Mandarin dragonet spawning log

[YHSublime]

You probably covered this, but are you growing phytoplankton, or culturing specific pods for feeding? 

[DaJMasta]

Yes, I think live food is likely a requirement for most larval stage creatures and while artemia nauplii are a popular option, it seems like their nutritional profile is somewhat worse and the maintenance seems a bit more than the cultures (maybe the same?), and I like the idea of maintaining a population and sort of farming them rather than just buying tons of brine shrimp eggs, hatching them, and feeding them to things.

 

I've got 3 kinds of phyto currently in production: tetraselmis, isochrysis, and chaetoceros, and I've worked with nannochloropsis in the past and have a culture of thalassiosira that's mature enough to start feeding to the copepods I've got to see if they will eat it.  I'm making roughly a gallon a day, two rotations of four, 1 gallon cultures harvested after 6 days.  Then I've got four mature two gallon cultures of copepods, 3 of apocyclops and 1 tigriopus, of which about 24oz from each is harvested and fed each day.  I've had a long term culture of tisbe pods going, but the production was always sort of low and since they ate regular food (detrius) and not phyto, it sort of complicated the maintenance routine.  I've tried both parvocalanus and pseudodiaptomus in the past, but had issues maintaining a continuous culture.  While I lost a lot of them either on or shortly after arrival, I've got a "culture" of each started (maybe a dozen or less individuals, really hoping to see some more in the next week in the parvo culture in particular as it looks the thinnest), so while it will take a while to grow out, I hope to be able to offer those as feeds - and it seems like parvocalanus is the one a lot of people see as the 'magic' copepod, as it's very productive, slightly smaller in nauplii stages, and still fairly easy for larva to catch it as prey.

[AlanM]

If you'd like to try artemia nauplii on easy mode I have one of those Hobby brand black plastic hatchers and some dry eggs.  It's super duper easy to hatch them and harvest them separate from the eggs within about 24 hours, and I'm fairly local to you.

 

https://smile.amazon.com/Brine-Shrimp-Direct-Hatchery-Dish/dp/B079C6BN2B

 

 

[DaJMasta]

It's not so much the equipment as it is the constant supply of eggs, but I know it's manageable... I honestly don't know why I'm so resistant to it, though I think for more difficult organisms, the nutritional profile is a problem using only artemia nauplii.  I seem to remember in a MACNA talk about home breeding of more difficult species that there were a number of larvae that just haven't been successful using artemia that were finally raised up on copepods - though it was parvocalanus that was getting the credit there.

 

With the run currently going, I got four consecutive days of spawn, this evening without a fifth, and I've added them all to the same vessel, so I've got larvae and prolarvae at 24 hour intervals all together and it's tough to tell what is working and what isn't, but they're getting twice daily feedings of apocyclops and tigriopus fed with diatoms as well now and all through a 200um screen.  In a few days time, I should get an idea of what's still surviving, but from as soon as they were able to feed, these larvae had copepod nauplii in front of them.

 

I finally got a decent video of the spawning with last night's spawn, though, as after a few at the top of the tank, they started spawning low or in the back, and it's been tricky getting reasonable lighting conditions since they basically wait until its only moonlighting.  But here there's an attempt, a showing of some of the nocturnal fish in the tank, and then a spawn.... followed by a cardinal that was fed twice and which ate some porcelain crab larvae half an hour earlier which went to town on the newly released eggs.  Still managed to get a couple dozen from this spawn, though.

 

 

[ScooterTDI]

Yea, there are a number of problems with artemia. Mostly, they are too big for most species and don't swim "right" to entice feeding, but they are also deficient in DHA which has been found to be critical for early development of marine fish.

[DaJMasta]

The previous run, despite my efforts, came to a close with no substantial progress made.  I had larvae in there for more than a week straight, but because of the four consecutive days of new eggs, it's impossible to say if I actually got anything lasting as long or longer than that earlier batch with one to 6 days old.  The copepods were more "enriched" with diatoms, the cultures were grown in, the food given was all from the 200um screen, and the lights remained on most of the time - no real difference.

