Flat worms. Good or bad kind.

[Biglurr54]

I set up a small desk pico with some rock from my main display and sand from my display. The only thing I added was mangroves from algaebarn. The pico is not connected to the main display but I am planning on connecting it.

I found these worms on the glass and I'm wondering if they are flat worms and if they are bad. My main display is packed with SPS and I haven't seen these in the main display but with a copperband and a wrasse they may be kept in control in the display and that's why I havent seen them. Either way, they are all over the pico and I don't want to connect the pico if they are the bad ones.

 

[joseserrano]

they look like planaria, but I dont think there are any good flat worms.

 

[Justin Cook]

They do look quite a bit like planaria (large, red) but they could be the acoel flatworms. I've never had an issue with the acoel kind but have treated for the red planaria. 3 out of 4 my systems have them and they don't bother anything. I've got a wrasse or springeri damsel is each of my tanks and rarely do I see one. I've treated for them in the past but they just aren't much of an issue for me so I let them be with some natural predation. If you do want to treat for them, it's important to do it as early as possible while the numbers are still low. Problems arise when a large number of them all die at once.

Side note: I do sell from my frag system and would treat if they were in there since I don't want to pass along anything that isn't a problem for me but could be an issue in another system. Regardless, they don't attack corals outright; they just smother them if the numbers are high enough.