Fishbone refers to a type of bone found in fish. It is a thin and slender bone with many tiny branches resembling the shape of a fish's backbone. Full definition
''... a shriek remains nailed in the dark corridor like a big fishbone in the throat of an unknown guest...» Yannis Ritsos, The Dead House (stateofconcept.org)
Together they have developed a legal expert system shell called eGanges that relies not on decision tree logic but rather on something called river logic, a refined Ishikawa fishbone. (slaw.ca)
You may find it helpful to create a cause and effect diagram (e.g. fishbone diagram) to explore the root cause of the problem. (tribaleval.org)