How to Catch and Cook Fish of Thieves Fish
Getting the Fish
Every catchable fish in the mod has a matching Spawn Egg and a Bucket form. The fish you can catch, cook, and bucket are: Ancientscale, Battlegill, Devilfish, Islehopper, Plentifin, Pondie, Splashtail, Stormfish, Wildsplash, and Wrecker. Each has a Spawn Egg (for example Ancientscale Spawn Egg, Battlegill Spawn Egg) and a Bucket of that fish (Bucket of Ancientscale, Bucket of Battlegill, and so on). Use the Spawn Eggs to place fish into water, or use the Buckets to carry a live fish and release it where you want.
Cooking Your Catch
Every raw fish has a cooked counterpart. The cooked items are: Cooked Ancientscale, Cooked Battlegill, Cooked Devilfish, Cooked Islehopper, Cooked Plentifin, Cooked Pondie, Cooked Splashtail, Cooked Stormfish, Cooked Wildsplash, and Cooked Wrecker. You can process each raw fish three ways: smelting, campfire cooking, and smoking. Put the raw fish in a Furnace to smelt it, hold it over a Campfire to cook it, or use a Smoker for the fastest result. All three routes produce the matching Cooked item.
Bait and Bones
Earthworms and Grubs are the worm-type items in the mod, useful when you are fishing for the catches above. Fish Bone is a separate item you obtain from fish and can use as a material. Keep a stack of Earthworms or Grubs on hand while fishing, and save Fish Bones for later crafting.