Pest id

jayq16

Community Member
View Badges
Joined
Sep 23, 2014
Messages
54
Reaction score
35
Location
United States
Rating - 0%
0   0   0
I have these guys in my rocks near monti plates. All acros doing ok but my monti plates are not great so looked more closely, they look like a type of flatworm?


20260617_142315_15B208B2-92D7-42B5-9F01-B3378B5D3E28.png


20260617_142315_33C8B541-6FC9-46ED-9D05-ECBBC224FECE.png
 

EnterName

Valuable Member
View Badges
Joined
Sep 21, 2025
Messages
1,094
Reaction score
2,421
Location
Germany
Rating - 0%
0   0   0
Really hard to see... if you can't get better images, maybe you can describe how they behave/move? Are they fast? Are they slow? Do they move at all? Do they crawl along the container or do they actually swim through the water?

If you fear they are attacking your montipora plates you might want to check if you can see them actually sitting on or under the plates, where they could potentially cause harm. Maybe you will see more once the lights go dim/out. You could wait 1 hour past lights out and then check with a flashlight if there are more and if they start crawling onto your montis.
 
OP
OP
J

jayq16

Community Member
View Badges
Joined
Sep 23, 2014
Messages
54
Reaction score
35
Location
United States
Rating - 0%
0   0   0
Really hard to see... if you can't get better images, maybe you can describe how they behave/move? Are they fast? Are they slow? Do they move at all? Do they crawl along the container or do they actually swim through the water?

If you fear they are attacking your montipora plates you might want to check if you can see them actually sitting on or under the plates, where they could potentially cause harm. Maybe you will see more once the lights go dim/out. You could wait 1 hour past lights out and then check with a flashlight if there are more and if they start crawling onto your montis.
Thanks. I’ll catch more and see if I can get a better pic. They are small so difficult. They scoot along the surface like I’d assume a flatworm would. Maybe a type of planaria?
 

EnterName

Valuable Member
View Badges
Joined
Sep 21, 2025
Messages
1,094
Reaction score
2,421
Location
Germany
Rating - 0%
0   0   0
I assume Convolutriloba retrogemma (Red Menace / Acoel Flatworm)...? Looks definitely like some bad guys you don't want in your tank, even if my identification isn't fully correct 😟
 
Last edited:
OP
OP
J

jayq16

Community Member
View Badges
Joined
Sep 23, 2014
Messages
54
Reaction score
35
Location
United States
Rating - 0%
0   0   0
I assume Convolutriloba retrogemma (Red Menace / Acoel Flatworm)...? Looks definitely like some bad guys you don't want in your tank, even if my identification isn't fully correct 😟
Thanks and similar answer to Google image search, likely them. They aren’t in plague proportions yet so I can keep a way on them as well as siphon out here and there. I do have some mandarins that may be eating them, not sure. I’d do a six line wrasse but I think that will not make the mandarins happy long term :/
 

EnterName

Valuable Member
View Badges
Joined
Sep 21, 2025
Messages
1,094
Reaction score
2,421
Location
Germany
Rating - 0%
0   0   0
I assume Convolutriloba retrogemma (Red Menace / Acoel Flatworm)...? Looks definitely like some bad guys you don't want in your tank, even if my identification isn't fully correct 😟
Thanks and similar answer to Google image search, likely them. They aren’t in plague proportions yet so I can keep a way on them as well as siphon out here and there. I do have some mandarins that may be eating them, not sure. I’d do a six line wrasse but I think that will not make the mandarins happy long term :/
Those things can explode in numbers and hide really well... I would look for actual treatment options and I doubt you will be able to remove all by hand.

Chemical treatments like Salifert's Flatworm eXit apparently work great, but dying flatworms may release toxins so you want to treat them before they reach large numbers and become an issue. Others might have more experience with treatment methods, as I (fortunately) only had harmless ghost flatworms in my tank.
 

Privateye

Well-Known Member
View Badges
Joined
Jan 17, 2020
Messages
538
Reaction score
489
Rating - 0%
0   0   0
Definitely flatworms, and they look like the ones I've dealt with before. Flatworm Exit works very well - it will knock the population back significantly with one treatment. However, it never seems to get all of them. If that's all you can do, then you will have to treat again in the future.

A spotted mandarin and a sixline wrasse fixed it long-term.
 

ISpeakForTheSeas

7500 Club Member
View Badges
Joined
Nov 22, 2021
Messages
9,425
Reaction score
10,846
Location
United States
Rating - 0%
0   0   0
I assume Convolutriloba retrogemma (Red Menace / Acoel Flatworm)...? Looks definitely like some bad guys you don't want in your tank, even if my identification isn't fully correct 😟
Yeah, definitely in the Convolutriloba genus with that tail-end; I don't know how to tell the four species apart at this point, but not a keeper regardless.
 
OP
OP
J

jayq16

Community Member
View Badges
Joined
Sep 23, 2014
Messages
54
Reaction score
35
Location
United States
Rating - 0%
0   0   0
Bummer :/ ya seems like planaria. I’d like to avoid chemicals so may try a wrasse first and see if it reduces them some. I suppose I could hit it with FW exit while population is low but nervous on the impact to other beneficial creatures.
 
OP
OP
J

jayq16

Community Member
View Badges
Joined
Sep 23, 2014
Messages
54
Reaction score
35
Location
United States
Rating - 0%
0   0   0
Bummer :/ ya seems like planaria. I’d like to avoid chemicals so may try a wrasse first and see if it reduces them some. I suppose I could hit it with FW exit while population is low but nervous on the impact to other beneficial creatures.
Oh ya I have a lot of these now that I know what I’m looking for. I may have to go FW exit but nervous on it with the toxins.
 

TOP 10 Trending Threads

DO YOU THINK TECHNOLOGICAL ADVANCEMENTS ARE MORE HELPFUL OR HURTFUL TO REEFING?

  • More helpful.

    Votes: 10 37.0%
  • More hurtful.

    Votes: 2 7.4%
  • I think it depends mostly on the technology.

    Votes: 11 40.7%
  • I think it dependsmostly on the reefer behind the technology.

    Votes: 8 29.6%
Back
Top
Home
Post thread…
Market
What's new