As far as feeding the Jaguar, have you tried feeding it fresh fish, beef heart, shrimp, live bloodworms, or crickets? These are all good foods for carnivores.
If you have to set up a feeder tank, set up a 50g as a normal tropical tank (heater, filter, cycle it normally), and get either a dozen guppies (9 females, 3 males) or a couple of convict cichlids, as Dino suggested. Feed them high-quality food, and do regular water changes. If they are malnourished, stressed, or subjected to high levels of nitrogen, the Jaguar will be, too.
Your response to Dino in "Who runs their own feeder tank" was unacceptably rude. Continued attitude like this will result in you being banned. Yes, Dino gave you more information than you asked for. It was information that you needed. Looking at your posts, it seems that the Jaguar was kind of an impulse purchase, and that you weren't ready to care for it when you got it.
In the future, if you feel a response like this was unwarranted, either deal with it in private with them, or calmly and kindly explain to them why you felt their response was unwarranted.
