Good or bad Hitchhiker?

[A-Jay]

This is in my tank and no clue what it is I thought I saw it few days ago now it looks double in size

 

[Doctorgori]

Looks like a slug

 

[SAY]

looks like some type of nudibranch to me. Good or bad? depends on what it eats.

 

[ISpeakForTheSeas]

Yeah, that's a nudibranch, and one of the one's that feed on cnidarians (corals, anemones, hydroids, etc.) - what specific kind of cnidarian they feed on depends on the exact nudibranch species.

Have you seen any corals struggling in your tank? SPS and Softies are the typical prey item corals.

 

[A-Jay]

I have seen a couple that have started to be eaten yeah

 

[ISpeakForTheSeas]

I have seen a couple that have started to be eaten yeah

I would dip the corals if possible to see if any adult nudibranchs drop off (remove them if they do), and I would inspect them closely for egg spirals.