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Yellow headed Jawfish; repro. 4/29/14
Hi Bob, I was hoping that you can help me, I have a pair of yellow headed Jawfish, the male regularly carries eggs, he will tend to leave them in the burrow and come out for feeding but today he hasn't, it is almost like the
female is blocking his burrow! Can this be normal and will he start feeding again?
<Is normal and he will recommence feeding... Are you planning on trying to rear the young? What foods? Bob Fenner>
Re: Yellow headed Jawfish 4/29/14
Thank-you, I was getting a bit concerned, you have put my mind at ease.
I am looking at rearing the young when I have mastered culturing rotifers and brine shrimp!
have you any advise on raising the young? your help is appreciated.
<Just what is posted on WWM. Cheers, BobF>
Re: Yellow headed Jawfish 4/29/14
<Pleasure Lorna. B>
Jawfish and Foxface; comp. 2/1/14
Sexing a dead yellowhead Jawfish... 9/22/11
Opistognathus aurifrons breeding... sys., fdg...
A source for Brachionus rotundiformis for feeding pearly
Jawfish larvae. - 10/06/2009
Wife swapping Jawfish 10/14/08 Hey Crew, So there are some strange goings on in my biotope. I lost one of my female Pearly Jawfish 2 weeks ago (I believe due to her mate not letting her out of the burrow to feed). I now have 1 female and 3 males, and the female is in a different burrow every few hours! She's pretty assertive, nipping at the males tails if they try to keep her penned in, as she like to be roving the entire aquarium as much as possible. I've been looking, but have yet to find anything about this sort of behavior, more that they are pretty monogamous fish as long as their mate is alive. Ever heard of this sort of "wife swapping"/Jawfish Stud farm sort of thing? -Darby <Hello Darby. Jawfish (Opistognathidae) can be polygamous in the wild, given the chance at least, although usually described as monogamous fish. Do see "Monogamy in marine fishes", Whiteman and Cote 2004 for an overall review of monogamy/polygamy in small marine fish. It's actually pretty common for fish to switch between breeding modes depending on the circumstances, and arguably happens even supposedly monogamous animals such as humans! If one or other partner can get away with "spreading its genes", it will. Since the female doesn't brood the eggs, the male does, she can get away with (and evolution will likely favour) mating with multiple males. It's an insurance policy that means that even if some of her mates are hopeless fathers, at least some of them will be better. If she (literally!) puts all her eggs in one basket -- i.e., mates with just one male -- she's gambling everything on that male being a skilful father. This behaviour is constrained by environmental factors. For example, if both parents must work together to defend the eggs/fry, each parent is less likely to philander. But that isn't the case here, because male Jawfish have their own burrows and incubate the eggs alone. Among cichlids, many species form monogamous pairs in aquaria when forced to do so, but are polygamous in the wild (Kribs are the classic example). So in your situation, you've got a tank where the female is able to choose from multiple males, and is taking full advantage of the situation. Cheers, Neale.>
Yellowhead Jawfish stkg. 12/27/07 Dear Crew, Thank you for all the help you have I given me in the past. You don't know how much you have helped me. Unfortunately a new problem arises. I have been interested in Opistognathus aurifrons for some time now and have been planning to convert my 55 gallon freshwater tank into a saltwater tank for the soul purpose of keeping these Jawfish. My question is if I kept nothing but Jawfish and some liverock in this tank could I fit four? <Mmm, possibly... but all would be happier/better with just two or three...> The reason I would like four is because I would Like to obtain a pair for breeding purposes. Any suggestions? Thanks, Tuscan Thompson <Take a bit of time reading accounts of Jawfish spawning, aquaculture... Maybe start at the Breeders Registry (.com). Bob Fenner>
Jawfish and Pod QT! 4/27/07 You have a fantastic site and very worthy of the days (yes, days) I've spent reading during the past couple months since starting a 55 gallon SW tank. <Thank you.> My setup is: 5-7" DSB, 60# LR, 360gph canister (bio-balls removed), <Good'¦> two powerheads, SeaClone 100 skimmer, <not my first choice, or second. third'¦but better than nothing.> 130w PC 50/50 actinic & 10k daylight; and water data is: PH 8.2; Ammonia & Nitrite 0; Nitrate 7.5; Salinity 1.025; Alk 13dKh & Calcium 375. Inhabitants include 2 Percula clowns, 3 Chromis, 2 damsels (going back to the store as soon as I catch them), <Also Good.> 2 BTAs, <Clones of each other I hope?> several hermit crabs, feather dusters, various snails, mushrooms, Zoas & a couple leather frags. All seem to be doing well, better now since I caught & took 2 very ornery damsels back to the store. <Sounds functional.> I have a 10 gallon quarantine tank that has sand and shells on the bottom for two Jawfish I just ordered. <Neat.> I have wanted these since I started the tank; also the main reason for the DSB in the display, although after research here, the DSB is worth much more than just a substrate for the Jawfish! <Yes.> A couple of quick questions on the Jawfish - are they hermaphroditic? <As far as I know, they aren't. Breeding behavior is different depending on the species. You can usually distinguish the male of a pair during mating events by their more distinguished markings and color. To my knowledge there have been a few successful breeding reports but almost all seen in the trade are still wild caught.