--- description: '"Improve YOLO model performance with on_fit_epoch_end callback. Learn to integrate with Ray Tune for hyperparameter tuning. Ultralytics YOLO docs."' keywords: on_fit_epoch_end, Ultralytics YOLO, callback function, training, model tuning --- # on_fit_epoch_end --- :::ultralytics.yolo.utils.callbacks.raytune.on_fit_epoch_end