A child’s [toy] wagon is susceptible to midras-contamination, and it may be moved on Sabbath, but it may not be dragged [over the ground] except over cloth. R’ Yehudah says: No utensil may be dragged [over the ground] except the wagon, because it [only] presses.

We may not catch fish from a fish pond on Yom Tov, nor may we place food before them, but we may catch animals or fowl from enclosures, and we may put food before them. Rabban Shimon ben Gamliel says: Not all enclosures are the same. This is the general rule: Whatever requires trapping is prohibited, and whatever does not require trapping is permitted.