When heavy rod fishing, you should bring your rod, your knife, and 25 fishing bait or feathers, go to the fishing spots and catch a full inventory of fish and cut them into fish offcuts and caviar/roe. If your inventory gets full of offcuts and roe/caviar, drop the fish offcuts and continue fishing/cutting using the caviar/roe. You can pick up the offcuts after you have used up the caviar/roe as they are also bait. Dropping the caviar/roe takes more time to drop than the stackable offcuts. This nets you around 50 to 60k an hour at 70 fishing. Note that it is possible to run out of bait just from cutting open the fish so bring some back up bait/feathers to be on the safe side.