large predatory monsters and only the dedicated fish keeper with a large tank free to use as a species tank is able to house them. There are 3 species imported which are listed below.

Synbranchus marmoratus, Marbled swamp eel; The most commonly imported of the swamp eels this species will quickly grow to around 3 feet in captivity and is a formidable predator, adults should only be kept in a species tank. The jaws are powerful enough to do considerable damage to the unwary owners hands!

Monopterus albus, Asian swamp eel; While not reaching the same size as its American cousin S.mamoratus the Asian swamp eel is still a large and very predatory fish, captive adults top out at around 2 feet and should be kept in a species tank.

Ophisternon infernale, Blind swamp eel; Not as comonly imported and almost identical in appearance and size to M.albus, as with other swamp eels a species tank is recommended.

Other eels

Other eels that may occasionally be seen are the European eel Anguila anguila and other members of the Anguila family and the electric eel Electrophorus electricus which is not an eel at all but a knife fish, these should be avoided due to size and in the case of the electric eel the potential danger of electrocution.