Mandarin dragonet spawning log

[DaJMasta]

Haha, I'm not even feeding her space every day, there's just a ton of them, I feed it phyto just to keep them nutritious...

Between the actual cultures and the larva rearing containers that develop into pod colonies after a week or two of culturing, I have a LOT sometimes.

[DaJMasta]

She's 13 weeks/3 months old today, a little bigger (hard to quantify, but he definitely looks bigger somehow), very slightly more colorful, entertaining to watch.... but still not to full coloration.

I've read 3 months is about the number, and I've thought it was imminent for weeks now.... we'll see in a week and a half if she's got full color at 100 days.

 

 

[Origami]

You've done a great job here. Thank you for documenting and sharing it. I can definitely see signs of coloration in this most recent photo. It's exciting to see the changes!

[DaJMasta]

Another mostly normal week, a little new behavior.  Her color looks a little darker in person (at a distance) and a little lighter at night while asleep.  She's also picked up the behavior the adults have of sort of acting angry/territorial with their reflection in the glass - I wonder if the ~12 week mark is where they'd normally need to be split up if raised in a group of several.  In that first month where she had a sibling, they totally ignored each other, but it looks as if she would no longer do so.

Not quite to full color yet, and a similar look of bigger-but-hard-to-tell-how-much, so we'll see in another week, when she'll be more than 100 days old!

[YHSublime]

You can definitely see the color starting to pop through in your photo progression. This layman (if I was documenting this for others and remarking on color) would consider that color popping at 100 days, but not full color, obviously. 

 

And I know I continue to say this, but amazing job, I grumble about having to clean the glass and you're over here just breeding mandarins. 

[DaJMasta]

My main tank also gets noticeable algae on the glass every 3 days maximum and it often takes another day to actually clean it off the glass but thank you!

[DaJMasta]

A little update outside of the little one:

I got a male mandarin a month or so ago, spent a few weeks training it onto frozen food (I think this one took longer since I also added some pods early on), and introduced him to the tank as I would other fish.  In the first few hours, the original female chased him all over, and I ended up pulling him out near exhausted against the overflow and put him in one the larval rearing tanks.  He didn't seem hurt, just tired, so I gave him a week to eat and recover.

Yesterday, I moved him back to the main tank, but left him in an acrylic trap to keep them separated.  The female, who usually runs from me and hides in the back, was out and active and clearly aggressive for a bit, then active and interested for a few more hours, and gradually started acting normal, just noticing him when passing by.  He also seemed to get a little more confident and not immediately just fleeing when she acted aggressive.

 

Today, they were acting reasonable to each other, so I opened the door to the trap and he eventually swam out.  They had a few moments that saw both hovering and with fins up, but it seemed no obvious aggression or chasing, and they stuck around each other a decent amount.

After lights out, they spawned, and I collected maybe three dozen eggs, though I don't have a rearing tank that's empty, so they went in with some peppermint shrimp (another recent project in progress).  It may be a few weeks before I can do a proper batch again for a second attempt, but I'm very happy to have a spawning pair again.

[Kathryn Lawson]

This is so cool!! Do you mind sharing some info on how you trained your initial pair and now your new male to eat frozen food? Maybe a lot of the info I'm finding online is outdated, but it sounds like most folks have had issues getting them to eat anything but live foods, especially if wild caught. Also, your baby nearing the 100 day milestone is fantastic!!!

[DaJMasta]

I've been meaning to properly write it up/describe it, but it's basically like this:

The goal is to get them eating prepared foods as soon as they are fed, because they are not particularly fast eaters and will be out-competed to find the chunks by other fish unless they know to eat it as soon as it's offered.  And while they seem to universally like it, they are visual hunters (and ones with a high miss rate), and they simply don't recognize most prepared foods as being foods.

So my method is to put them in a mesh sided breeder box in the tank until they start accepting the prepared foods.  By keeping them in a confined space, their random picking around at things will be much, much more likely to accidentally eat a morsel of prepared food, and after a few of those, they'll start being able to recognize what it looks like.  Keeping them in a space where you can directly interact with them also makes them less likely to just run off when feeding time comes because you showed up at the tank, and the fine mesh sides keep the food in there.

