Cut-up parts of fish probably deserves a special category. Any kind of fish can be used and is a natural food for many species of game fish. You can adjust the size of the bait easily, and it is inexpensive because you can catch your own or cut a lot of pieces of bait from one bigger bought fish.
Kinds of Dead-Fish Baits
Any kind of bloody or oily fish makes good cut bait for catfish, stripers, and most saltwater fish. Bigger baitfish can be cut into smaller parts for smaller fish or to make it bait more hooks. You can also cut large fish into chunks to make it the right size for the fish you want to catch and also to make it go further. One reason cut bait works so well is it releases the scent of the fish into the water better.
Keep a sharp knife and cutting board with your fishing tackle and make cut bait anytime you want to use it. You can chop up a fish you catch or cut up one you brought along. A bigger fish is easier to handle and carry if you keep it whole until you need to cut it up later.
How to Fish Dead-Fish Bait
A mullet can be purchased cheaply in most grocery stores and cut into quarter-size pieces for catfish bait. Those pieces make good bait for still-fishing with rod and reel and also for baiting trotline and other set hooks. A six-inch gizzard shad or blueback herring can be cut in half and each half used to catch stripers, hybrid, and catfish. Troll with the tail section or fish it on the bottom on a fish finder rig for both species.
Chop menhaden in half for a bite-size bait for smaller saltwater cats, grouper, and other bottom-feeding fish. For big fish like sharks you might need to cut a ten-pound fish in half and use each half for bait. Cutting it releases blood and oil into the water to attract the sharks. Suspend big baits under a big cork or even use a balloon to keep it at the right depth for the fish you're after.
It's easy to cut fish into pieces on the spot for whatever purpose you need at the moment. Cut a long thin strip for more action and less drag in moving water. Cut a chunk with several skin tails for even more action. A cube might work best for bottom-fishing while a long teardrop shape will cast and retrieve better. Experiment with different shapes and sizes to see what works best.