In general, we use the following command to generate a fixture for one app:

python manage.py dumpdata appname --indent=4 --output=<path-to-your-output-file>

For example, to generate a fixture for the tendenci stories app:

python manage.py dumpdata stories --indent=4 --output=stories.json

To generate only for a specific model Rotator, for instance:

python manage.py dumpdata stories.rotator --indent=4 --output=stories_rotator.json

For more details on dumpdata and fixtures, please refer to Django's official documentaion. 

https://docs.djangoproject.com/en/1.8/ref/django-admin/#dumpdata-app-label-app-label-app-label-model

https://docs.djangoproject.com/en/1.8/howto/initial-data/