Hi,
these big applesnails are too big to swallow, and COULD be fine, but some channa like to bite into their tentakels.
The mentioned shrimp will work great, but they will easily go on frosted shrimp (for example Macrobrachium lancestri from Vietnam). Small snails are a welcome snack by nearly all of my channa.
My bleheri go crazy when I feed them sticks and flakes. So live food is not realy a must.
Cheers