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Related FAQs; Flatworms/Planaria 1, Flatworms 2Flatworms 3, & FAQs on: Flatworm Identification, Flatworm ID 2, Flatworm ID 3, Flatworm Behavior, Flatworm Compatibility, Flatworm Control, Predator Control, Chemical Control, Flatworm Selection, Flatworm Systems, Flatworm Feeding, Flatworm Disease, Flatworm Reproduction,

Related Articles: Pest Flatworm Control by Anthony Calfo, Worm Diversity

/The Conscientious Reef Aquarist:

Flatworms, including "Planaria" & Marine Aquariums, Part 3

To: Part 1, Part 2,


By Bob Fenner


Genus Thysanozoon:

Thysanozoon flavomaculatum Red Sea image.

Thysanozoon nigropapillosum (Hyman 1969). Dorsal surface black with short papillae tipped with yellow. White band around edge. Mid Indian Ocean east to Western Pacific. Photo taken off Pulau Redang, Malaysia. 

Thysanozoon-Acanthozoon sp. Raja Ampat image.

A Host of Unknowns:

An undescribed Euryleptid in Bali 2014. Indo-West Pacific. To 3 cm, 1.25"

Bigger PIX:
The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.

Bigger PIX:
The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.

Parasitic Flatworms: Black-Spot Disease of Yellow Tangs

My graduate school roommate Mike Kent worked out the life-cycle of this Platyhelminth, Paravortex for his Master's Thesis. Other authors list the use of organo-phosphate containing medications to rid Yellow Tangs and other fishes (7 families, 130 some species) and their system of this turbellarian, but a simple freshwater dip, sans copper or anything else, wipes them out without having to put anything in your main system. After this knowledge became common and a routine freshwater dip procedure was adopted by wholesalers, we had a Dickens of a time getting more Paravortex. If your system will accommodate a cleaner goby, shrimp, by all means include one.

Flatworms as Predators!

Bigger PIX:
The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.

Flatworm Predators on Parade! 

Due to their bad taste, often outright toxicity, most flatworms are unpalatable to predators. However, there are notable exceptions. Some that may work are listed/pictured below:

Chelidonura varians Eliot 1903, THE Flatworm Eating Sea Slug! Tropical Indo-West Pacific. To seven cm. in length. This one off of Heron Island, Queensland, Australia. 

Lysmata wurdemanni (Gibbes 1850), Peppermint Shrimp, Caribbean Cleaner Shrimp. Tropical West Atlantic. Lives singly or in groups. Gets along with all aquarium species. Commercially produced. A reclusive, sometimes misidentified species (there are other shrimp from the area that are similar) used in the fight to limit Aiptasia Anemones in aquariums.

Halichoeres chrysus Randall 1981 (1), is a fish of two "good" and one bad common name. It should be called the Golden or Canary Wrasse for its bright bold sun-yellow color, but is most often listed as the Yellow Coris Wrasse (Arggghhh!, it is not a Coris genus member of course). This is an exemplary aquarium species that is suitable for peaceful fish-only and reef systems. To a mere 4 inches or so total length. Aquarium & S. Sulawesi photos. Eastern Indian Ocean distribution. http://fishbase.sinica.edu.tw/Summary/speciesSummary.php?ID=4855&genusname=Halichoeres&speciesname=chrysus

Pseudocheilinus evanidus Jordan & Evermann 1903, the Pin-Striped or Striated Wrasse (2). I like this fish's other common names, the Disappearing or Vanishing Wrasse for its bashfulness. To a grand size of three inches. Indo-Pacific, including Red Sea and Hawai'i. Two in the Red Sea.

Pseudocheilinus hexataenia (Bleeker 1857), the Sixline Wrasse (2). A feisty, though small (to 4") a reef tank species. Indo-Pacific, including the Red Sea in its distribution. Aquarium and Queensland, Australia images.



    All Polyclad Flatworms are carnivorous, and specific about their prey. Most feed on sea squirts, bryozoans, small worms, crustaceans, or snails, but some are cannibalistic.


    Platyhelminths are true hermaphrodites... being both male and female. Cross-fertilization is the rule with a "pair" rudely stabbing one another with a hard penile stylet to enact sperm transfer. As you know due to exposure with Planaria, they can also generate new individuals by splitting asexually.

To: Part 1, Part 2,

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