 

So they go in the mesh box, they get fed twice a day with frozen of different types, and each morning I vacuum out the old food with a baster.  Typically, you will see some food disappearing in the first few days, but they won't actually be going after it as soon as it's offered for a couple of weeks - usually 2-3 weeks is what it takes them for me.  It seems that whole-organism types of food get accepted sooner (probably because it looks like a natural food), and I don't see any preference to the very small ones (like PE calanus).  I think it's better to get them onto larger foods anyways (and they can eat bigger pieces than it looks), because that means if they can slurp up just a few, they get a good amount of nutrition out of it.  I've had best (fastest) acceptance with frozen bloodworms, followed by mysis and krill chunks (though these are large).  PE sized ones are alright for grown mandarins, but I would stick to hikari or smaller sizes for smaller mandarins or with other small dragonets.  The first thing one of mine ate in training was the head of a krill from a mixed, chopped blend, and while it got it in, it spent a few minutes "sneezing" and whipping around its tail to try to get it all the way down.  I've also seen ruby red dragonets swallow bloodworms 2/3 of their own length, though it did take repeated attempts (which looks hilarious as the worm goes in and out of their mouth).

Especially if the mandarin looks thin, I'd recommend feeding pods directly for the first couple of days, but it may be that feeding pods alongside the frozen foods actually slows the uptake of frozen foods.  Don't consider them done with training until they will accept more than one kind of food shortly after feeding, and it's worth leaving them in the box a little longer if they're eating readily but still look thin - it will take a lot more effort to swim in the open waters of the tank, and they will be stressed somewhat from the new introductions, plus it tends to be that they take a few days to start recognizing when they're being fed prepared foods again, even if you use the same tools.  Also worth mentioning that my flow is entirely off for feedings, and I keep it off for 5-10 minutes.  They are not fast enough swimmers to catch chunks of food that are drifting by (I've seen them chase and not keep up with falling frozen foods...), so some time for the food to be settled probably helps a lot with how much they can eat.

I think so far I've trained 4 mandarins and 3 ruby red dragonets this way successfully, though there has been small tweaks and experimentation each time.

[Kathryn Lawson]

That's super helpful, thank you!!

 

How often do you feed them? I've seen a lot of people saying they need to be fed multiple times daily or have tons of pods always available because their digestive tract is small, but obviously whatever you're doing is working super well, since they're spawning!

Edited November 22, 2022 by Kathryn Lawson
additional question

[therootcause]

On 11/19/2022 at 10:59 PM, DaJMasta said:

"Today, they were acting reasonable to each other..."

"After lights out, they spawned, and I collected maybe three dozen eggs..." 

 

These two sentences in the same post made me laugh.  It's not what I was expecting at all - but WOW...great news.

 

Would you mind sharing some photos of your overall setup, photos/sizes of the homemade baskets, various tanks, and mesh boxes?  I really enjoy watching the close-up videos but would like to see the overall footprint of the setup along with the equipment that you are using to keep it all going if you don't mind sharing.  If you already have it posted elsewhere can you share the link? 

[DaJMasta]

I've been feeding the tank twice a day with frozen, though for the first few months of having two mandarins, I was feeding once a day.  I've got two mandarins and a ruby red dragonet in an e170 (~45g AIO), so I don't think pods are a huge part of their diet, even though I add some as residual from the farm a few times a week.  I think that they have a shorter digestive tract is a fact, but I don't think that means they must constantly eat - they do sleep at night, after all, and it's common to see the males (and sometimes a female) sort of protecting their territory in the evening (going after their reflection in the glass) without eating while doing it.

I think the necessity to continuously eat is more just the size of the prey - if they're only getting copepods, it could easily take several hundred or a few thousand to equal the same amount of nutrition as a single small mysis shrimp, so unless they get larger worms or amphipods, it's likely they have to spend most of their waking hours grazing just to get enough food.

As for the setup, it's probably more basic than you envision, but I can run it down at least:
They were raised until settlement in a 10 gallon brute trashcan, about 80-85% full with saltwater.  I used three small always on heaters (7.5W each, IIRC) for heat and a not-reef-brightness LED light in the center over it.  I also had an airstone dropped on an airline in the center of the tank, set fairly low for a slow circulation in the tub.

After settling, I transferred the then two juveniles to a 10 gallon tank plumbed into a 30 gallon system and put them in a 3d printed tray I designed for some earlier spawn work.  It's basically a cylinder with fine mesh on the bottom (printed parts sandwich the mesh and it's glued into place), with the side sliced off and little plastic paddles made so you can use aquarium magnets to hold it on to the side of the tank and have a peak inside.  Because the seal along the glass needed to be tight, I left a semicircular cutout along the edge and put in a length of silicone airline tubing to use as a rubber gasket.

 

The smaller one is a complete tray, the bigger one is a stretched version that's newly printed and not yet assembled.