 

The parents took a few nights off, but have spawned again tonight.  With the slowness of the new copepods growing in (and I reordered cultures, I don't really think the parvo one I've got will make it) as well as the artemia talk earlier in the thread has given me an idea for a hybrid approach.

 

Tomorrow night late, I will start a batch of artemia from eggs with the bit I have in my freezer, and I'll see if I can start a quarter teaspoon or so each day until I run out, which I'll feed to the larvae around the 18-20 hour mark, starting at 48 hours after spawn.  Starting at 60 hours post spawn, I'll also begin feeding sieved copepod nauplii as before with the hopes that they can catch a few and benefit from their nutritional content and then eventually transition onto them when better able to catch them.

 

While not the procedure I hope to eventually use, it should give me a good shot at getting through this early development period, and I've read of other people doing runs of them with just artemia nauplii early on, so the lower nutritional value shouldn't be the limiting factor to success, even if it limits the overall success rate.

 

Otherwise, the new cultures to try and get going should arrive Saturday (though the pseudodiaptomus culture I have now seems to be growing, at least, though still only a dozen or two adults) and I've gotten 250um mesh to see if I can get a little bigger copepods harvested that haven't fully developed their ability to run fast - will have to run a batch through and take a look at the activity in what's been collected.

The run begins again!

Edited March 24, 2022 by DaJMasta

[DaJMasta]

My inexperience with artemia is shining through, but they seem to be doing alright.  I harvested and fed the first batch of artemia nauplii yesterday, and with 24 hours to hatch, I don't think a huge percentage had hatched yet, since the eggs were old.  That meant almost no egg shells removed and much less clear looking larvae baskets.  I also underestimated the output of a quarter teaspoon of cysts, and while there are plenty of mouths for it, I don't think the larvae need anything close to the quantity introduced in the first feeding.  I think later feedings will be done with a couple squirts of a pipette from the concentrated harvest rather than just pouring some in...

 

As a result, I need to thin the feed density in the larvae basket, so I took a half a baster of water out of it, put it in a petri dish, and got sorting.

 

I did two rounds of this so far per basket, but will probably do another couple later today.  The round balls are eggs (no idea if hatched or not), the yellow/orange smudges are the artemia nauplii, the yellow things with eyes are the mandarins at 2.5 days old, and the big thing is a standard disposable pipette - my calipers say 2.7mm outer dimension at the tip, so these larvae are probably about 2.3mm long or so.

 

 

Behavior wise, they seemed to be trying to hunt when the artemia were introduced yesterday!  Earlier behavior than with the copepods, but looking at these guys under the microscope today, perhaps not a high hit rate even with the easier targets in the first 12 hours.  Of the four in the image above, I think the red spot in the one is a single artemia nauplii, though the extra 12 hours of growth for the artemia I think means a new zoea for them and a larger size, so the new ones this morning should be a tad bit smaller.  This morning saw the first dosing of copepods (apocyclops, including tigriopus in the evening) with my newfangled 250um screen.

 

Slightly related: since I have artemia going and have reports of them working as a sole food source for several creatures I've been attempting, I collected some other larvae to try with.  I got a skunk cleaner shrimp spawn two nights ago who got chaetoceros diatoms and copepods on the first day but will get artemia with the mandarins every day, twice a day, and last night I got a sexy shrimp spawn too!  The sexy shrimp are a bit smaller, so I'm not sure if they're able to eat the artemia yet (12h post spawn), but I've heard artemia work, so I've offered it to them.

 

 

Some more eventually good news: I got some new parvocalanus and pseudodiaptomus from algagen after the last cultures didn't really seem to make it.  I checked salinity and they are both at 35ppt, higher salinity than I usually keep my cultures, and I've been even more careful with acclimating them and feeding them.  Only a day in now, but both are seeing movement still.

Edited March 26, 2022 by DaJMasta

[AlanM]

For artemia I highly recommend that Hobby brand breeder I linked earlier.  

