Minecraft wiki entry for String, associated text: String has a 0.6% (3⁄500) chance of being caught when fishing with an unenchanted fishing rod. The chance decreases to 0.5% (1⁄200), 0.4% (1⁄250), and 0.3% (3⁄1000) if the fishing rod is enchanted with Luck of the Sea at enchantment levels I, II, and III, respectively.