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FAQs about Morays Eel Sex, Reproduction

Related FAQs:  Moray Eels 1, Moray Eels 2, Moray Identification, Moray Selection, Moray Behavior, Moray Compatibility, Moray Systems, Moray Feeding, Moray Disease, Zebra Moray Eels, Snowflake Morays, Freshwater Moray Eels, Other Marine Eels,

Related Articles: Moray Eels, Zebra Morays, Snowflake Morays, Ribbon Morays, The "Freshwater" Moray Eels, Freshwater Moray Eels by Marco Lichtenberger, Other Marine Eels

Eggs???    4/5/20
So guys we were having a nice fun experience at the store today these randomly showed up and started floating all over the system didn’t know if you have any rough idea on what it could be
<Interesting... DO look like eggs of some sort... are your systems separately re/circulated? What sort of livestock is in this tank? Can you give me/us some idea of the objects size? Bob Fenner>

Re: Eggs???    4/5/20
Yep not a problem so the livestock is actually very limited in this aquarium it is a 500 gallon with a 125 gallon refugium
Total livestock is a 3to 4 inch red leg hermit
One 8 inch Sailfin tang
2 yellow tangs 1 3-4” 2 6”
<Mmm, too small to breed...>
2 yellow stag horn damsel was not able to find any nest location and one is only about 1 inch in size
One Hawaii zebra moray 28 inches
2 Hawaii dragon Morey have been in the system for about five Hawaii Dragon moray have been in the system for about five years now both 28-32”
<Maybe some organism in the (live) rock, or refugium... I'd put some in a floating, all plastic fine meshed net and see what they hatch out as! BobF>
Re: Eggs???    4/5/20

We were thinking the dragons as it was coming from the general area that the larger “female” was siting having some labored breathing
<Oh, wow~! That would be incredible. Am going to ask Marco here (our muraenid expert) to comment. Bob Fenner>
Re: Eggs???    4/5/20

<Would be great. Had a look at the pics. Cannot exclude that they are eel eggs, cannot confirm either. The fertile moray eel eggs I've seen had a clearly visible embryonic larvae, so maybe they are not
fertilized. As Bob suggested, put them in a net and observe if they change and how. Moray eels become significantly obese when carrying eggs (like at least 1,5 their normal diameter) and this quickly goes back to normal once the eggs are laid. You can take this as an hard to miss indicator for if those are really eel eggs. Also, have a look here to compare:
(there was also a case in a zoo in Germany in 2002 if I remember correct). If you wish keep us updated. Cheers, Marco.>
<Ahh, thank you Marco. Will forward any updates your way. BobF>

Regarding Morays     1/23/20
I would very much appreciate the opportunity to correspond with someone who  has a lot of experience with morays.
<I have some practical (husbandry) with a dozen or so species, years of collecting them for the ornamental trade, and MarcoL here has much more; written a book (en Deutschen). Send your questions, observations on. Bob Fenner>
Re: Regarding Morays; sex beh.; repro. f'      1/24/20

<Hi Hannah!>
Have you ever noticed any physical change gone through by any of the morays
that might indicate a change in sex?
<Yes, definitely with E. nebulosa: The change from female to male is accompanied by a change of their teeth (there are more species like this).
Males of this species are generally larger, have longer, slightly hooked and serrated teeth in the front of their jaws and may become fish eaters instead of crustacean eaters. Also with Rhinomuraena quaesita: their change from male to female (the only moray species known so far that changes this way) is accompanied by a color change from blue to orange. At least in nature, in captivity this does not work every time.>
Also, have you ever gotten the morays to spawn?
<You'll find quite some reports of morays producing eggs in aquariums as well as documented spawnings in nature, but real spawning in a tank? The only documented spawning in captivity that produced fertilized eggs I know of happened in the Vivarium Karlsruhe with R. quaesita. The planktonic
larvae could not be raised as far as I know.>
If so, was there any event such as a change in water parameters, day-night cycles, etc. that caused the spawn?
<There probably was, but there is no definite indication what exactly did cause the spawn to my knowledge. In nature lunar phases and seasons are suspects.>
Assuming morays are not able to change their sex, have you ever noticed any physical trait that varies between individual morays that could be a sex based trait (such as jaw shape).
<This differs very much within the family. Some morays change their sex (sequential hermaphrodites) such as E. nebulosa, G. fimbriatus, G. zebra or R. quaesita, while most morays don't change their sex and a few are even simultaneous hermaphrodites (they can act as female and male, e.g. G. griseus, G. pictus). There is a lot of additional speculation on how to sex morays in the hobby, most of it totally unsubstantiated by science proper (examination of the gonads). Jaw shape does not indicate sex to my
knowledge, but dentition does in some species (see E. nebulosa as an example above) and coloration does in R. quaesita.>
<Hope this helps. Cheers, Marco.>
Re: Regarding Morays    1/27/20