 

Here's a picture of just nauplii, no eggs.  The eggs stay floating outside the central sieve, and it's very easy to pull up the sieve, see the pink goodness of nauplii on the bottom, and swish it into the water to introduce them.  I have unfrozen eggs (6mo old) and an unused hatcher if you'd like to try it out.

 

[DaJMasta]

I appreciate the offer, but I don't think I need it, I just need to refine the method a bit.  If I were going to keep up artemia production indefinitely, something with a hatch chamber and a harvest chamber would be really helpful (or something that gives a similar effect), but I've got no trouble growing them from eggs, they're just slower than I'd like (no elevated temp probably helps, but the current bag of eggs was opened in July and then frozen).  In any case, I'm around during the day so I've been able to just keep the eggs percolating and collecting occasionally with a flashlight and a pipette.  Also managed to clear most of the floating eggshells with a few rounds of picking through things manually, though the density of artemia in the little baskets is still quite high, even with hundreds dumped in each pass of the petri dish.

 

 

No great idea of how they're doing this evening, but I know there are still some in there.  Will probably sample into a small container tomorrow night to see if I can see them with food in their stomachs.

[DaJMasta]

Update, no great results but I think I understand artemia now

 

Basically, that initial batch of artemia added was way too much, way too soon, and I don't give it enough credit as a food.  I poured in a third of the culture (1/4 teaspoon, 24 hours after hatch), and that meant thousands, literally, of nauplii and all of their egg shells and unhatched eggs, plus the eventual added copepods.  I saw literal orangey-red clouds of artemia in the little baskets with larvae, and I think the quantity of food was overwhelming, then the quantity of waste fouled the water, and this goes for almost everything I added them to.  In the case of the skunk cleaners with this method, there was a lot of debris from the eggshells, but then I accidentally submerged the top of the kreisel when cleaning another, so I think a lot got out and the collection wasn't a massive amount.

 

I can now see why artemia nauplii are so popular for freshwater aquaculture, especially - the amount of food you get per volume and effort is staggeringly high.  A quarter teaspoon of eggs is easily 10,000 nauplii or more, and they hatch just in saltwater with aeration, and can be collected with a flashlight, a pipette, and just removing the air to let it settle.  My current method is to keep the eggs in a half gallon jug filled a little under half with aeration for 24 hours, then transfer them to an open topped cup, tilt the bottom, blow away the sunken eggs, and use a flashlight to gather the nauplii in a clear corner.  In a couple of mL of water, you can collect 500+ nauplii each collection, and while 24 hours on my current batch of eggs and room temperature is maybe a fifth or less of the total number of eggs hatched.  That means I can keep this cup aerated for the next 12-24 hours and continue to collect them the same way, with the biggest concentrations around 36 hours after they get started.  That also means I can do a bit less than a quarter of a teaspoon once a day, whereas I started the last run doing a full quarter teaspoon twice a day - it's just too much.  I also cleaned the pump that powers the flow in the kreisels - it was set low, but slowed with gunk, and I think the low flow under the baskets also means it's easier for water quality in the basket to degrade when overfed, but I think the free swimming larvae are also fine with it, so it's better to leave it higher than it was.

 

My mandarins haven't spawned in the last few days, so I'm waiting on them to start my next attempt (the new moon cycle in the lighting was last night, which could be related), but I had an interesting new spawn two nights ago.... my newer pair of fire cleaner shrimp.  The spawn was massive, the larvae look just like skunk cleaners but start with several red dots, but since I've figured out some basics of brine shrimp, I've been feeding them with my newer techniques.  The first day, I fed them without blowing the sunken eggs out of the way, and I saw a bunch of larvae grabbing onto the eggs I dropped in along with some with caught artemia!  I've kept the eggs out since then and still have a cloud of them, I will see how far they can get and will either make a new thread or just add to the skunk cleaner thread, since they're closely related.

