They arent used as a staple, but a filler with the massivor, they get fresh food in the evenings,
I will atest to the work NEA did on fatty liver as I used their info in some of the work I've done with captive FW ray husbandry protocols used in many US aquarium facilities.
FLD is an ongoing problem in captive elasmobranch species (not just FW rays). One of MANY topics I wish we shared more openly about from the Symposium a couple years ago at Shedd.
why can't I figure out what NLS is or where to find it?
I also find NLS - particularly when purchased in buckets (which most ray keepers would) is quite dusty.