 

This is what the 10g with the little girl looks like today (that's her in the bottom right) with an extra light over it and the lens of the camera on the left.  The tank needs an algae magnet clean which it shall be getting shortly.

And one of the pictures captured from that setup of her 15 weeks post hatch:

A little greener by eye, a little more time spend on the side walls and on the little piece of lock line instead of just puttering around the bottom, but basically the same look/activity as last week and little farther along with coloration and size.



Oh and the mesh box used for teaching the adults to eat prepared food is just the standard Petco one for $10, nothing particularly fancy, I like to use an algae magnet inside it to keep it up on the glass way more reliably than the single suction cup.

[therootcause]

Thank you for sharing!   I admire your ingenuity in creating the half cylinder baskets for rearing the fry.  I don't have a 3d printer but with a Dremel and a five gallon pail I may be able to create something similar with mesh sides and base.  I think you are really on to something and good luck!

[DaJMasta]

 

[DaJMasta]

 

17 weeks and a bit - 121 days, she's not growing all that quickly but is a little darker.  Moved her into a larger holder and fed some prepared food before adding a real pod population, hopefully she'll get some and keep growing and coloring up.  That's a Salifert test kit vial, so she's about half its width, so 10-11mm.

[YHSublime]

Slow and steady!

 

[howaboutme]

Wow! I don't think I fully grasped how small it is until now. Nice picture.

[DaJMasta]

Well, the news this week isn't good, unfortunately.  I lost her on Sunday.

 

 

124 days old, not yet to full coloration.  I don't know exactly what went wrong, but I have some suspects:

The day I took that picture I moved her into a larger space (about 2x the volume, same footprint) with a coarser mesh, and fed as usual.  I think the combination of the new space (fewer residual copepods) and the coarser mesh (more able to escape), probably lessened the available food.  But perhaps more critically, I found out a couple days later that my Tisbe culture had crashed, so while I was feeding plenty of tigriopus and apocyclops, it may be that neither was easy for her to actually eat, or perhaps they were more likely to escape, and I think the combination of things ultimately lead to her running out of usable food.

I did realize Sunday morning that she was acting more lethargic, and fed half a day's total harvest directly (several times a normal day's addition to the vessel) then, but she only ended up moving an inch or so from that point, so it was probably too late to get the nutrition she needed.  The crash of the tisbe culture may actually explain the slower development and reduced growth in the last few weeks if that was her primary food source - I don't know how long it has been since it stopped producing.

 

I also tried some prepared foods (TDO B1 and B2) added to the new vessel when I started it.  While the coarser mesh should have meant plenty of water exchange with the tank it was in, there is some slim chance that this newly added food fowled the water somewhat.  Not likely given the quantity and exchange with the surrounding tank, but a possibility.

Despite 4 months of progress coming to an end, while somewhat discouraged I'm not deterred.  I have a spawning pair and fairly reliable source of eggs, and I've actually been trying some runs to get new larvae.  Nothing settled yet, but I think I'm getting some useful information on the conditions they need (seems like very low flow is actually bad for them, and while higher flow I don't see the larvae easily, they are visible in the hours after when I turn it down).  I will try some additional runs to try to hone in on what is best to make them work - I hope to get more than just two settled out of a batch.

I've also got copepods on order to arrive tomorrow, and this time four new species.  My intent is to restart the tisbe culture and then swap one apocyclops culture to something new, but I've got three new candidates (acartia, pseudodiaptomus, euterpina) and only one of which I've attempted before.  Two of the new ones are also some version of benthic, which should be good for the mandarins.  I'll see what I can grow in and keep going, and hopefully diversify my copepod offerings considerably as apocyclops as 3/5 cultures doesn't seem to be great for a lot of my larval rearing projects.

 

I may also print another of the larger vessels and use the finer mesh in the base, but if growth rates are better, the coarser mesh may be just fine as an option, but at the very least having a second one so I can swap one out to clean it is useful.


The journey continues.  It's sort of rough making all these attempts and losing 100% so far, but no one's claimed it was easy and honestly, I think peak survival rates in the wild for most marine larvae are probably only a couple of percent, tops, and if left in the display nothing would survive, so I certainly don't feel like I'm just slaughtering them with my attempts, despite the survival rate.  Hope to find a more reliable way to get them to settle soon and have many more attempts at these later stages.

[YHSublime]

Glad to hear you're going to keep at it, only way to learn! 

[AlanM]

I agree that getting this far is pretty amazing.  

