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Ishikawa diagrams are used to represent causes of a specific event or problem. They are also known as fishbone diagrams, herringbone diagrams, or cause-and-effect diagrams. The diagram resembles a fish skeleton, with the main problem at the head and the causes branching off from the spine.
This is a new diagram type in Mermaid. Its syntax may evolve in future versions. Use the ishikawa-beta keyword.

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Basic Ishikawa diagram

This example analyzes the causes of a blurry photo:

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Syntax overview

The structure of an Ishikawa diagram is created using indentation:
  1. First line: The event or problem being analyzed
  2. Subsequent lines: Causes of the event
  3. Indentation: Creates the hierarchical “fishbone” structure

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Problem statement

The first line defines the main problem or effect: 
ishikawa-beta
    Blurry Photo

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Primary causes

Main categories of causes are defined at the first level of indentation: 
ishikawa-beta
    Blurry Photo
    Process
    User
    Equipment
    Environment

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Secondary causes

Sub-causes are defined by further indentation: 
ishikawa-beta
    Blurry Photo
    Process
        Out of focus
        Shutter speed too slow
    User
        Shaky hands

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Nested categories

You can create sub-categories using uppercase text and additional indentation:

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Common use cases

Ishikawa diagrams are widely used for:
  • Quality management: Identifying root causes of defects or quality issues
  • Process improvement: Analyzing factors affecting process performance
  • Problem-solving: Breaking down complex problems into manageable components
  • Risk analysis: Identifying potential causes of failures or incidents
  • Brainstorming: Organizing team discussions about problem causes

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Example: Website downtime

Here’s an example analyzing causes of website downtime:

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Example: Customer complaints

Analyzing causes of customer complaints:
Use uppercase text for sub-category headers to create a clear visual hierarchy in your fishbone diagram.
The fishbone structure is automatically created based on your indentation. Make sure to use consistent spacing (tabs or spaces) throughout your diagram.

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