Yellow banded possum wrasse breeding attempts

[Biota_Marine]

This is incredible work! We'd love to follow along with this.

About 8 years ago some of the students at the UF TAL facility were getting some spawns in their personal tanks but also didn't have much luck with larviculture. I assume first feeds are going to be very difficult given the small sizing. You may need to culture some ciliated protists given their small size (20µm-60µm) pending on their initial mouth gape.

 

[DaJMasta]

Much appreciated, I've been avoiding culturing rotifers because of their penchant for spreading and my relatively small operation (the copepods and phyto are grown on a shelf in my kitchen ), but I may be forced that direction. Though maybe I've got some ciliate contamination in something else I can make use of...

I've got a 25 micron mesh sieve, but I avoid using it because even with 2x the surface area it drains so, so slowly (tapping the sides/pulling through water with capillary action is still only drips per second), but I may slap it on the stack I try feeding them first to see if it catches anything smaller.

I do think the gape will be small - I remember the first larval stages of the mandarins had a sort of folding jaw that let them grab something almost as big as their head, and from the view I got of the last batch, these guys don't seem to have the same benefit.

Hopefully tomorrow they'll be willing to try to eat and I'll be able to try introducing various sized feeds under the microscope. The plan right now is 45-120um sieved copepods around 48 hours post spawn this evening, then checking in the morning to see whether they've managed to eat anything.

The larvae are all still right at the top of the water, but they occasionally swim in mostly a straight line for a few centimeters. Doesn't look like hunting strikes to me, yet, I think they're just learning to swim.

 

[ISpeakForTheSeas]

Super cool!

I do think the gape will be small - I remember the first larval stages of the mandarins had a sort of folding jaw that let them grab something almost as big as their head, and from the view I got of the last batch, these guys don't seem to have the same benefit.

Yeah, given the 20% gape rule:

-Larval fish can typically only eat feeders that are approximately 20% of the size of their gape; this means that the smaller the larval fish are, the smaller their feeders need to be.

And, your pics of the larvae with phytoplankton for scale, I would guess you'll end up needing ciliates and/or first instar nauplii from one of the very small pod species (such as Parvocalanus crassirostris, Oithona colcarva, Gladioferens impairipes, or Bestiolina coreana) to use as a first feed these larvae.

While small, rotifers are still much larger than the first instar nauplii of these kinds of pods (with Reed Mariculture reporting newly hatched S-Strain Rotifers, Brachionus rotundiformis, being 85 microns and another source reporting 90 microns):

Adult Parvocalanus pods get up to 400 microns, whereas stage 1nauplii are about 40 microns. This means that they should be ~1/10 the size of the adult pods (which looks like it would fit with the ~20% gape rule). So, basically, before offering the feeders to the fish, strain them through a 45 or 50 micron mesh - this ensures that you're only getting the smallest available feeders (those that are small enough to fall through a 45 or 50 micron mesh), which should be more appropriately sized for the larval fish.

For a source to support the gape rule:

"most marine fish larvae consume prey that are only 20% of their total gape."**

**Source:

Spawning, early development and first feeding in the gobiid fish Priolepis nocturna

Spawning, early development and first feeding in the gobiid fish Priolepis nocturna

www.academia.edu

Definitely keep us updated on this - the more info you can find, the better!

 

[Arkayology]

Wow! Very interesting! Following!

 

[Fapman]

This morning, I may have fewer, but I know I have some, and I know they're trying to eat. I fed 58-150um sieved copepods last night shortly after the post, and underestimated the one in the cup, so I probably fed too high a prey density, but they seem to have continued to descend in the water column, so they're just harder to see than before. I know there are at least two, I've seen them try to eat the copepods under the microscope, but also don't see a belly on the little guys.


I think I will try 45-125 or 58-125 micron sieves for later feedings because the larger copepods getting through the 150 screen definitely still appear to be too large. I think it's a copepod nauplii and little larger sort of situation.

