This how I test those new foods and plants before introduce to the tank.

Tesco Cheras , think all other Tesco should have, if not go find any JustLife organic shop, there is one in MidValley opposite Cold Storage.
To prepare , clean them, boil the the leaf with some stem for 1~2min. Let it cool down in a plastic bowl for 15min, then put them in
the fridge for 24 hours, The leaf will able to sink after this.
Give them everyday one leaf or more(if you have many shrimps >200++).

where do u get your shrimp supply? Nowdays no stock of shrimps everywhere.

they will eat dwarf shrimps... cherry , blue jelly .. all they eat esp the berried one.
If your shrimps mysteriously disappear, their are the main suspect. Trust i saw their cruel acts against shrimpskind.