Thank you for all this. Do you know what triggers the change in sex in those species that do change?
Is it once they reach a certain weight (which I find is often how it is with fish that go from female to male, so this is something I’ve hypothesized).
<The exact trigger is unknown (Have a good read here: https://www.karger.com/Article/Fulltext/449297 ). My best guess for moray eels is that it's age as well as the environment, specifically hormones of other fishes of the same species, which can delay a change in sex. Weight and muscle mass do influence such hormone induced processes (similar as human puberty is influenced by them), but are not necessarily the major trigger, which is indicated by the overlapping size distribution of the two sexes.>
And how long does the transition take, and how obvious are the differences?
<From my own limited observations this is a rather quick process, around two or three months on E. nebulosa, M. pavonina and R. quaesita. How obious it is depends on the species. In my opinion it is well visible on the teeth of E. nebulosa and other species with sexual dimorphic dentition once you have seen it. The color change of R. quaesita is also very striking. For M. pavonina it was less obvious in morphology and remains rather speculative.>
The reason I brought up jaw shape is because in my observation of many descriptions of G. melatremus, I’ve noticed that some larger ones also have a more developed lower jaw, which I’ve noticed can be an indicator of a change in sex in many fish species. Of course this is all anecdotal.
<G. melatremus is considered to change from female to male (protogynous hermaphrodite) in Michael's Reef Fishes vol. 1 without going into detail. This classification is spread online, because the book is very popular (it's a great book). On the other hand, L. Fishelson, who investigated sex change in morays in 1992, examined the gonads of 5 G. melatremus specimens and did not list this species as possible protogynous hermaphrodite. So, I don't think G. melatremus does change sex. Of course, I cannot exclude that a more developed lower jaw can be an indicator of sex (it does not even need to occur in relation to a sex change, could be simply reaching sexual maturity). It can also be related to bone growth because of the high stress this structure endures (you'll often see malformed, broken and healed lower jaws on morays. I believe this is the most damaged bone in this family). As long as no one has looked at a possible correlation of the gonads and jaw development, we simply do not know. Cheers, Marco.>

Chain Moray prep   1/12/06 Hey crew! I've done quite some research and unfortunately, I haven't found much info pertaining to the care and habitat of Echidna catenata < http://fishbase.org/Summary/speciesSummary.php?ID=2609&genusname=Echidna&speciesname=catenata> or the chain moray. <A delightful small Muraenid aquarium species... just not often collected/used... I have only seen it in the wild on a few occasions... much less common than its congener E. nebulosa in the Pacific> Most of what I found is pretty much set in stone for the eels (tight fitting lid, lots of live rock, protein skimmer, etc...). So I just wanted to confirm some things on this particular fish. Does its diet include mainly other fish or crustaceans? <Almost exclusively the latter, but some small fishes as well> And from what I've gathered it requires a 125 gallon aquarium for an individual. Does that sound right? <Yes> And lastly has it been successfully bred in captivity? <As far as I'm aware, no Moray species has been bred, reared in captivity> Hope you can answer these questions and thanks a lot                     Kev <Welcome. Bob Fenner>