Back to mandarins, the plan for the next spawn is as follows:

Collect eggs, drop in basket

Hatch at 12 hours, eyes and mouth at 48 hours

Feed artemia and 250um sieved copepods starting at 60 hours (2.5 days), and try to keep artemia density to 5-10 artemia per larva

Feed artemia during the day as is convenient (as they hatch out over time), trying to keep a low enough population that I can noticing them disappear between feedings

Feed sieved copepods morning and night every day in addition

 

I'd expect around week 2 that I can drop the artemia, but I haven't gotten that far and don't know how big/strong they will be by then.  This is probably also about the time I dump them out of the little basket into the main kreisel for more space and without fear of them swimming through the coarser 500um netting.

 

I'll also try to get a few mandarins out to look at each day, probably in a petri dish.  I used it a bunch when sorting out the eggs/nauplii from this last batch, and slightly zoomed out and with more space to move around, I feel like I'll be able to see behavior much better outside the kreisel rather than in the tiny beaker I was using before.

[DaJMasta]

An update to the last post and the future:
I got some eggs and followed that recipe, and ended up with somewhat worse results than before.  I had fewer eggs than I thought I had collected, but still a dozen or two prolarvae, waited the normal time, added artemia, then added copepods, and while I saw feeding behavior, they didn't really last any better than before - about 4-5 days.  The food concentration may not have been right, but it was much improved from the last attempt, and maybe the vessel isn't ideal - I saw longer swims before attempted strikes when hunting, so maybe the small size is a hindrance?

 

That said, I'm also not totally sure artemia are the right choice.  Yes, there's the nutritional issue, but they also seem too big, this is a comparison of a larva with some of the artemia nauplii added:

 

I know their mouths are big, but still the artemia look bigger than I would have expected.  I wonder if maybe there are too many larger ones (maybe I should sieve them as well?), or if my artemia are hatching out to a larger size than some.... it's hard to say.

The parents took a few days off of spawning and did again last night, and again I've got prolarvae, but the plan for this time is different: I'm going to feed them parvocalanus.  I've got an about 1 gallon culture going pretty well now, and while I want to transfer it into a 2G vessel and grow it into full size, since i still have two days until I need to feed anything, I plan on starting to feed the culture to them (and only them until it's grown in) as a smaller food source.  I'll add the sieved other copepods too, but I think the parvocalanus will do the heavy lifting as a food source since they didn't seem to be able to catch the others so readily in prior attempts.

This should give me an idea if it's doable with the current setup, and will mark a shift back into copepods as the food.  Artemia are certainly an option, but it will be nice to have fewer kinds of cultures going, and the idea of something I can grow food for to sustain rather than just hatching out eggs is still appealing.

[Marley1083]

Just stumbled onto this and I'm glad I did. This is a fascinating project. Good luck

 

[DaJMasta]

The story of the last attempt is sort of a dumb one, I transferred the parvocalanus culture to the larger vessel and for whatever reason, it crashed, so I had to make the attempt on artemia and it went basically as before, they don't seem to be able to eat these nauplii.  I don't know why it crashed.... maybe I fed it too much the night before, maybe there was some sort of residue in the 2G tank, maybe just by stirring up any sediment the water quality went down and killed it off.

 

In any case, I bregrudgingly bought another batch, and in a very accelerated bid, have it to a little more than a gallon in volume after only a few days.  This time I'm focusing on dilution with fresh saltwater frequently and even more restraint on feeding and the color of the water I allow it to get to, and since I still see them swimming around, I fed the first batch (one cup of the relatively diluted culture) to this batch of mandarin larvae that are 2.5 days old.  I got two days of spawns, the second day was another big fire cleaner shrimp spawn which involved a lot of sorting to remove eggs and they're getting artemia in a different vessel, but I intend to add some non-parvocalanus copepods to the group this evening (72 hours) that get through a 250um sieve, and each morning a portion of parvocalanus, adults and all.

I don't know if the culture's production will be high enough, but I'm glad I'm finally able to try it.  Just from observing the copepod's movement in the culture, they do seem to spend more time resting and have motion more similar to artemia - shorter, more predictable pulses - which I think will go a long way to them being easier to catch, but then also smaller and maybe better suited for their very small mouths.

Good luck to the new little guys!

