Surprise! Masked goby eggs found when cleaning tank - any tips?

DaJMasta

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I went to clean out a 3d printed sort of kreisel shape that I was trying to raise shrimp larvae in, and behind the light blocker on the outside of it, there was a mass of eggs. There are a few fish in the tank it was in, but the only adults where there were more than one fish are masked gobies, and as a best guess given the others, that's my tentative ID.
masked goby first eggs.jpg


I'm pretty well setup for an attempt at raising the fry, but I was wondering if anyone could offer any specifics on some of the basics: preferred foods, flow/space requirements, and fry behavior (how they strike, whether they gather in a certain way, how attracted to light they are, etc.).

I managed to find a vessel where I could keep them as they hatch without trying to scrape them off the light blocker (physically large), and best I can tell, many are fertilized but were probably deposited on different days, since there are clearly some near hatch as well as most at much earlier stages. I've also got a bubbler going by them for a bit of circulation, and I'll see when things hatch, but what sorts of foods do you think they will fare best with? Do I need to block out all light from the sides (seems important for some larvae)? How long from hatch will it take for them to eat, and how long of a window do they need to eat within? Any benefit to offering phytoplankton?

My preliminary search for info says hatch time is around 6 days, but as said, I wouldn't be surprised if larvae were free swimming tomorrow. Exciting! And hopefully not an isolated incedent (though I will need to find something else they can spawn on), but since I've got a setup basically ready to go, if someone can lend their experience, I can give these little guys the best shot from the get go.

I've got apocyclops, tigriopus, and a very limited supply of parvocalanus available as foods, as well as all the small TDO sizes and live phytoplankton. I've got a few size and shape vessels with full light blocking from the sides and dim overhead, always-on moonlights. I think my basic approach will just be feeding whatever I can in a shotgun approach, though only smaller copepods that will fit through a 250um screen, maybe starting as soon as I see some hatch.

masked goby egg zoom.jpg


As a reference, those lines behind the eggs are the layers of the 3d printed part they're on, and my settings were 200um layer height, so these eggs are less than 1mm in diameter, and the larvae will probably hatch out at around 2mm long (which is consistent with the info I found).
 
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vetteguy53081

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Unless fertilized will become fish food
 

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Unfortunately, this is one of those species that has been cultured successfully, but much of the culture info is likely a trade secret (and the info on their original culture in the 90's is now unavailable to the public on it's original site, though you might be able to dig it up somewhere - the link I list below is a good starting point though). So, these are my best guesses/suggestions to try and help (sorry if they're bad/wrong).

For foods, here's what ORA (who has cultured them) said about feeding them:
"They simply would not accept rotifers as a first food. It wasn’t until Todd started to offer a small ciliate that he succeeded with this species. Here at ORA we offered the larvae cultured copepod nauplii under 75(!) microns and we were pleased to see them settle out around 30 days post hatch. While small, these fish are pretty quick to mature, we were amazed to see fertile spawns produced by individuals of this species that are barely 100 days old!"

This means that you'll need to feed them Parvocalanus nauplii (unless you have tiny ciliates to offer, but, in my experience, those are very difficult to come by these days), though you might be able to offer some newly hatched Apocyclops nauplii too. Either way, unfortunately, the 250 micron mesh is likely too large for the need here (though it was a good idea).

A lot of species begin eating the day they hatch, but several species don't eat until day 3+ post hatch. If they hatch with a yolk to support them, most fish go through those in 3-5 days (and then they starve either that day or shortly after), so I think offering them food the day they hatch would be wise. The good news in the food category is - based on your photos above - you can get a close look at the larvae to see if they are eating, so that should really help figure to out what they need and if you need to offer bigger/smaller or different foods.

With the phytoplankton, I doubt they'd really see any benefit from offering it to them directly, but you can offer some if you want to. With the TDO, if it's TDO-A, it's likely to be appropriately sized for them a few days/weeks post hatch, but they probably won't eat it until they've settled (most fish fry need live feeds because the movement it what draws them to eat it).

Now, for your other points.