> I'm guessing that they are not, but was curious & haven't been able to locate that specific info. And I understand that the Jawfish need some shells for structure of their burrows -- <'¦Don't count out vanity,,,, yes fish can be arrogant too.> do I just put in a couple handfuls of crushed shells in a few places on top of the sand where I would prefer that they burrow? <Just place them randomly around the tank, they will put them where they want them'¦and may occasionally steal shells from each other as well'¦.which as long as no one gets hurt is actually fin to watch.> I also ordered a group of copepods, and am wondering about a quarantine procedure for them. <Most people forgo it, but there is no 'standardized' way to do it really'¦> I'm trying to go forward with the "quarantine everything" adage, <Good!> but when I previously purchased some copepods for the display tank, the instructions were to add the entire contents of the bag directly to the tank, water and all (which I did with no ill effects). <You don't mention which company you are getting them from, but typically the reputable folks who market these are very meticulous with their products. Keeping the strains pure'¦.literally down to a 'science', hehehe. There aren't (again typically) any pathogens or micro-organisms that would be a threat to your fish.> The new copepods are planned for the 20 gallon refugium I am setting up, which is not attached to the display tank yet. <Perfect, if the fuge is offline, go ahead and add the 'pods directly to the fuge, and wait a week or two before plumbing it inline'¦.if you have the space/ability to do so.> I plan to put refugium mud as a substrate covered with crushed coral, with red mangroves for nutrient export. <Mangroves are rather poor in comparison to other organisms when it comes to nutrient export, read this by Mr. Calfo: http://reefkeeping.com/issues/2004-12/ac/feature/index.htm .> I have planned on hooking up the refugium to the display tank as soon as I get it put together in order to let the display tank cycle it. I understand (from reading here) that there are different opinions about whether the refugium should be cycled separately, but since I didn't plan to add any bioload right away, I figured it would be okay to add the refugium to the display as soon as it is set up. <I did this, had to compensate with extra water changes. It should also be noted I precured the rock in a separate container though.> However, if I need to quarantine the pods, I would need to do that in the refugium area before I hook to the main tank, and probably before adding the substrate, right? <Yes, as I mentioned above that would be a good way to go'¦'¦it will also give the pods sometime alone (without being preyed on) to populate the refugium.> The big question is: Do I need to quarantine the copepods, <Probably not, but it wouldn't hurt.> & if so, what is the procedure? <See above.> Thanks for all your help. <Anytime.> Lillian <Adam J.>
Jaw Fish Breeding Hi Bob, <Anthony Calfo, here in your service> As many others have said, the Conscientious Marine Aquarist, was the first in our marine library. It gave us a good start, and continues to answer our questions along with WetWebMedia. Thanks! <an important and must-have reference, indeed!> We have three yellow tail damsels (Chrysiptera parasema) and two yellow head jaw fish (Opistognathus aurifrons) in a 55 gallon tank with 6 inches of mixed substrate (aragonite sand, crushed coral, and Aruba shells) and about 30# of Fiji live rock. For external filtering we have a CPR backpack (OK) and an Eheim 2026 canister (worth every penny). Additionally there are some sponges, several Aiptasia, and various worms that came with the rock and for cleanup we have some janitors from GARF. (We also have a 75 gal reef tank with a bunch of corals from GARF and a few fish.) Today we noticed one of the jaw fish was holding its mouth slightly open and looking in we can see glistening beads. WOW! looks like we're pregnant! <Wow! you have a mouth full of eggs too?! How exciting and bizarre!...actually, Congratulations!. How wonderful.!> We are overflowing with questions about how to give the potential new arrivals the best chance to survive. Any sage advice? I can't find much of anything searching the web. We have your jaw fish bibliography, and will try to find Young's book on breeding. <yes, realistically...be prepared that this first batch is not likely to survive in the community tank with pumps, filters and predators... but do seriously consider a dedicated species-specific tank for breeding. Secondly, get set up with a live food culturing station promptly. Refer to Moe's marine handbook "Beginner to Breeder" or the Marine Aquarium Reference" for basic food culture advice. And do look up Florida Aqua Farms for algae, rotifer and shrimp culturing supplies and handbooks (they even have a plankton culturing manual)> Following are a few observations that I have not seen on the web: When the brooder needs to eat or do burrow maintenance he puts the eggs somewhere down in the burrow, does the work, then picks up the eggs when done. Since this whole operation can happen quite fast (a few seconds) the egg mass must be sort of sticky. From time to time in the past (while in quarantine and when first introduced) we would see the two sharing a burrow but lately they seem to stay separate. The burrows are about 8 inches apart along the edge of a pile of rock. At this point there is no evidence that these tunnels are connected. In quarantine, the substrate was not very deep so they had connected tunnels with several openings under a large piece of live rock. When first introduced to the 55 gallon tank we expected they would take a while to acclimate but they seemed to be right at home, maybe because we also brought in the large chunk of live rock. It did take a few weeks of excavating and trying different locations before they settled in to their current locations. They sure can move a lot of material around. <yes...and very entertaining! have you noticed them stealing shells from each other at night to cover their burrows...a hoot!> When the lights go out (sometimes a short time before lights out) both jaw fish completely cover their burrows. This cover is so complete there is no evidence that there was ever a hole there. After the lights come on they remove the covers. <ahah! I should have read further...hehehe> Have been looking for a way to tell the male from the female and don't see anything except the brooding. <difficult...but notice the enlarged folds of the buccal cavity (chin) and broader skull> Lee & Mary Powell <please write a follow-up... looking forward to future spawns! Anthony Calfo>
