those in newspaper are call sarong in malay in english i dont know maybe rag worm or wat and other kind that selling in a container with saw dust are call sand worm or blood worm cos when you hook through it lots of blood comes out.
from wat i know most fish like to eat sarong btu if you are trying to keep sarong the fish must be bigger or swim fast cos sarong have two sharp teeth those that usually use it for fishing should know as for where to get it weekend there are a lot along beach road and changi village weekdays only some of the tackle shop bring in