Dog biscuits are one of the top baits for carp, but when hard they're tough to put on a hook. In addition, dry dog biscuits can expand in a fish's stomach and cause health issues. The solution is to soften and expand the dog biscuits before you use them as bait. They're much easier to hook when soft, and they won't harm the fish.
Place the dog biscuits in a sealable plastic bag. The dog biscuits will expand as they soften, so fill the bag only to one-third or one-half full.
Add enough water to the bag to cover the dog biscuits.
Seal the bag and leave it for approximately an hour.
Check on the bag to see if the dog biscuits have soaked up all the water. If there is no water left in the bag, add more.
Pour out the excess water once the biscuits have fully expanded.
Store the bag in the refrigerator until you are ready to use the soaked biscuits. They will keep for several days.
When you're ready to use the dog biscuits, take them out of the bag and let them dry out a little in the sun. The biscuits will develop a tough skin that will make them easier to keep on the hook.