Breeding Pearly Jawfish Hi Bob, <cheers, friend from afar. Anthony Calfo in your service whilst Bob travels> I have a 200l tank with a pair of Pearly Jawfish in it. I have set this tank up solely for the purpose of breeding the Jawfish. <it is very exciting to hear an aquarist with a proper system for fish breeding> I live in South Africa so we do not get the Jawfish here very often as flights are long and the losses are great. <understood... a fascinating fish indeed> I have had the pair now for close on to a year and they have now started breeding. The female will really swell with eggs (Clearly visible behind the stomach). The female enters the males borough about 1Hr after lights on and spends about 15 to 20min with the male. When appearing again the male will be carrying eggs in his mouth. The eggs are white in color and are about 1mm in diameter. The problem is that the male eats the eggs after 1 to 3 days. <this is not at all uncommon with many young pairs... even the best suited mates often fail with the first several to a dozen spawns> I feed them once a day with a well varied diet which includes live food. I keep feeding them while he is carrying the eggs which he leaves in his borough to come and eat. Could the eggs be infertile? <quite possibly as they are a bit clumsy with each other at first> Should I try to recover the eggs from his hole when he is eating and then try and agitate them with a small pump? I would wait to see after several more attempts before trying to rear artificially> Could this work as I have read that some people hatch their Dottyback eggs in this manner? <yes my friend, but it is a lot of work and very tedious. Lets see if the natural parents don't evolve> Any help would be appreciated. Tokkie. <keep up the good work! With kind regards, Anthony>
Sexing Jawfishes 2/6/04 Hi (love you're site!) I was wondering if you new how to tell how to tell the difference of the Yellowheaded Jawfish. <the one that won't stop to ask for directions is the male...> I couldn't find it on your fish articles all it says is that it's hard to tell the with the Yellowheaded Jawfish. <true. Its not reliable, and best done with a group to compare to. Males have larger skulls, thicker lips and larger buccal cavities (chin-pouch so-to-speak). Rather like sexing FW cichlids. Anthony>
Breeding Jawfish Dear Mr. Fenner, <John> Recently, I noticed one of my Jawfish carrying eggs in its mouth. I have read the FAQ's page discussing Jawfish breeding but still have many questions. My questions are geared toward the raising of the Yellowheaded Jawfish (Opistognathus aurifrons) from eggs to larva to adults. Currently the pair is being housed in a 90 gallon display tank, with wet/dry filtration, powerheads, and a skimmer. I Don't think the larva will survive the display tank but I've been thinking of setting up a twenty gallon species tank, for the purpose of breeding. I would appreciate any thoughts and recommendations on equipment for this set-up. <A twenty might do... you should (quickly) read through Frank Hoff's works on food culture, start your gear going for same... see Florida Aquafarm's site re> Also, I have no idea what the requirements for caring for and feeding the larva and on to the fry (hoping they make it that far) should be. I would appreciate any advice you can give me, and any references to web sites or books where this may be discussed. Also, I was wondering if many people have had success raising Jawfish to adulthood. Thank you for your time, John <There are a few protocols. Take a look on the "Breeder's Registry"... Bob Fenner>
Info. on Opistognathid culture? Hi, <Hello there> First
off, I want to say that this website is great! I've just stumbled
across it while doing a search for info. (which brings me to my
question in a second...) and it is very cool that you (Bob) and the
other generous persons on this site are providing all this information.
:-) <Welcome> Ok -- on to my question: Do you know where I could
get information on rearing techniques for Opistognathus sp.? I saw on
your site that "some species of Opistognathids have been bred and
reared in captivity" and I was wondering who or what organization
I could contact to possibly get details. <Mmm, Frank Hoff's
works, general searches on the Net, there are some recent books... Do
you read German?> I recently completed my Master's thesis
project at a university on the East coast involving finfish culture and
I'm now on the West coast and getting ready to start up some
culturing of my own to possibly sell to LFS/warehouses in the area.
<Ahh! There is much anecdotal (as opposed to more scientific)
information/observational work on Jawfish reproduction... but many
species have been cultured.... though the principal (aurifrons) is
still mostly wild-collected...> Thanks in advance for any
information or advice you can give me. Sincerely, Kristin <Will help
you... more... if you'd like, on return to the States (where ref.
works are). Bob Fenner, in Quito>