Hello-Was my thinking too, but have not been able to get a sample.
24 hours into start of prazi treatment.
Have had no luck getting her to eat yet. I have tried earthworms, muscle shrimp, and frozen blood worms. Been feeding other Ray first then trying to target feed her with metal tweezers ( used to smash food with this method). Breathing still seems very fast and labored her activity seems less than yesterday.
Will keep trying with worms and usaul food
You are on the right track with the prazi treatment. I would say don't give up on prazi just yet. Sometimes I do not see the results until the start of the second treatment. For bad cases at least. As an example I recently took in a 20" henlei that is very skinny, sunken head and wouldn't eat either. She has finally started eating after about a week of efforts and prazi. The lights should be off, water warm and excessively oxygenated. For sure keep her separated from other animals.
Stick to earth worms if possible until she takes them. Blackworms can be a good alternative to younger/smaller rays. Sometimes throwing more food options at a stressed animal will result in no ingestion at all when smaller consistent amounts may have been successful. I got her eating via earthworms (triggers instinctual reaction to the electrical impulses from the worm and movement. Not until she had me sweating though.. Good luck man, keep us posted