Denison is native of southern India, and this is why it’s so cheap there. They are on the endangered species list there because of over harvesting.Here in India, Denisons are around $1 each for 2.5" to 3" sizes...
definitely dont want them as feeders...
Get to Know the Denison Barb Fish Species
Also called Miss Kerala, the denison barb is a handsome but endangered fish. Learn more about the habitat, care, feeding, and breeding of this barb.
www.thesprucepets.com
Price in northeast US is still not cheap, $12 for 1 inch fish in Petsmart. Glad to hear that they are now tank bred, and if so, price should come down soon.
As for training predactor to become non predator, I witnessed it in many of my predatory cichlid. Mine lost the instinct of hunting down live fish if they don’t jerk around like prey. I have never kept arrow, so do not know if they can be tamed like cichlid, but I have observed it in public aquarium as shown in the video in Post #4 where hundreds of cardinal Tetra and other mouth-size fish coexist with a 24” arrow.