Endugu

Last time I saw one it was $2500 ca

I don't have an online source for you, but search Monogenetic or Monogenea flukes such as Gyrodactylus.

My biggest issue with fluval is the amount of water that bypasses the media and enters back into the tank. They are great for circulation, but not so good biologically.

It could be Ich or gill flukes. Consider raising the temperature about 5 degrees and treat with non-iodized salt (aquarium salt) for about a 4 weeks. If the behavior persists after such time then it is likely gill flukes and they should be treated with an appropriate medication. If you want my recommendation for the dosage of salt, let me know.

The ray is very nice, but wow, is that a Merodontotus tigrinus?