In the wild they are piscivores, so I feed mainly whole fish. Frozen silversides, live cichlids, live crayfish, king worms, earth worms, frozen krill, and pellets. They are not picky, but I've heard that some juvies will get addicted to blood worms and refuse other foods, so I avoid feeding blood worms. Be aware that juvies will cannibalize eachother. I highly recommend keeping a constant food source in the tank; baby cichlids, guppies, etc. They grow very fast and are always hungry. Cannibalism seems to stop around 5" in my experience.
8x4x4 would be a great tank size for a pack.
Juvies are very jumpy and great escape artists like most channa. Once they hit the 6" mark, mine were less jumpy. They currently range from 11-15" and pretty much never jump. The biggest threat for juvies in the aquarium are jumping and other pleuros.
I've never kept them in hard water, so I can't really say, although I have heard the same thing regarding color. My water here is pretty soft and my ph is around 6.7. One thing that I will say about color is that krill is supposed to promote blues and I gut load king worms with carrots to promote oranges. I've also heard that the blue pleuros are male and the more green pleuros are female. I haven't confirmed this though.
I don't mind answering questions; I'm happy to help if I can.
Thanks, Follen. While they were growing out in my wolffish tank, the wolf would school with them; an honorary member haha. If there wasn't such a difference at adult size, I would have kept them together.
Thanks for replying! So eventually I have to deal with their nasty habits of eating each other, so a constant supply of convicts will do. Btw, I've confirmed and read that algae based food promotes blue coloration, spirulina/algae based foods can be gutloaded to your feeders and might have that majestic blue pumped more.

In the Philippines we don't have any live bloodworms... No one has even considered getting some. We can't just add more mosquitoes in our ecosystem, mosquitoes are nasty killers here so no explanation can be justified to import some in here.