I would love to be able to help your Dasyatids. Unfortunately, there's not a lot of information on stingray diseases out on the net. I would suggest that you look at the link below, and possibly post a message on there. It seems that that forum is all about stingrays, and the moderator there has plenty of experience keeping stingrays. I only have the knowledge from ichthyology class, and unfortunately we didn't learn about the diseases.

I will promote your post on this forum, and hopefully you can get a good answer between the two sites. I wish you the best of luck with your beautiful, unique pets. Please keep us updated.
Stingray FAQ

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Phishie

"An ounce of prevention is worth a pound of cure."