Mandarin dragonet spawning log

[Origami]

The journey begins anew! I'm looking forward to your updates. We're all learning something from this.

[DaJMasta]

After feeding them, they seem to have congregated near the top, and between that and being more opaque, I think I've got more of them - maybe two dozen or so.

 

 

Also I've decided to use a 200 micron upper size limit for the food again because it turns out I just don't have a 150 micron sieve yet.

Edited February 8, 2023 by DaJMasta

[therootcause]

Checking in with you after several months.  Any spawning activity?

[DaJMasta]

Lots of activity, not a lot of success.  I can get larvae generally to day 5 or so and then they don't last, and that was a common early dieoff period before.

It could be feeding - my cultures may have been cross contaminated and I may not have the right copepods, but my current assumption is that I've been over feeding, so I've got some (maybe a dozen) at 2 days post hatch right about now, and will start feeding this evening, but something like 1/2 or 1/3 of the previous few attempts, and then emphasizing water changes with any discoloration of the water.

Lots of subtle changes to the vessels used and the overall approach, and then some delays from trying other things and just the time required to reset a vessel, which is now shortened for using smaller containers.  Hopefully I can find the right balance soon, but if nothing else, I've got plans to check and refresh my copepod cultures in the next few weeks too.

[DaJMasta]

I had been getting them to roughly 5 days post hatch and then they'd disappear, and I had seen it happen several times even when constraining the parameters pretty well, and last week I checked my copepod cultures...

 

The tisbe and tigripous cultures were apocyclops cultures, and the tisbe vessel also had some unknown white worms in it (non-segmented, all of 1-1.5mm long fully grown and <50um in diameter).

So I can pretty conclusively say that raising them on just apocyclops won't cut it.

Anyways, I've been making several changes over time, and in the next few weeks I should be ready to do runs with my improved setup:

 

I've moved to 3.5G brute buckets from the 10G brute trashcans - they're much easier/faster to restart or to water change, and by using the same plant warming mat around the outside, I can deal without an internal heater at all.

I've also designed 3d printed inserts to fully round the bottom corners of the bucket to streamline flow and reduce places for larvae to get caught.  I glue them in the bottom along with a sort of hyperbolic cone piece in the center which doubles as an airstone, so minimal impacts where the airlift happens and minimal stray things in the water column.  This may not do much for the mandarins, but I think will help considerably with the shrimp and higher flow larvae.

I'm also going to paint the inside of the buckets black.  I believe the opaque sides are enough to keep the larvae from having navigation problems (at least when the overhead light is a narrow diameter), and while I have heard of breeders painting the bottom of the bucket white to facilitate counting and such, the black bottoms of my buckets will make the nearly-clear larvae in the water column stand out more against the background when side lit with a flashlight - my preferred method of inspection.  Since the buckets are pretty shallow, I don't expect larvae being hard to spot on the bottom once they settle to be a likely problem.

I plan on doing weekly 80% or so water changes for every larva run, this is manageable with the smaller vessels even when draining through a siphon with a screen around it and should help reduce development issues associated with pollution.

To the same end, I will no longer feed phyto to the point of tinting the water, and will aim for just under that, as well as smaller doses of copepods in the first several days until I see adults swimming around in there, in which case I will reduce new copepod feedings to only occasionally and immediately after water changes.

I've also already started keeping logs for most spawns (I've been too lazy to get every one), but I have a basic format and space to make notes on their progress or observations - I have something like 18 logs for mandarin attempts already made since I started doing it, and probably more than that in logs for other species.  This should help identifying good techniques or chronic problems which otherwise go unnoticed in the day to day.

I've also made a few more sieves - I use specifically sized plastic (polyester, nylon) mesh covering a hole in a plastic 2 cup measure I cut with a dremel, and adhered with aquarium silicone.  They've proved to be remarkably useful and durable for collecting and sorting zooplankton, I've got sizes ranging from 20 micron to 500 micron, and they double as decent egg collectors.  Below 50 microns or so you probably want to make two holes (most of the area of the measuring cup) for double the mesh surface area as it can drain slowly.  Recent attempts have been made with copepods that are caught by a 30 micron screen and get through a 120 micron screen, but I have decent size control all the way up by swapping measuring cup sieves.

And finally, I've been using a new airlift powered larvae collector in the tank.  While it's not terribly efficient at catching a lot of what's there, it will catch some, and the removable collection baskets are great places to hatch mandarin eggs.  The current process is to collect the eggs in one of these containers, remove any hitchhiking things or debris with a pipette, then let the eggs hatch and get to about 2.5 days post hatch in the container with no real flow (and they're around 100mm in a cube), then transfer the hatched eggs (and not much of the unhatched ones or other stuff) into a bucket to start feeding them.


Constantly evolving process, and hopefully with the new tisbe, tigriopus, and acartia cultures coming online in the next week or two, some more positive signs should be on the horizon.  Once I can get some reasonable results, I'll have a lot of 3d models and things to start sharing.

[DaJMasta]

Well, they haven't been spawning often and there haven't been a ton of eggs, but I got a spawn just over a week ago that had maybe 15 or so hatch, and while I lost all but one, that one is still going, 7 days post hatch.

The difference?  Food.  I had started my new tigriopus/tisbe/acartia cultures the week before and just sieved a small amount of each with a 30um screen to feed to the new larvae starting 2.5 days post hatch.  Didn't feel like I had the density in the cultures to keep out the big ones, and probably still low for what they needed, but I'll see how far this little guy can get:

That other smudge in the second picture is a fully grown tigriopus copepod, to give an idea of scale.... they're even a similar color, you can really only tell from the slimmer tail and the different swimming behavior.  Gotta work on getting good focus with the camera, but neat to snap these from underwater in the bucket with it.

I've collected a few spawns since this one but have had none hatch out, but I will continue trying - I think my early on success rate will hinge on getting more, more controlled size live food, and I think my cultures are dense enough to actually be able to offer that now.

[nburg]

I'm just finding this thread. Your attempts are awesome! wishing you luck for these most recent ones!