With flow/space, I'd guess low flow (probably not more than the bubbler you've got in with them), and I'd honestly guess you wouldn't need more than a 20 or 30 gallon tank to raise them in (cylindrical is better than square/rectangular, as kreisel style tanks are the best we know of so far for raising young, but if the rectangle is big enough and the food is circulated well enough the shape doesn't matter too much). Obviously, the bigger the better, but I'd guess those would work for a minimum tank size. You could potentially go smaller, but some fish (like Sergeant Major Damsels) fail to settle and die out if the tank is too small.

For fry behavior, I honestly have no idea for these little guys - sorry.

For the light, I'd guess to keep it dim, but probably not blocked out entirely. I'd wait to slowly ramp up the lights for until they've settled or are nearly settled, and then bring them up to normal reef tank levels.

That's all the advice I can think of. Hope it helps!
 
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Thanks, that food info is particularly helpful. From a short video I saw of some eggs not yet hatched, the fry look fairly fully formed, so I think the assumption that they can eat shortly after hatch is probably the right one. I mentioned a 250um sieve because it's sort of a default, but I've got finer sizes to use, so I will see how low I can still get food through. I think I've seen apocyclops at least under 150um, but their swimming behavior has made them hard for other larvae to catch (mandarins, lysmata shrimp). Parvocalanus is the right choice from all the descriptions I've seen, but I've really been struggling to maintain decent density in my cultures, so while they are again slowly regrowing, I don't know if I'll have sufficient food for growing fry.

Hopefully I can offer them some small stuff, then transition them to larger ones which I have available in more quantity.

I will have them in a shallow dark sided vessel with low light over the top, but it will be much smaller than 20-30 gallons! I just don't have the space to try and maintain that, and while I think this has had negative effects on runs I've tried so far, it's what I've got, so it's what I'll try. At the very least, the smaller vessel size means a higher concentration of the limited food I've got.

It's also been my experience that TDO is really only accepted after the early stages - I think that it sinks somewhat quickly and that it doesn't move means really small fry simply don't notice it - but I will see whether they take it at some point - their parents seem to.

No hatching yet, but it's neat to see the eyes move around slightly even when the flow is off.
 

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Thanks, that food info is particularly helpful. From a short video I saw of some eggs not yet hatched, the fry look fairly fully formed, so I think the assumption that they can eat shortly after hatch is probably the right one. I mentioned a 250um sieve because it's sort of a default, but I've got finer sizes to use, so I will see how low I can still get food through. I think I've seen apocyclops at least under 150um, but their swimming behavior has made them hard for other larvae to catch (mandarins, lysmata shrimp). Parvocalanus is the right choice from all the descriptions I've seen, but I've really been struggling to maintain decent density in my cultures, so while they are again slowly regrowing, I don't know if I'll have sufficient food for growing fry.

Hopefully I can offer them some small stuff, then transition them to larger ones which I have available in more quantity.

I will have them in a shallow dark sided vessel with low light over the top, but it will be much smaller than 20-30 gallons! I just don't have the space to try and maintain that, and while I think this has had negative effects on runs I've tried so far, it's what I've got, so it's what I'll try. At the very least, the smaller vessel size means a higher concentration of the limited food I've got.

It's also been my experience that TDO is really only accepted after the early stages - I think that it sinks somewhat quickly and that it doesn't move means really small fry simply don't notice it - but I will see whether they take it at some point - their parents seem to.

No hatching yet, but it's neat to see the eyes move around slightly even when the flow is off.
Yeah, stage 1 nauplii of Apocyclop panamensis are ~70 microns (which is why I said they might be able to be used when newly hatched), so if you've got a fine enough mesh, they could potentially work. Parvocalanus pods are notoriously difficult to culture, so I understand not having a large supply there.

I hope the rearing tank you've got works for you - I don't know if these guys are affected by tank size the same way some other species are, so it might not be a problem.

Keep us posted on how it goes!
 
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DaJMasta

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No hatching still, but those wiggles are certainly confirmed this morning:
masked goby eggs eyes.jpg

So many little eyes!

