Mythraculous Sculptus (emerald crab) spawn

**THEJRC** · 10-13-2008, 01:38 AM

Well all, I've managed to get spawn off one of the emerald crabs in my observation system this evening. Pelagic fry was noticed around 9:30 PM and are still going strong as I type this!! They are kept in a skimmerless, filterless system fed constantly with microalgaes and now several copepod cultures so I am hoping for the best!!

From the rather spotty information I've found the pelagic stage lasts around 8-10 days so I'm hoping I can keep the planktonic food cloud thick enough during that period. If anything they've chosen the proper system to spawn for sure!

I will try to keep everyone posted but for now it's time for more research!!!

**CarmieJo** · 10-13-2008, 02:11 AM

Joe, that is fantastic! I will be keeping up with this!

**THEJRC** · 10-13-2008, 03:24 AM

I'll be posting most of my efforts on dibs as per usual but it's just so exciting, here I am several hours after the fact watching the little guys bop around happily munching on the microalgae mixture I toss in. Most frustrating part is the total lack of publicly available information on these guys. I've run across a few papers here and there in all the wonderful journals I cant afford and have gleamed some okay information from the abstracts but nothing particularily useful given my timeframe and situation.

Thus far I've established that the larvae is photoactive (attracted to light) however not so much so as to rush into brighter areas. With overheads off they tend to slowly migrate to the lower sections of the tank (as a faint glow from the lower tank shines through since the specimen tank is bare bottom) and when lights are flipped back on they slowly move to the top of the water column.

Movement is uncoordinated and jerky, they resemble harpacticoid copepods in the water column with quick short bursts of movement though I have not seen any signs of settling or surface clinging yet. The eyespots are so large that they are visible with the naked eye as a black dot on a white dot. They appear to expend quite a bit of energy when food hits the water, rushing to eat but when sated settle in and slowly float with the occasional flip or flop to avoid faster currents.

I did manage to slide mount one but I havent been able to get a good camera shot through my scope, perhaps for POTM eh.

**Amphibious** · 10-13-2008, 06:40 AM

Congrats!

Since nothing worthwhile has been published on the spawning of Mythraculous Sculptus (emerald crab), your published thesis will be expected soon and greatly appreciated.

Dick

**saltaddict** · 10-13-2008, 06:53 AM

Congrats!! Good luck and keep us posted..

**bbl_nk** · 10-13-2008, 02:45 PM

Aweosme! Love to hear when another species is tank popagated!

**THEJRC** · 10-13-2008, 09:04 PM

he he published theisis he says.....

so far so unsure, most of them appear to have settled over last night and today. While I have a few still in the water column some have been noticed on the glass bottom as well as on rock and macro in the tank. I'm seeing less than I saw last night but this is to be expected I suppose. Since the sump is neither clear sided nor easily inspected I couldnt tell you how many may have passed through the unscreened overflow down there but I can say that I've noticed several in the other sections of tank.

At this point i am feeding higher amounts of pelletized feed to curb the possibility of predation from mysids and the isaeidae amphipods I've been examining. I wish I were better prepared for this instance for sure. I can only hope for a small survival rate. I have been able to re-create the photoreaction test several times at this point and have shaded areas with overflows. Unfitting with my original theory however they seem to be more interested in easy capture of prey rather than picking higher / lower flow areas. At first I thought they were avoiding areas of higher flow however at this point they appear to choose whichever areas of the tank are more saturated with food sources rather than areas with flow considerations.

While none of this is particularily useful as of yet I did re-examine the tanks parameters over the last few days to figure out what may have triggered the event. The original stock level was two crabs, while not positively identified they were "quick hack" identified as a male and female before addition to the tank. The tanks salinity was elevated (1.030) and there were some changes made starting friday (10/10/08) afternoon. I began to perform slow water changes to lower the salinity, since this system typically only sees water changes in the form of salt water siphoned out here and there to be replaced with fresh water (not mixed salt water) to help balance salinity the addition of new salt water most likely aided the process through the reintroduction of trace minerals. As well our temp has been dropping, salinity drop to near normal levels (still upper range where I like it at 1.026/7) along with temp bounces from 80-74 may have helped however the spawning event itself I think was spurred by salinity and through the addition of 4 new specimens (3 female 1 male) on saturday afternoon. While it's less than likely that the new specimens fertilized the female with gestation in such short time (28 hours or so) it is very likely that the addition helped push the envelope for survival instinct.