[DaJMasta]

Today is day 3 post hatch for the newer eggs, and 4 post hatch for the older ones, and I've now fed them parvocalanus twice, apocyclops sieved twice, and tigriopus sieved once.  While their behavior is basically the same as previous runs, and they look fairly slim in profile from the top, under a microscope their story is going decidedly better:

 

 

 

Of the three larvae I got in this little vessel to look at, all three had pot bellies with something a distinctly different color in there.  One was hunting, one was only moving a little when something passed by, and one was basically drifting with very occasional fin movements, but with a mouth it didn't seem to be able to fully close around its catch.

It's a tiny step on their journey and most of it is still ahead, but from this observation, I think this batch has a decidedly better outlook than the last few already.

[lowsingle]

Once again, great work!  I just read this for the first time…..great details provided.  Thanks for keeping us posted

 

Darren

 

[DaJMasta]

I haven't stopped, but many delays, remaking of kreisel vessels, low spawning frequency, etc.  Rather than try to detail the last couple months, I'll sum it up quickly:"

Made a new kreisel with a cone shaped base and a tube for air bubbles for very low flow - while it works as intended, apparently a cone bottom is a death sentence for mandarin prolarvae - I don't think I had one live to the point where they were able to start eating.

Made a new, new kreisel (term used loosely) with a flat, wider bottom and dark, shallow sides.  Found out that leaving a side open to light is also bad for them, so now it has a light blocker.

Had a couple months of 1-2 spawns a week (mostly 1), but frequency has jumped up again this past week, no change in diet or tankmates to trigger it really.

Have a couple larvae alive right now, and a few prolarvae, with more on the way, but no big success as still only apocyclops and tigriopus pods as food - though a new sieve size lets me feed them exclusively 45-100 micron foods (may be helpful, size seems to matter a lot for many larvae).

Lots of trouble keeping parvocalanus going, lost the cultures after 2-3 months of moderate production turned barely sustainable.  I have a better grasp of it and a better sense of what I need to do, at least part of the last culture's failure was contamination of my chaetoceros and isochrysis cultures.  Both have been restarted and are growing in, so the foods provided should be edible for them again.

Anyways, I also got a fancy new microscope that I'm starting to put through the paces and learn how to properly use.  My first live specimen was three mandarin eggs from this evening's spawn - one unfertilized - and this short timelapse was taken over about 25 minutes, from 50 minutes to 75 minutes post spawn.  They go from 4 cells to 16 in that time!

 

[lowsingle]

Nice!  

[DaJMasta]

A small update with potential for real progress:

I got a spawn a couple days ago and stayed up all night to try and get a timelapse of the egg development.  I ended up losing the eggs in the video, but only after quite a while of keeping them going, I'll probably make another attempt when I can refine the method a little, I think either the flow (complete lack of it) wasn't sufficient to bring enough oxygen to the developing egg, or maybe I added too much freshwater to the slide well and caused enough osmotic pressure to injure the developing embryo (adding ~50uL of RODI 2-3 times an hour.... being an ATO for a few drops of water is a challenge).  In any case, the timelapse still looks pretty impressive, from the first cell division to well into the point where you can tell it's a chordate (like us!)

 

Then today, I took a little video of the larvae trying to hunt, since their first feeding was this morning:

And the most promising part: I finally have a parvocalanus culture going with some density and stability.  It turns out, my basic method last time was correct, but my isochrysis and chaetoceros algae cultures were contaminated, so the food I was feeding was only partly edible for them.  I've had one culture going for a couple weeks, more stably than before, and in 6 cups of drained volume, has several dozen copepods, minimum, and most of them fit through a 250 micron screen.  I've also got a second culture that's about 3/4 grown into the container, and the feeding today was the first feeding from the new cultures.  Not sure what the final density will be for the culture, but I will keep after them and will drain it, scrub down the sides, and refill if I see a buildup of mulm that appears to have a negative effect.

[lynn.reef.nerd]

Some excellent work you are doing!

[DaJMasta]

I tried a few more rounds after this in the little in-tank spawning vessels I had made, and even when fed parvocalanus, I wasn't getting much better results than with apocyclops earlier, they simply weren't lasting to the 1 week mark.

