 Hyperparameters optimization

# 🚀 Feature Request

Hyperparameter optimization for the fish environment of dm_control.
## Motivation
I tried easy,medium,hard sets for the upright and swim task of the fish environment but neither of them seemed to work for the swim task.

Could you provide the way(script) you found the hyperparameters for other envs? Otherwise I can open the pull request if I succeed for the fish env.