[howaboutme]

I applaud your efforts! Great job. The journey continues. 

[Kathryn Lawson]

Sorry to hear about your loss, but I'm glad that you're going to continuing trying!

Somewhat relatedly, I work for a major university and have access to most academic papers. I went down a rabbit hole the other day finding a bunch of journal articles on raising marine species including mandarins! I also pulled some on copepod and phytoplankton cultures and methods. If you (or anyone else) is interested, I can send you the PDFs!

[DaJMasta]

Thanks, I've found a few for each online (as well as an article on raising mandarins), but it's not always with the same goal in mind, and a lot of them seem to be based on older techniques (feeding artemia nauplii, for example) which doesn't directly correlate to what I've been trying as much.  If you've got something of particular interest, though, I'm all ears.

An update:
I had a couple of captured eggs that I tried making runs of and was seeing lower fecundity and then losses in the first week - there were a couple of potential reasons, one the failing tisbe culture (which did actually have individuals that I collected and grew out to add to the new culture).  I also noticed a similar reduced spawning and fecundity earlier, so it could be a sort of periodic lull.  I've also got some shrimp going in my vessels right now, so newly hatched larvae would have a tough run.

In any case, my next run I should be even better prepared for.  I started several new zooplankton strains and have Euterpina growing readily with Acartia growing in, as well as Tisbe, Tirgriopus, and Apocyclops still in production (and producing well again).  I've also got an extra species of phytoplankton which has the potential to increase nutrition of the copepods or output - but I have no evidence either way for that.

In addition to the increased food, I'm going to try two specific things that were described in a MACNA 2022 talk (

)

The first, is that I will start the eggs with almost no flow in the vessel, just a trickle (a bubble or two a second) in the middle to try and keep temperature and oxygenation layers from separating.  The second, is I will actually do a water change or two.  Basically, this talk outlines their methods for culturing several kinds of fish, and they mention specifically that they hatch eggs with no flow, then increase it over time, and that it's been shown that high nitrate levels (even moderate ones) can effect larval development and even growth defect rate, even for organisms that otherwise seem to tolerate pretty much any nitrate level you can keep your tank at.

In my more recent tests I've been experimenting with flow rate and have definitely seen that lower flow rates are better for these guys, so I plan on starting with the trickle, then moving up at one week and then at the end of week two.  I'm also planning ~5 gallon water changes at similar intervals, maybe on the same day, to keep the nitrate levels down.  I think feeding exclusively live food has had a positive effect on water quality, but buildup of nitrates could explain a number of my later-stage losses, and I may even have worked out a system that makes it reasonable to do without removing any larvae (always tricky, especially when they can't swim well).


Though the next run of mandarins is probably at least a week off from starting - I've got some peppermint shrimp larvae going (and the last run went 4 weeks, close to settling) and just caught my first batch of pederson shrimp larvae last night.

[Origami]

You've done an amazing job. It's been incredible to follow this journey and, while it ended the way it did, I think that we all learned something. I applaud the effort and hope that, one day, we can follow along on another journey like this one.

[DaJMasta]

Made a couple of attempts since the last post, but basically just collecting eggs and adding them to already running larva vessels, trying out different aeration settings, and then trying a water change (which I think was dumped in fast enough to injure the young prolarvae in there).  Reset the larval tank last week and developed a new version of logs I'll keep for each spawn attempted - I had some marks on the vessel and some notes in a notebook, but not really a specific plan to stick to, a substantial record of an attempt, or a way to make more comprehensive notes.  So I drafted a document, started off a set of eggs, and had none hatch because the RO used for the new water was still 4 C under temperature late at night when I felt like I had to add them to the vessel and go to sleep.

The next day, I removed the eggs I saw, collected another (bigger) spawn, and started again:

 

So as of today, out of more than a hundred eggs, I should have more than a dozen prolarvae, shortly they'll be able to eat.  I'll try slightly smaller sieve size for initial feedings (copepods that fit through a 150 micro screen and are caught by a 45 micron screen), and see how they do.  I will hold off until the weekend for the first water change and try to be gentle pouring the new water back in to try and keep from injuring the larvae.  In recent attempts I've had a lot of trouble getting them survive a week, but I'm hoping the clean vessel and more rigorous plans should help.

I also got an underwater camera (Olympus TG-6) a bit ago and figured I would give it a dunk to see what they looked like while still in the tank.  The prolarvae at this age seem to like being near the surface, and while focus is really tricky (especially when you can't see the screen because of the angle), they apparently don't pay too much heed to their orientation at this age: