Unknown microscopic worm

[SuncrestReef]

Last year my tank had a brown jelly outbreak that killed about 20% of my corals. At that time I looked at samples under my microscope and saw the Helicostoma nonatum ciliates commonly associated with brown jelly. It took about a month to get things cleaned up and my tank back to good health.

Today I saw symptoms of brown jelly on a hammer coral that's already lost about 3 heads. I took another sample to view under the microscope, and sure enough I found those same ciliates. However, I also found some much larger worm-like creatures swimming rapidly in the sample. Any ideas what they are, and if they are good or bad? See this video from a single drop of water:

 

[Miller535]

That thing is crazy looking!

 

[reef lover]

Reminds me of a planaria....

 

[MTBake]

No idea. Following along to see if anyone can id these.

 

[Killervector]

Agree. Looks exactly like a planaria!

 

[pdxmonkeyboy]

John, that is most definitely a planarian...aka flat worm. Likely procotyla based on its color. You should shift some gravel and scope it to give an idea of abundance. You might want to treat with dewormer.

 

[stacksoner]

What magnification was this microscopy observed at?

 

[SuncrestReef]

What magnification was this microscopy observed at?

It was captured at 40x, 80x, and 200x at various points throughout the video, using an Amscope microscope and recording the video on my iPhone attached to the eyepiece with this universal smartphone adapter:

 

[vetteguy53081]

Planaria are a variety of flatworm that are considered a pest by the majority of aquarists.
These flatworms can quickly multiply in number and, as you will soon learn, can be dangerous to other members of your aquarium.
There are actually two types of planaria flatworm commonly found in aquariums:

• white planaria (Procotyla)
• Black and brown planaria (Dugesia)

To make things more confusing, some types of planaria can change color according to what they eat. Colored flakes, for instance, can turn a planarian a lovely shade of pink. Besides the color, they are nearly identical in appearance. The best way to i.d. them is their crossed-eyes. This one does not have it and may be a rhabdocoela worm.