Wow. I’ve only seen these fish available as wild caught. I have a yellow banded also. I want to purchase the red variant for another tank I have.

 

[DaJMasta]

Well there's news, but the most important one is not as confirmed as I would like it to be.

The news: they have a developed digestive tract MUCH earlier than I estimated. This is a mere 43 hours post spawn (about one day after hatching):

The black dot on the bottom is the air bubble, the area behind it is the remainder of the yolk sack, but running along that side of the spine is a thing, varying width, darker area with a tiny vent about half way back. In this image from the big boy scope, you can see the head is nearly stuffed with intestines too!

What's more.... since they had a digestive tract, I added a few drops of 45-120 micron sieved food... I thought I observed a strike after about a minute or so of reacting to the new movement, and then I didn't observe a strike in this one or the other in the well with it for 10 minutes or more. This is from after the strike:

Now this could be a different larva, since there was two... but that front area looks more bulbous. I wasn't able to confirm eating without a doubt, but it sure looked like something happened.

So this evening I went back to them, at the same 52 hours or so post spawn I had images from the last run, and I took some more video. They looked like this:

Eye development that was very different from just a few hours earlier, and it looks like the beginnings of its skull! But was it eating.... was there something in the gut?

Truthfully, I still can't tell, but also truthfully, the earlier image from 52 hours post spawn looked more slender and more straight than this more lumpy, slightly thicker in the front larva. I'm going to feed the same size again and then see what they look like in the morning.

 

[strich]

I've thought for a while now that the next tank I make would have an overflow with a big overflow box, so that I could set in a mesh basket (solid bottom with small lip to retain some water). The basket may even need to be pleated to maximize surface area (and minimize crushing suction force against the mesh), but a lower return pump setting in the evening would probably help. The eggs are still slightly buoyant, so if they don't get eaten, something like that could automate spawn collection.

Of course, that still means you need to move them to other vessels to raise them, but that was sort of a given.

mmm interesting. For me I've always been curious about whether a series of main tank addons could be engineered and used by the community eventually. For the inverts you'd already created the auto attracting light attachment and basket which I thought was really cool. Maybe in this case a basket that lives in the sump after the overflow box on most tanks could work, since I think most overflows on main tanks are slim and probably not easy to add anything to. I dunno if the force of fluid landing in the sump would have already smashed the eggs though.

PS I love the participation from @Biota_Marine and other experts in here - This is what I think the hobby is all about!

 

[DaJMasta]

Spent a couple of hours in total behind the microscopes today, still hard to get good images, and while I think I have some good info and some progress overall, I'm not sure it's looking rosy for the current batch.

This morning, the larvae looked active and mostly at the top of the container, so I got them under the scope:

And while they look more developed, act like they have control over themselves, and appear to be ok from the macro level, they don't look like they have full bellies and don't really look much thicker than the ones I saw in the previous run. On a side note, I wonder what the plates behind the eyes with the pair of round things are - maybe beginnings of gills?

I figured I would check the group that was spawned the day after to see if I could narrow down when the gut formed, and at 39 hours, it looks like it's already there! This is their head around that time (the pictures that included the gut never had much of the animal in focus/in frame, but I did see that characteristic shape behind the yolk (the bump on the left with the bubble at the front)

Since they had a gut, I went ahead with feeding, trying 30-100 micron sieves this time. The amount of food that got through was much, much lower, and the draining speed of the 30 micron sieve was so slow as to be nearly unusable. From what I saw, there was only nauplii getting through in this batch, but it probably wasn't from all four species of copepods I've got going.


When I returned to examining them in the evening, at hour 75 I still had at least a couple dozen - a marked improvement from the first run, though there were a few I could see dead on the surface. Under the microscope, they're further developed, but still thin, still without obvious stuff in the gut. I'm not sure there will be many left tomorrow morning even though there are a number left now.