Once this run is through I will most likely isolate several specimens (or obtain new specimens for isolation) and attempt to recreate the instance via temperature / salinity adjustments.

**rayme07** · 10-13-2008, 10:51 PM

Thats pretty

. Dont you love when things breed in your tank it makes you feel like your tank is healthy and going strong which it is. thanks for sharing. keep us posted. Thanks

**"Umm, fish?"** · 10-14-2008, 12:46 AM

You go, Joe! I really love the experimental way you approach your tank.

I do wish you lived less than three hours away, though.

**rroselavy** · 10-14-2008, 01:59 AM

I'd love to see pics of any of this if the opportunity presents itself...

**CarmieJo** · 10-14-2008, 03:25 AM

Scott, there aren't any pix on DIBS either but you may want to check out his more detailed thread here Project DIBS Forums.

**THEJRC** · 10-15-2008, 01:03 AM

he he sadly I've been more detailed on this one here at talking reef than on dibs, it's a time crunch for me lately as I'm in the middle of merging my company with another... and of course all the other daily crap I call work...

Heres the two decent pics I managed from the scope, pay close attention to my hasty and very terrible slide mounting job... god I suck Pics are at 40% magnification, yes these guys are tiny for sure!! I've got copepods larger!

and of course without filter

as a general update I'm noticing all of three still swimming around in the water column, they have gotten noticeably larger and I will attempt to snap a picture through the tank glass (though my first run just looked like white dots). I can only assume two things.... either
A) most have settled or,
B) most have died

I'm hoping for A of course, only time will tell.... given the documented 8-10 day average to exit this planktonic stage I've got a long wait!!! I'm curently biding my time planning a test tank to attempt to find ways to induce spawning. My theory is that if I can induce spawning more often I can then use the outputs of that to fuel another string of tests to improve survival rate of fry.

**saltaddict** · 10-15-2008, 07:52 AM

Lucky you! Very nice.

**CarmieJo** · 10-15-2008, 10:48 PM

Joe! Thanks.

**rayme07** · 10-15-2008, 11:17 PM

Great pics

Thanks for the update.

Originally Posted by THEJRC

I've got copepods larger!

LOL Thats funny

**THEJRC** · 10-16-2008, 01:18 AM

he he, so I just spent the last 15 minutes on my feeding / beer cycle (I feed the tanks plankton and feed my gut beer).

No more signs of any in the water column, I'm beginning to get depressed. I know I cant say I've lost them because I havent waited long enough to tell but I also cant say I still have them because well.... I havent seen them. So now it's wait and hope.

In the between time I've been examining all the wonderful things I need to do so that this doesnt go the way it has this time. I would have loved to provide a much better much more accurate thesis on how this works and my findings but point blank... I was far far far... far... from being prepared. So heres the changes...

1) I will be setting up larval examinatinon tanks in an area somewhere (no clue where yet... maybe I'll sell the fridge and use that empty space) so that I can move samples of larva to a separate isolated and controlled environment for examination and experimentation

2) I will be setting up a dedicated system to examine what causes these guys to spawn (this is the longer term obviously, requiring a full system and of course more livestock... yay)

3) I need to buy new notebooks... (yeah It wasnt until I went to journal something that I realized my notebook has been full for months.... stupid me)

4) The tripod needs to be prepped and not buried beneath crap in the attic

5) I have simply got to loosen up and mount slides better

thats it for now, I'm sure I will find about 300 more mistakes I've made between now and the 10 day mark when I can say whether or not anythings made it. Wish me luck!

**CarmieJo** · 10-16-2008, 11:42 PM

I hate waiting. My tripod lives in my fish room!

**rayme07** · 10-16-2008, 11:48 PM

Sounds great hope you get them to spawn a second time and your ready I would love to follow the process. Hope you have better luck from here on out. Thanks

**THEJRC** · 12-22-2008, 03:49 PM

well I suppose it's time for a general update, several spawns and adjustments later I can now sucessfully induce spawning pretty consistently. I've got a few more runs to do before I consider it a set in stone success but I've been able to remove a lot of the unknowns. I'll be journaling more on my blog at www.copepodgeek.com Home

As a general overview this weekend was the big turning point, I now have a kreisel set up for the zoea grow out and was able to collect two full spawns (one saturday and the second this morning) for placement. While this is the first kreisel and grow out attempt and I'm already finding errors its a good thing. If I can have continued success in inducing these guys to spawn I'll have a lot more chances at figuring out the grow out protocols as well.

