What is this?

[smoorman11]

This appeared overnight. Both of the corals nearby look ok. I added a firefish yesterday and haven't seen it since last night. Is it possible for a fish to decompose overnight? Also, The brown spots were blown off the rocks and settled on the bottom.

 

[Privateye]

Hmm. What's the texture like? Is it soft and gelatinous? Are there little specks inside it or is it completely clear?

I'm wondering whether it's some sort of egg sac. Some benthic polychaete worms have blobby egg masses, but usually you can see some tiny specks (eggs) embedded in them.

IMO it's not something you'd want to keep, so if it were me I'd remove it and look for clues. Either in the mass itself, or perhaps a tube in the sand from a benthic invertebrate.

 

[smoorman11]

Hmm. What's the texture like? Is it soft and gelatinous? Are there little specks inside it or is it completely clear?

I'm wondering whether it's some sort of egg sac. Some benthic polychaete worms have blobby egg masses, but usually you can see some tiny specks (eggs) embedded in them.

IMO it's not something you'd want to keep, so if it were me I'd remove it and look for clues. Either in the mass itself, or perhaps a tube in the sand from a benthic invertebrate.https://drive.google.com/file/d/1dxoI2qkDDjMLn6tMlQ4XiMzLi8Eu2VSy/view?usp=drivesdk

 

[smoorman11]

The top picture is the contents of the bottom pic. There was some kind of worm swimming in the contents but I'm having a hard time uploading a mp4 or GIF file.

 

[smoorman11]

This was swimming within the blob unless I picked it up while siphoning the blob. Roughly 2mm long.

 

[DSC reef]

This was swimming within the blob unless I picked it up while siphoning the blob. Roughly 2mm long.

That is a flatworm

 

[Privateye]

Well, I didn't expect a flatworm to show up in there, but it could be a good clue. Whether the blob was from the worm itself or it's just something the worm chose to associate with, flatworms are generally something you want to get rid of. Some eat euphyllia. I've only had to deal with the acro flatworms but this one looks different. Maybe larger, but maybe it's just the photo. It's still not as big as some flatworms get. It seems to be a lot more active than the acro flatworms. They didn't move around much at all.

I've dealt with the acro flatworms a couple of ways. Adding a spotted mandarin or six-line wrasse works for them, and I've had good success with Flatworm Exit. It doesn't kill every single one, but IME it killed over 95% of the population very quickly. The fish were required to take care of the rest.

While the same methods could work for these flatworms, if anyone has more-specific experience with these I defer to them. Perhaps some flatworm exit with a six-line wrasse would do the trick though. I know the big polyclad flatworms (some can get as big as your hand) can release toxins when they die but this was never an issue when we treated acro flatworms. Even huge infestations.

The presence of flatworms isn't usually an urgent issue. It's definitely something you want to address, but it's not like things are going to start dying overnight. No need to rush to the store before they close or anything.