So if I have them tomorrow, I will continue to feed them 45-120 micron sieved copepods, and maybe if they got some initially, they will be large enough to eat more, but I can see a pretty high density of larger copepods in there now, which could also be interfering with finding prey they can actually eat.

I need a new food. I don't really want to do rotifers, but I have a vial of frozen eggs that's several years old now that I think I will reconstitute and just keep in a different corner of my place and see. I've also got an idea to get the turkey baster to get a few squirts of water out of my tanks in cryptic zones near muck, put it through a 100 micron sieve, add a little phyto, and see if anything grows. Could be a good way to harvest ciliates or other small organisms that can perpetuate in tanks, and if they can maintain on phyto, their feeding/maintenance should be manageable in the longer term. I have a feeling a small food source is going to be a key piece to this puzzle, even if its only needed for a few days until they can manage the larger copepod nauplii.

 

[strich]

Thanks for the update.

This might be a dumb question, but might something basic like an Aeropress help with seiving through tight filters? I imagine there is a pressure limit to what copepods can take but its got to be better than gravity-fed filtering. Either way sounds like finding a better solution there is going to help more than just one of your projects.

 

[DaJMasta]

I don't know, really. It would certainly increase flow (and today I actually sealed the top of the cup around my face and blew to make some pressure), but I do presume it injures what's trapped on the mesh. I think the better option is just increase the height of the water above it, though that probably causes a similar pressure issue, it means that the last few dregs of water in the bottom contain more organisms. It drains at an ok speed at height, but my problem is that it gets to the last inch or so of water and really slows down to almost nothing without pressure or manipulation, and if I only have one cupful of water into it, that's just not a very concentrated feed. At the moment I don't really have enough culture volume to do that if I'm feeding several times a day, so I'll have to consider.

 

[Biota_Marine]

Thanks for the update.

This might be a dumb question, but might something basic like an Aeropress help with seiving through tight filters? I imagine there is a pressure limit to what copepods can take but its got to be better than gravity-fed filtering. Either way sounds like finding a better solution there is going to help more than just one of your projects.

Forcing through can sometime damage the nauplii and a big part of them being prey items is the movement associated. It's going to sound crazy but if you have like a theragun or similar device the vibrations help things move through the sieve faster, I used to do that when I was home breeding

 

[F i s h y]

Forcing through can sometime damage the nauplii and a big part of them being prey items is the movement associated. It's going to sound crazy but if you have like a theragun or similar device the vibrations help things move through the sieve faster, I used to do that when I was home breeding

what an interesting idea.

 

[DaJMasta]

Makes sense. I've just been tapping the side of the mesh to keep the particles more suspended and less clogged, but in particular for the <45 micron sizes, holding my fingers against the mesh and letting the surface tension of the water draw it through the mesh seems to make a noticeable improvement to. I imagine lots of small vibrations probably does a better job still.

Will see what they look like under the microscope now, but while there are some more mid water and this was probably a bad sign in the last run, I see more than a dozen this morning, going into their third day post hatch.

 

[DaJMasta]

There were some this morning, and I got some pics direct from the microscope showing their development. 88 Hours post spawn, the biggest difference was the appearance of pectoral fins:

Harder to see in the first image, but that one is slightly laying on its side, the mouth is facing to the left (the slightly raised, flatter area on the head). The framerate from this camera is low, but I got a few frames of the mouth opening and closing a little - it's the only way I could tell we were looking at the left cheek.

A few hours later, I caught another larva and looked at the other microscope, which I hadn't checked around 88 hours. So this is 90 hours in:

The pectoral fins definitely look more pronounced, and you can see the eyes have entirely silvered over (they're not very useful if they let in light from all sides!) At this point in the day, I only had seen a few swimming around near the top, and since they are still quite slender, I wondered if I would see any when day 5 post hatch begun in a few hours. They were also more shy about lighting under the microscopes - I ended up lowering the brightness considerably to get them to stop trying to just get out of the way or hide in the corner quite as much - those eyes are getting used.