Wish me luck

**rroselavy** · 12-22-2008, 04:30 PM

Originally Posted by THEJRC

As a general overview this weekend was the big turning point, I now have a kreisel set up for the zoea grow out and was able to collect two full spawns (one saturday and the second this morning) for placement.

Wish me luck

Dude. I'm not worthy!

I don't even know what a kreisel is. I will definitely check out your blog...

**THEJRC** · 12-23-2008, 12:29 AM

Originally Posted by rroselavy

Dude. I'm not worthy!

I don't even know what a kreisel is. I will definitely check out your blog...

he he if you saw a real kreisel and then compared mine you'd reverse the not worthy post for sure... Mines a hack job at best (and worst yet, it aint workin!)

Basically a Kreisel is a german design denoting "Carousel" which was originally intended to keep planktonic creatures in suspension by creating a circular flow within a tank. Jellyfish tanks are typically Kreisel tanks. The tank is like a sideways cylinder and water enters via a spray bar at the top of one side pushing against the curved side of the tank, this pushes water down and around in a slow circular movement. Water exits on the opposite side through a screened outlet.

The biggest technicality with the design is maintaining proper flow, water flow must be enough to keep the entire body of water moving in a circular pattern but not so much as to centrifically push your inhabitants outward against the sides of the tank. The second problem is in the outflow screen (this is my largest wall currently). The screen must be of small enough mesh to contain the planktonic critters but shouldnt clog every five minutes either. with my design I'm still working on the details of the inflow and the outflow. The general design of the tank was fairly simple. I merely cut a peice of acrylic to slide inside an old hang on back refugium and propped it in so that it was rounded. I've got to work on the sealing of the thing but for a quick half hour job it'll do for now. The spraybar has been recently re-invented (ala 2 hours ago) and as soon as the pvc cement cures for a day I'll pop the new one in hopefully gaining better control of flow.

Unfortunately I'm already noticing loss of zoea however there are a few visible specimens left within the kreisel. I dont really expect to have any survival rate on this go round simply due to lack of preparedeness with the kreisel and of course the whole idea of working the design in. Luckily I can induce another spawn in 3-4 weeks which should give me ample time to correct the flaws from this go round. Thats the trick, trial and error and lots of observation!!! The more spawns I can obtain the more opportunity I have to correct the issues with each grow out stage. This will be grow out attempt number 7 for me from all tanks and spawns previously and thus far I've had no luck (havent been this focused on grow out to speak of yet either though).

The most frustrating part though, is the lack of information out there from others!! I'd LOVE to hear from ANYONE who has sucessfully raised these guys to megalops and beyond. Someones got to have some info out there for my brain!! Bueller???

**CarmieJo** · 12-23-2008, 11:14 PM

Joe, I don't have any insights but I am really enjoying following your progress!

**THEJRC** · 12-29-2008, 02:12 AM

extremely exciting day today as yet another spawn occurred this morning. The kreisel has been torn down and is currently being re-worked so naturally it was not ready (doh). I did however get the chance to build what I now coin the "Aime Device" (after the poster aime on mofib who pointed it out) Marine Ornamental Fish & Invert Breeders Association :: View topic - Larvae collection using a trap

I had great luck with my version of the modified aime device and will continue modification to suit. Currently I am leaving the zoeae in the vessel of the device for an attempt at grow out and am feeding with a culture of live rotifers and copepods cultured in Nannochloropsis, Tetraselmis, and Thallasiosira at the rate of 50ml per hour via an enteral feeding pump.

So far we're on around the 8th hour and all seems well except for a few small problems (the zoea seem to linger at the exit screen, whether this is for food capture or other reasons is currently unknown) I will continue to work this process until either A. zoea reach megalops or B. Zoea perish. If they all perish, I'm off to re-start my induction cycle (which is what I set out to do today when I noticed the spawn in the first place).

I have started a slightly more technical thread at project dibs
Project DIBS Forums

and as always will be updating my copepodgeek site when I get the chance
www.copepodgeek.com Home

For those of you interested in the Mythrax crab by all means give it a shot, I am wholly interested in someone elses experience / views on rearing this species. If your currently working on something else such as clown breeding and the like I highly recommend looking at the mofib post listed above as the larval collector (and subsequent variants) are very useful and the thread itself is one of those that should prove handy for many many people. As always DIBS is my favorite board for reading with a great well focused community and an excellent vision. Through DIBS I've been able to focus my curiosity and make this hobby much more long lasting and enjoyable for myself.