I don't keep rays and thus, have no experience with their sensitivity to medicines.
The photo of the worms does not allow identification, but planaria are relatively common in tanks, and a likely culprit. Planaria are NON-PARASITIC, and are harmless to the fish, although unsightly and indicative of other potential issues. Usually they disappear on their own after fixing the problem. Perhaps overfeeding? Or perhaps they were simply introduced recently with decorations or something else. If they were accidentally introduced and overfeeding is not taking place, they should dwindle on their own. Also, they hate salt, even at low concentration.
I know you already ordered the medicine. It may be effective - I don't know it.
However, in their own description it states: "Also kills Planaria and non-parasitic nematode worms"
Planaria are Platyhelminthes (flatworms), NOT Nematoda (= Nematelminthes, or roundworms). Just the improper wording of their advertisement regarding the taxonomy of the creatures it supposedly acts on, makes me trust it somewhat less, even if effective.
The photo of the worms does not allow identification, but planaria are relatively common in tanks, and a likely culprit. Planaria are NON-PARASITIC, and are harmless to the fish, although unsightly and indicative of other potential issues. Usually they disappear on their own after fixing the problem. Perhaps overfeeding? Or perhaps they were simply introduced recently with decorations or something else. If they were accidentally introduced and overfeeding is not taking place, they should dwindle on their own. Also, they hate salt, even at low concentration.
I know you already ordered the medicine. It may be effective - I don't know it.
However, in their own description it states: "Also kills Planaria and non-parasitic nematode worms"
Planaria are Platyhelminthes (flatworms), NOT Nematoda (= Nematelminthes, or roundworms). Just the improper wording of their advertisement regarding the taxonomy of the creatures it supposedly acts on, makes me trust it somewhat less, even if effective.