what is this？ slug? flatworm?

[Mr Blue]

Hi guys! a friend of mine finds this thing breaking out in his tank, it has a white part in the middle, moves fast, has no tentacles, wandering on the glass or sand. what's this? is this thing harmful?

 

[stewy14]

c

a friend of mine finds this thing breaking out in his tank, it has a white part in the middle, moves fast, has no tentacles, wandering on the glass or sand. what's this? is this thing harmful?

an u make it a yt video plz

 

[Mr Blue]

c

an u make it a yt video plz

 

[stewy14]

im bumping for you
that thing looks cool

 

[Sophie"s mom]

Maybe @ISpeakForTheSeas can help ID this guy.

 

[kevgib67]

Maybe @ISpeakForTheSeas can help ID this guy.

I don’t think @ISpeakForTheSeas knows anything about identifying things but I guess it wouldn’t hurt. How’s the little pup Sophie?

 

[ISpeakForTheSeas]

Maybe @ISpeakForTheSeas can help ID this guy.

I don’t think @ISpeakForTheSeas knows anything about identifying things but I guess it wouldn’t hurt. How’s the little pup Sophie?

Haha, I definitely still learning - OP, it's hard to say for sure from the vids (blue light and pretty distant from the top of the critter), but I would guess a Runcina species headshield slug; so give a look and see if any seem like a match:

I'm thinking a Runcina sp. headshield slug - if so, members of the genus reportedly feed on diatoms, so it would be a keeper.

If you do a Google Images search for "Runcina species" you should get a number of good images you can compare with; the (at least mostly) solid white and black stripes forming the collar there can be found a few different species in the genus, but I'm not familiar enough with the genus yet to know which species your specimen might be.

I've been able to find for sure is that they reportedly eat diatoms, algae, and "dead marine phanerogams" (dead seagrass).

 

[Mr Blue]

thanks! great help! though i find no exact match on google, this really looks like some of the Runcina species, many similar traits they have. Now i can tell my friend to keep it in his tank

Haha, I definitely still learning - OP, it's hard to say for sure from the vids (blue light and pretty distant from the top of the critter), but I would guess a Runcina species headshield slug; so give a look and see if any seem like a match:

Haha, I definitely still learning - OP, it's hard to say for sure from the vids (blue light and pretty distant from the top of the critter), but I would guess a Runcina species headshield slug; so give a look and see if any seem like a match:

 

[Mr Blue]

im bumping for you
that thing looks cool

thanks! and thanks to ISpeakForTheSeas, we now know it might be one of the Runcina species headshield slug, total harmless

 

[Sophie"s mom]

I don’t think @ISpeakForTheSeas knows anything about identifying things but I guess it wouldn’t hurt. How’s the little pup Sophie?

Sophie is doing great! Thank you for asking. She is showing her age though. She is 12.

 

[stewy14]

Sophie is doing great! Thank you for asking. She is showing her age though. She is 12.

she doing butterfly shorts and Stanleys yet?
cuz my 10 y/o sis is, and its 40 degrees today

 

[Sophie"s mom]

she doing butterfly shorts and Stanleys yet?
cuz my 10 y/o sis is, and its 40 degrees today

Ha ha! My Sophie is a Boston Terrier dog! So no shorts, just a crazy little dog, even at 12 years old.