Scutariella japonica: The 'Nose Worm' on Dwarf Shrimp
Scutariella japonica is a tiny white flatworm that lives on the head and gills of Neocaridina and Caridina shrimp. Learn how to recognise it, why it is mostly a commensal, and the salt-dip approach used to remove it — without ever using copper.
What it is
Scutariella japonica is a temnocephalid flatworm (family Temnocephalidae) that lives as an ectosymbiont on dwarf shrimp such as Neocaridina davidi. It reaches roughly 2.6 to 3.1 mm and is usually seen as tiny whitish worms standing up on the shrimp's rostrum (nose), which is why it is nicknamed the 'nose worm'. Its main microhabitat is actually the branchial (gill) chamber, where it also lays transparent-white eggs.
Is it harmful?
Scutariella feeds on rotifers and protozoans — microfauna, not shrimp tissue — so it is largely a commensal. However, heavy epibiont loads may adversely affect the host, and their presence often signals suboptimal water quality. Distinguish it from co-occurring epibionts: the annelid worm Holtodrilus truncatus and the green alga Cladogonium kumaki.
Salt-dip treatment
The Shrimp Farm describes an individual salt dip: dissolve aquarium or pickling salt into a cup of tank water (a smaller dose for sensitive Caridina than for hardier Neocaridina), dip each shrimp briefly, then move it to clean tank water, repeating over several days until symptoms clear. UF/IFAS salt-therapy guidance independently supports short salt dips as an anti-parasite tool.
- Prepare a dip of aquarium or non-iodized salt in a cup of tank water, using a lower dose for delicate Caridina.
- Dip each shrimp for about a minute, watching it closely.
- Move the shrimp to a clean container of fresh tank water.
- Repeat daily for several days until the worms and eggs are gone.
- Fix the underlying water quality so that they do not return.
Sources: pmc.ncbi.nlm.nih.gov ; www.theshrimpfarm.com ; ask.ifas.ufl.edu (UF/IFAS VM007)