in my experience velvet is pretty rare. they only fish i have ever seen with velvet are angels. I'm not saying you don't have it. i don't know. but if you really think you do, then treat the tank for velvet.
if you're having a hard time getting the jacks to eat i would toss some isis shrimp in there. I've never seen a fish turn down miss shrimp.
if you're having a hard time getting the jacks to eat i would toss some isis shrimp in there. I've never seen a fish turn down miss shrimp.