 

So I decided I would try a new method: their own tank with fresh saltwater to start it.  So I set up a 10G brute trashcan with saltwater, some low power heaters, and a small airstone in the center with a light over the top and waited to see what would spawn in the tank (I've only got one, so only one critter at a time).  The mandarins spawned this evening, both a pretty large spawn and eggs that somehow look slightly larger than usual, so while the approach is entirely new and I'll be trying with apocyclops nauplii since my parvocalanus cultures took a pretty big hit over the vacation, I'm curious if giving them a LOT more space and depth make a difference in how they grow.  It seems like basically every successful breeding operation uses larger containers than I do in systems started from sterile water, so it's high time I give that a shot.

[DaJMasta]

The new vessel is having the desired results

 

 

The current setup is:

A 10G Brute trash can

3 low power, always-on heaters stuck to the sides

An airstone set low in the center

A low power tank light mounted a little more than a foot off the surface

 

And the feeding regime has been:

from the second day post hatch (2.5 days post spawn), add apocyclops copepods sieved through a 200 micron screen, twice a day (morning and night)

from the third day, add 50mL of phytoplankton once a day

Right now, there are extra pods in the vessel, so I will reduce feeding somewhat (and increase phytoplankton addition somewhat) for a couple days to sort of co-culture them until the larvae can reduce their population.

Right now, counting them is very tough (they spread out and are small), but I probably have a dozen or so.  They have spread out in the water column and regularly slink around the bottom or the sides of the tank, but still come out into the center of the water.  They're noticeably better swimmers than the younger larvae I had worked with before, and they have a much more sensitive escape response.  When looking up close, these guys have pot bellies and are very active, plus they've started to get just a little bit of red in their coloration.


I haven't had any live to 6 days before, and I have several and they appear healthy.  The extra space (and maybe starting with sterile water) has already had a marked positive effect.

[lynn.reef.nerd]

[YHSublime]

Love to hear this. You probably don't hear it enough, but kudos to you for trailblazing at home, I barely have the patience for the basic stuff!

[DaJMasta]

I've got three, I think, and they've turned slightly reddish though they still look mostly yellow under the microscope.  They seem to be acting more calm/coordinated, I even spotted the one under the microscope doing that funny mouth stretch thing dragonets do.  They still mostly swim freely, but I do see them prowling around the surfaces too, somewhat closer to the adult behavior.

I saw another account of raising them (a short video in french on youtube showing some larval stages), which seemed to indicate they settle around two weeks... so maybe this coming week?!  I don't know if flexion is a thing for mandarins, and I know the last metamorphosis of larval stages often has one of the highest mortality rates.... but they're doing great so far.  I also got a couple new species of copepod in this week and am spinning up the cultures now, so I hope to have more food variety for later attempts.

 

 

[DaJMasta]

Two weeks post hatch!

 

I think I'm down to two fish, but they appear to be healthy.  They mostly are free swimming still, but you can see in the light glare in the more zoomed in footage that they have their pelvic fins that will be used for perching, and I do see them occasionally on the side of the container.  They've also got a wider head/body than a few days ago and they seem to spend more time looking around for their prey than actually chasing after it (and the eye movement seems to track copepods well).  I got my hands on a paper describing raising them and their development, and while settlement has been reported from 14-20 days, there's a suggestion that lower pelagic food availability could contribute to earlier settlement, so since they should have plenty and it's all in the water column, I'd expect they're a few days from settling and acting like adults, but they seem to be basically equipped to do so now.

If you look closely at their patterning, the red pigment that had developed earlier really looks like the adult patterning, just not in the right colors, and I suspect it's sort of a precursor to that.  It looks like while they should settle in the next week, it will take 40-45 days to start really changing color (first blue and then some green), and around day 50 should be when they actually have their adult coloration.  I will have to make a best-guess as to when to move them into the main tank, but I'll shoot for 3-4 weeks, both to get them a bigger variety of food sources and to free up the trashcan for a run of something new!