I returned home in the evening and checked with a flashlight... and saw more than a dozen past the start of day 5 post spawn! Apparently the larvae are retreating from the surface during the day, probably due to the light. Makes them harder to see/catch during the day, but the longer they can survive, the closer to eating the food I can provide they get!

Those two are from slightly after midnight this evening, so a bit past 100 hours post spawn (and more than 80 hours post hatch). The pectoral fins seem to help them stabilize their trips, so their swimming paths are a bit straighter and smaller movements seem to have more control. Haven't witnessed an eye movement nor seen any full stomachs yet, but they're still developing well past the first run.

As a bonus, that mandarin egg comparison wasn't just for show, while I only got a few larvae out of a comparatively large spawn, this little guy is a 4 day post spawn mandarin larva, under the same magnification as the above two images. He was flexing his (much larger) mouth continuously when I was looking.

 

[DaJMasta]

They've made it into their 6th day. Still small, still looking thin, and I did lose at least a couple today, but several still remain. Instead of more stills and descriptions, how about some video?

A little over a minute in, the second larva is on its side more, and I believe on the topmost part around then you can see its belly somewhat inflated - still completely clear, but I think probably the reason a few are still going. In watching them, some nauplii still look too large to eat, but there are some nauplii that appear about the right size. I think at least one of the copepods I'm raising starts small enough to be edible, but I'm not sure which and I likely don't have enough of it to supply sufficient food density for a run.

I've got the frozen rotifer cysts hydrated, but I haven't seen activity in there yet, so I will see how quickly the new food can get off the ground. The salinity for this species seems to be quite a bit under my normal salinity (15 ppt vs. 35 ppt), I think it's idealistic, but if I can get them going, that may actually reduce the risk of contamination somewhat, though I still plan on keeping them in a different room and using only different tools.

Looks like I collected a large spawn of new eggs today, maybe close to a hundred!

 

[F i s h y]

They've made it into their 6th day. Still small, still looking thin, and I did lose at least a couple today, but several still remain. Instead of more stills and descriptions, how about some video?

A little over a minute in, the second larva is on its side more, and I believe on the topmost part around then you can see its belly somewhat inflated - still completely clear, but I think probably the reason a few are still going. In watching them, some nauplii still look too large to eat, but there are some nauplii that appear about the right size. I think at least one of the copepods I'm raising starts small enough to be edible, but I'm not sure which and I likely don't have enough of it to supply sufficient food density for a run.

I've got the frozen rotifer cysts hydrated, but I haven't seen activity in there yet, so I will see how quickly the new food can get off the ground. The salinity for this species seems to be quite a bit under my normal salinity (15 ppt vs. 35 ppt), I think it's idealistic, but if I can get them going, that may actually reduce the risk of contamination somewhat, though I still plan on keeping them in a different room and using only different tools.

Looks like I collected a large spawn of new eggs today, maybe close to a hundred!

This seems highly encouraging. Keep it up. I'm looking at 3 weeks before I can try fridmani pseudochromis and sprigeri damsels again both of which require smaller than standard rotifer cultures.

 

[DaJMasta]

Beginning of day 7 (post spawn) and I'm down to 3 or 4 of the starting 4 dozen or so. They feed mostly midwater and they still look like a tiny reflective dot with a tail. Under the microscope, not too different? I think I saw a little twitching in one eye, but I suspect it was a result of jaw movement rather than actual control of the eye.

The eggs collected yesterday started hatching around 3:10 pm (18.5 hours post spawn), and of the largeish group I collected, I probably only got about half to hatch. This evening I took a piece of paper to clean the grime off the surface (as before), and afterwards, I see some dead. I wonder if I need to wait longer before cleaning off the surface, but it really does make a big difference in being able to see them. It's pretty difficult to remove the grime from the surface before they hatch on account of the tiny, floating eggs.

