Fish Larvae

DerekG4

DerekG4

New member
I recently just found a tiny group (Not sure how many there are but there's more than 4) of fish larvae hanging around in a tiny hole in one of the rocks.

The strange thing is I don't have any fish in my tank that have a pair. The closest thing I had to a pair was 2 anthias, a pink square, and a silver streaked. About 5-6 days ago I noticed the pink square anthias died, hanging from under a rock. Don't know how it died, it was perfectly fine swimming around and eating. I had the fish for about a month and a half, I didn't buy anything that would have a fish in it, and the larvae are also near a spot where the anthias liked to be.

The other fishes that I have: Starry Blenny, Yellow Coris Wrasse, Yellow Tang, Blue Tang, Kole Tang, Mandarin Dragonette, Royal Gramma, and the other Anthias.

I know for sure these are fish larvae and not shrimp because 2 of them are just big enough to see their eyes clearly and it looked like fish eyes. They were transparent with a somewhat long body and one of them was already turning red (Which lead me to believe it was possibly anthias larvae). I'd take a picture but the hole their inside of is very tiny and they're just too tiny and fast for my iPhone's camera to focus. The biggest one is about a millimeter and a half long. The rest vary from half a millimeter to 1 millimeter. The only fish I could probably compare it in looks would be a glowlight tetra but instead of it having 1 stripe, they have 2. Now of course it can't be that fish knowing it's a freshwater fish.

Another strange thing is, they live in a hole where there's a small, half inch eunice worm. The worm doesn't seem to do anything, he just passes around them like they're nothing to him. I've been told if they're big enough they can eat small fish, but this worm is big enough to easily eat them which is what's weird to me.

Wasn't sure about posting this in the breeding forum or this one since I'm not exactly breeding any fish. Wasn't even aware that they were there until this morning. Either way, sorry in advance.
 
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I can't take a picture, they're too small for my camera to focus on it, all you could be able to see would be a tiny black dot with no characteristics.
 
Fish Larvae

Odd but exciting.
If they have Colour they've likely gone thru metamorphosis already. So maybe with a Seringe feed Rotifers , pods , cyclops near their hideout. Also you could submerse a bucket to collect the rock with the babies and put them in a 10 gallon to try and raise them.[emoji2]
 
What items did you add lately?

I doubt it are anthias as they are broadcast spawners who have tiny pelagic eggs and larva that are very unlikely to survive in a reef tank for more than a few minutes.

Half a millimeter, even one millimeter, is extremely tiny. Are you sure about the size?
Clownfish larva are 3 to 4 mm at hatch and about twice that size when settling down after about 2 weeks. Even dottyback and marine betta larva are not much shorter, just skinnier.

Most likely these are some crustacean (mysid shrimp, copepods,...)
 
Looks like you were right, 1mm is far too small. From the biggest one that I've seen, I made a rough estimate of 1/8 inch. I know for sure that at least 60% of the ones I seen are fish, they have normal eyes that look nothing like a shrimp's eye and If I use my flashlight on them, their eyes shine pretty bright.

It also appears it's not just 4 of them and they're not just on that 1 rock but they're actually on 3 rocks in a couple holes. So far I've counted 19 of them.

The most recent thing I put in the tank was a tiny rock with daisy polyps on them that I got from my neighbor. Didn't see anything unusual on it so I just acclimated it and added it in the tank. Second most recent was the 2 Anthias, which has been a month a half already.

I'll see if my dad's camera can focus on them better.
 
He has 2 blue tangs, a sailfin tang, a goby (Watchman goby I believe), a lawnmower blenny, a blue green chromis, a black and white percula clown, an ocellaris clown that has thicker black outlines (not sure what's the name of it) and a rock beauty angelfish. Can't be from the clownfish as I didn't see a single egg on the piece, the whole piece is only about an inch and a half long and half an inch wide
 
None of those fish listed have larvae that would be able to survive in a tank not dedicated to raising them and they would not congregate in a hole in a rock even if they were somehow finding something to eat. I can guarantee with 99.9% certainty that they are a arthropod of some sort, most likely a mysid.
 
Bongo Shrimp said:
... I can guarantee with 99.9% certainty that they are a arthropod of some sort, most likely a mysid.
Click to expand...

That's what it usually turns out to be in such cases.

Very few of the reef fish that make it to us are actually capable of reproducing successfully in a reef tank without human intervention and considerable effort.

The only ones I know of are Two Spot Gobies (Signigobius biocellatus) and Engineer Gobies(Pholidichthys leucotaenia). Banggai Cardinals and some of the seahorses with larger fry may also be successful if in a refugium with no predation and enough pods.

And then there are also sharks...
 
There have been at least a couple of threads just like this and every time it was mysid shrimp. If someone has never seen them I could certainly understand how they could think they were fish fry.

Derek do they look like this?

 
Nope, they don't look like that.

The ones in the hole have tail like that, but they're not that transparent. Most of the big ones have red or brown on them. Not sure if it's the video, but they're a tiny bit bigger than that amphipod in the video. They also move fluently and their tails move side to side just like a fish. Their eyes are white, with a black dot in the middle(They're pupil is completely round, not arrow shaped or anything, at least from what I can see at a quick glance), not completely black. If I use my flashlight, you can see their eyes shine pretty brightly. Some of them are taking refuge in holes near my zoas. Although I gotta check if they have tiny little feet or not. That's the only thing I haven't noticed.

I know I have a few copepods, lots of amphipods, and maybe a brine here and there. Not sure if I have mysis swimming around.
 
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DerekG4 said:
Nope, they don't look like that.

The ones in the hole have tail like that, but they're not that transparent. Most of the big ones have red or brown on them. Not sure if it's the video, but they're a tiny bit bigger than that amphipod in the video. They also move fluently and their tails move side to side just like a fish. Their eyes are white, with a black dot in the middle(They're pupil is completely round, not arrow shaped or anything, at least from what I can see at a quick glance), not completely black. If I use my flashlight, you can see their eyes shine pretty brightly. Some of them are taking refuge in holes near my zoas. Although I gotta check if they have tiny little feet or not. That's the only thing I haven't noticed.

I know I have a few copepods, lots of amphipods, and maybe a brine here and there. Not sure if I have mysis swimming around.
Click to expand...

There are many different species of mysids and they have different forms and somewhat different behavior. What you have could also, of course, be a different type of arthropod.

Since all of the fish you have in your tank have pelagic larvae, they would be unable to survive in a non dedicated tank and they certainly would not congregate in holes in live rock.

I would suggest trying to catch some with a turkey baster if possible. Might be tough though since most of the tiny pods and the like are very fast.
 
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