I also figured I would take notes on where they liked to spawn - the light blocker the eggs was on was just a few mm away from some mesh on the side of a sort of isolation basket/kreisel thing that I've been iterating on to raise things in an existing tank. Given the dark sides, the vertical orientation, and the relatively narrow spacing, I quickly designed a series of widening slots with a piece to hold them all together and provide shade. Less than 24 hours in the tank with the parents, and they apparently like it:
spawn stack in use.jpg

(sorry for the stringing)

While it's still maybe a little on the large side, it should be much easier to collect eggs by just pulling that thing out and placing it somewhere they can hatch out.
 

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I went to clean out a 3d printed sort of kreisel shape that I was trying to raise shrimp larvae in, and behind the light blocker on the outside of it, there was a mass of eggs. There are a few fish in the tank it was in, but the only adults where there were more than one fish are masked gobies, and as a best guess given the others, that's my tentative ID.
masked goby first eggs.jpg


I'm pretty well setup for an attempt at raising the fry, but I was wondering if anyone could offer any specifics on some of the basics: preferred foods, flow/space requirements, and fry behavior (how they strike, whether they gather in a certain way, how attracted to light they are, etc.).

I managed to find a vessel where I could keep them as they hatch without trying to scrape them off the light blocker (physically large), and best I can tell, many are fertilized but were probably deposited on different days, since there are clearly some near hatch as well as most at much earlier stages. I've also got a bubbler going by them for a bit of circulation, and I'll see when things hatch, but what sorts of foods do you think they will fare best with? Do I need to block out all light from the sides (seems important for some larvae)? How long from hatch will it take for them to eat, and how long of a window do they need to eat within? Any benefit to offering phytoplankton?

My preliminary search for info says hatch time is around 6 days, but as said, I wouldn't be surprised if larvae were free swimming tomorrow. Exciting! And hopefully not an isolated incedent (though I will need to find something else they can spawn on), but since I've got a setup basically ready to go, if someone can lend their experience, I can give these little guys the best shot from the get go.

I've got apocyclops, tigriopus, and a very limited supply of parvocalanus available as foods, as well as all the small TDO sizes and live phytoplankton. I've got a few size and shape vessels with full light blocking from the sides and dim overhead, always-on moonlights. I think my basic approach will just be feeding whatever I can in a shotgun approach, though only smaller copepods that will fit through a 250um screen, maybe starting as soon as I see some hatch.

masked goby egg zoom.jpg


As a reference, those lines behind the eggs are the layers of the 3d printed part they're on, and my settings were 200um layer height, so these eggs are less than 1mm in diameter, and the larvae will probably hatch out at around 2mm long (which is consistent with the info I found).
Wow....how exciting! Please keep us posted on their progress.
 
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DaJMasta

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They started hatching around 7:30pm on the 8th, at a slow rate, and the fry behavior is pretty active - stays in the water column, not extremely phototaxic, seems to be a reasonably strong and active swimmer and moves more or less continuously (presumably, no swim bladder yet). They have a little yolk sack around their neck, are almost completely transparent, and are maybe 2mm long - very small and difficult to see unless you're either looking for their shadow in a light or side lighting them. Actually one of the best indicators is when you shine a light in, you can see the little glint off their eyes - about the size of a copepod, just a point of light, but brighter than a copepod in the same light.
masked goby hatchling.jpg


The spawning was sort of a rolling event, one hatching every so often rather than all at once, and they kept coming into the night. I didn't have appropriate sieve sizes, really, so they were fed with copepods (apocyclops, tigriopus) that fit through a 120um screen and were caught by a 45um screen. I think this was a little too big for what they could eat.

Over the next day, there were more hatches, but also the first deaths seen - apparently they need to eat within the first 12 hours or so (that little yolk sack won't last long with their activity). I've tried catching a few to look and see if they've eaten anything, and while there's a chance, I have yet to be able to confirm food in their bellies, and they're actually quite good at running away from a pipette, making them somewhat hard to catch. This one looks thin and where the yolk sack was, while there's a bit of color, I don't think it's food.
masked goby no egg sack.jpg


This morning, the majority of the eggs in the clutch went white, there were a few the day before, but either the conditions for them developing aren't ideal or there was something on some earlier eggs that spread to others. There are still some eyes in eggs and still some hatches, but given that I don't seem to be able to feed them, this is probably about the end of this run.

