In beitza (3:1):
אֵין צָדִין דָּגִים מִן הַבֵּיבָרִין בְּיוֹם טוֹב, וְאֵין נוֹתְנִין לִפְנֵיהֶם מְזוֹנוֹת. אֲבָל צָדִין חַיָּה וָעוֹף מִן הַבֵּיבָרִין, וְנוֹתְנִין לִפְנֵיהֶם מְזוֹנוֹת. רַבָּן שִׁמְעוֹן בֶּן גַּמְלִיאֵל אוֹמֵר, לֹא כָל הַבֵּיבָרִין שָׁוִין. זֶה הַכְּלָל, כָּל הַמְחֻסָּר צִידָה אָסוּר, וְשֶׁאֵינוֹ מְחֻסָּר צִידָה מֻתָּר:
One may not catch fish from a fishpond on Yom Tov nor give them food, But one may catch game or fowl from animal enclosures and one may put food before them. Rabban Shimon ben Gamaliel says: not all enclosures are alike. This is the general rule: anything that still needs to be trapped is forbidden but anything that need not be trapped is permitted.
What does Rabban Shimon Ben Gamaliel mean?
1) Is he differentiating between fishponds (that we are prohibited from fishing) and animal enclosures (which we may hunt), and then bring the general rule to show the difference between fish and fowl, and he agrees with tana Kama, and both agree with the general rule?
2) He says that we are allowed to fish from some fishponds, but not others, and/ or we are allowed to hunt from some game and fowl enclosures, but not all. And then Rabban Shimon Ben Gamliel finishes his view, and the tana Kama brings the general rule, to show the difference between fish and fowl. And Rabban shim’on Ben Gamliel is arguing on the tana Kama, and the tana kama brings the general rule?
Or (related but slightly different):
3) He says that we are allowed to fish from some fishponds, but not others, and/ or we are allowed to hunt from some game and fowl enclosures, but not all. And then Rabban Shimon Ben Gamaliel brings the general rule to show which enclosures one is permitted to hunt from, and which one is prohibited to hunt from. And he argues with the Tana Kama, and brings the general rule?
Kehati brings a view that seems like it makes sense with the second or third possibilities, but he starts it with “Yeish Omrim”, which seems to imply that others go by the first possibility.