 

[braaap]

Remarkable imaging. Hopefully you can figure out the food sizing. Probably rotifiers are the best option as they are a smaller initial size arent they?

 

[DaJMasta]

Well, sad news. I woke up today and couldn't find any larvae. They made it into day 7 post spawn, but not through it. Twice the length of the last major run, and with some limited success, but I'll have to try some more.

I had another spawn collected that passed into the start of day three today, and I'm trying a slight variation. I'm feeding 45-100 micron sieved copepods, with the hope that using larger quantities of copepod culture will boost the number of nauplii that get through the 100 micron sieve and have enough to feed them. While I see them getting through, the density is really massively lower than using the 120 micron sieve, and I haven't really observed them faring better or having food in their stomachs any better than the more crowded feeding of the last, most successful run. I had one under the microscope and got a well in focus mid section and a bit higher framerate to see movement.

The plane of focus is basically the cloaca... but you can see some texture and form to the spine (seems like their spine is the upper and lower more sturdy parts and a channel in the middle which should become the nerves.) Something I've observed in all of them but haven't noted on: the bumps on their fins. There are some on the interior area, but also a trail of them at the end. The ones on the end are most visible, and they seemed almost aligned like rays, but I don't think they really have a ray structure. I wonder what their purpose is - maybe sensory?

In any case, my attempted rotifer culture is 4+ days old and I can see basically nothing. If I can't at least see some under the microscope tomorrow, I'm just going to order a live culture, the cysts may have been too old and I really want a smaller food to have a better shot. I also pulled a bit of water and muck out of the more cryptic areas of my tanks, ran it through the 100 micron sieve, and mixed with a little water and a little phyto. The idea is that if I put whatever I catch in there with conditions for food I can maintain, if something hunger games's itself into a colony, hopefully it will be small enough for them to eat. that probably means running it through the same sieve every few days for the first week or two - we'll see if it amounts to anything.

Also collected another batch of eggs, and this attempt will be in a bucket. I've run into other larvae before that can do reasonably for a few days in an in-tank basket but then seem to die off, and while I have my doubts at being able to saturate the larger volume, I'll leave the starting water level low, I'll feed with the 120 micron sieve again, and hopefully a little more space to stretch their fins and a lower prey density helps them catch a meal and survive.

 

[DaJMasta]

Small update: The first bucket experiment I can call unsuccessful. They hatched out, but I've seen my highest mortality rate yet in a first day - I think a single bubble per second on the air in the center of the bucket is enough to injure them. I think I could try to get a smaller bubble, but I think the better approach will just to be to do subsequent bucket runs with no aeration for a few days whatsoever - this is more like what it's like in the baskets, and with much more surface area and natural currents from the heating on the side, there should be enough gas exchange at least until they start getting a bit stronger.

In related-to-attempts news, I finally have a confirmed rotifer. On the fifth day, I've seen a few specks moving around in the culture, and this L strain rotifer will hopefully reproduce fast enough for me to start harvesting it a little within the week:

I left the image uncropped, because the images I took of the larvae today (start of day 4, the batch being fed 45-100 micron sieved copepods) is at the same magnification, so the size comparison is one to one. The short story for rotifers - fully grown adults are probably still too large for them to eat.

Side view, I still see the bubble, but you can see some texture to the gut too - and it doesn't look empty, though I don't see big chunks in it. This guy was feeling photogenic once I turned the brightness on the light down, it would hide near the corners of the slide wells (in the shade), but with the light down it was much happier to stay in the center of the slide with time to snap pictures. From the side, you can actually see a bit of a pectoral fin - small, but already developed around the start of day three post spawn:

And those images are half dimension still captures from the camera, whereas most of my images so far are much less sharp and noiser because they are 1080p video captures of the camera application, but it wanted to be more vertically oriented then, so I'm including one too:

Honestly, it could just be the fins slightly side on, but this is the thickest around they've looked so far.