I haven't seen new eggs on the little stack thing I designed, but one of the fish stays in it regularly and sometimes hovers outside the front side of it, so I made a new design that's slightly smaller and has less variation in gap width, centered around the wider sizes (the fish seems to prefer the slightly larger slots), and hopefully those can be methods to easily catch future spawns. Especially if attached to a plastic substrate like that, it could even be an option to dip in an antifungal or similar (not sure which, but I know this is done some) to prevent this kind of loss of eggs I'm seeing now. I've read through some parvocalanus culturing information and stumbled on another modification I can make to my process, so I'll see if I can get those cultures producing more reliably for future runs. I've also got a 100 micron screen on the way for better prey size sorting.
 
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DaJMasta

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Gave it another shot, and while there are no real better results, I'm definitely figuring out more about them.

The parents seem to like those sort of slots I made and one (presumably the one laying the eggs) will hang out in them regularly, with or without eggs. They also sort of guard the eggs once laid, and will commonly be hanging around near the entrance to the space, though I haven't seen them trying to chase off anything that came near - maybe just missed it.

The second batch took 5-6 days to start hatching, then a couple of days to fully hatch out - they don't hatch all at once. It was similar this time that the babies aren't swimming around more than 12 hours or so, but they can be seen afterwards on the bottom of the vessel (probably not a good sign, though), and it could be that the fry don't seek light actively... at least it seemed like when they ended up settling on the bottom, it was usually in a shaded spot.

I had something that was hindering my chaetoceros growth, so I tried feeding some of whatever it was to them, but it seemed to make no effective difference. I also had an amphipod hitchhike in on the thing with the eggs, so I may have lost some to predation as well. It will be a challenge to bring in clean eggs only, especially trying to keep out hydroids and the like, but at least in the vessel I'm currently using, there's basically no flow, so the risk of hydroids growing quickly is also very low.

Though not yet used, I've got a 100 micron mesh installed in a cup to sort copepods quickly and with a little finer granularity than before, and while it's gradually crashing and I will likely buy new in a couple of weeks, I'm trying another few tweaks to get a viable parvocalanus culture - it seems to be central to so many larvae I'm interested in raising.

hatched goby.jpg

That's actually two (one center, one a little out of the light beam to the lower left of it) that hatched out of the most recent batch. Shining a light in and looking for eyes or shining perpendicular to viewing is the only real way to spot them, the other dots are mostly sorted ( <150um) copepods.
 
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No luck, but more importantly, the parents jumped. I had three in a small tank that seemed to get along, and in short order after the last spawn the larger one chased the other two into jumping.

I've got a fine mesh lid on the tank now, and I've got three more that I've had for a month or so, but no spawns yet - they are all smaller, so it may just be a maturity thing.

I've also got a new vessel I'm trying for raising larvae - a 10 gallon brute trashcan - and I've been trying a couple of other creatures in there in between - with just a bit of success on another species. We'll see how things pan out, but I've been keeping notes and taking pictures.
 

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No luck, but more importantly, the parents jumped. I had three in a small tank that seemed to get along, and in short order after the last spawn the larger one chased the other two into jumping.

I've got a fine mesh lid on the tank now, and I've got three more that I've had for a month or so, but no spawns yet - they are all smaller, so it may just be a maturity thing.

I've also got a new vessel I'm trying for raising larvae - a 10 gallon brute trashcan - and I've been trying a couple of other creatures in there in between - with just a bit of success on another species. We'll see how things pan out, but I've been keeping notes and taking pictures.
I have 4 in observation currently. Got them from kpaquatics. Where did yours come from? I wonder if they will spawn in there and if not maybe in their permanent home. Theres 2 that are quite large, 1 a little smaller, and 1 tiny one. I think there is a good chance of a pair forming.
 

damsels are not mean

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That's where I got mine as well, I think the females are the largest ones, but they do need to grow in, so I'm not sure if there's a reliable way to sex them until they spawn.
If they're like other small gobies, they should all be protogynous. So juveniles are all female and eventually become male with maturity if the hierarchy allows it.
 
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