Zebra Moray Eel Eggs  - 09/14/06 HELP! My Female Zebra Moray Eel had eggs (TONS of them) last night!! I netted out a lot of them and put them in a 10 gallon tank. I know they will hatch in about 4 days and be in the planktonic stage - but what do I feed them then to try to keep them alive?? I know it will be 6-10 months before they look like eels and that is why most do not make it. PLEASE any help you can give would be GREATLY appreciated. Thanks, Christin (I also took pictures and videoed her having babies) <... let's back up a bit... You only have one Gymnomuraena specimen? These eggs will be infertile. Bob Fenner>

Re: Zebra Moray Eel Eggs  - 09/14/06 Bob Fenner, <CC>      No sir, I have 2 of them. They are both about 2 1/2 feet long. <! Bonus!>      The eggs seem to be still doing well, none have hatched as of yet.      I did get small fry (liquid) and Kent ZooPlex to "feed" them when they hatch. I don't know if this is correct - Please let me know. I would love for them all to make it. Thank you in advance, Christin Cross <I do wish I knew more to relate here... There is some scientific literature... I'll look for Ron Thresher's volume here... re Muraenid reproduction, larval development. Best of wishes for your success here. Bob Fenner>

Re: Zebra Moray Eel Eggs  10/03/06 Bob,      I just have another question for you, I thought none of my Zebra Moray Eel eggs hatched so I was cleaning out the tank. But, I found 2 "worm like" things on the bottom. I scooped them out and finished cleaning out the tank and put them back in (by themselves). I have attached pictures, are these baby eels???? Thank you, Christin Cross <Mmm, no pix attached... Most likely (highly) these are worms of some sort... True Eels/Anquilliforms have long pelagic larval histories... not going to metamorphose, settle in an aquarium. BobF>

Zebra Moray Eel I have two Zebra Moray Eels and one is black with white stripes and the other is white with black stripes. How Do I determine the male from the female is there a specific marking or etc. <I have never heard of Zebra morays being sexually dichromatic.  Are they different sizes?  Usually juveniles have thicker white stripes compared to the adults.  Full grown ones will have very thin white stripes on a dark brown base.> Moray eel parental care Hi. My son is working on a research project about moray eels. Does anyone know how they care for its young? thanks a lot <Mmmm, no parental care... gametes are released into the water column following a bit of a "prenuptial dance"... where if fertilized, not-consumed, the young go through a few weeks pelagic metamorphosis... on their own... and with luck drift to, settle to a suitable area. Bob Fenner>

Snowflake Romance Hi <Hi, Mike D here> I was wondering if you know anything about Snowflake eel reproduction?<Not as much as I wish I did. I've been told that Snowflakes are protogynous hermaphrodites that change sex as they go through various stages of their life, much like groupers and wrasses.> I have a Snowy who has become rather active,  before I was lucky to see him, but now he swims in and out of the rocks apparently looking for some thing.<This behavior seems to be related to growth and security more than sex, with larger animals having more self confidence in their ability to take care of themselves, particularly in familiar surroundings.> He is eating and looks fine and I have had him for over 2 years now.<The age would seem to indicate that it's at or approaching sexual maturity.> Is there any chance he is looking for a mate? It is spring here in Australia.<That's always a possibility as spawning urges are often triggered by the length of the daylight hours.  It's quite likely that the presence of another, older Snowflake would be the final factor involved, but if they are like many other eels the probability of captive rearing is extremely remote due to their complicated and extended juvenile stages.> Cheers Jess

Gymnothorax melatremus and Gymnothorax miliaris Hello, <Hi there> My question pertains to the sexing of these to eels.  I currently have one of each and would like to buy another of each.  Is there anyway to tell the difference in sex so that I might be able to buy the opposite for a possible pairing? <No dichromic or dimorphic (color or structural) sexual differences that can be appreciated externally... as far as I know> Both are fairly docile eels, relatively speaking, so I'm not concerned about adding the same sex but I would like to avoid it. Also, is there any documented marine eel breeding in captivity that you are aware of?  If so, could you elaborate? <See Ronald Thresher here as well as the Tesch review posted on WWM. Bob Fenner> Appreciate your help, Chris

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