As the contents of this page no longer exist in Old School RuneScape, this article is preserved for historical purposes.
The Big fish is a random event. While fishing, a large fish would sometimes appear in a fishing spot and eat the player's fishing equipment, then spit it somewhere nearby, usually 3 to 10 squares away. When this happened, the player had to find their equipment quickly before someone else saw it and took it or it would disappear. When the player had found the equipment, then they could go back to fishing. When this event happened, the fishing spot would usually move to a new location as well.
The examine text for the big fish was 'I can see fishes swimming in the water' which was the examine text for a fishing spot. It is unknown if this was a glitch or not.