(ר' עקיבא אומר כשעת התביעה (בבא מציעא מ"ג

What case is ר' עקיבא talking about? Is ר' עקיבא talking about the same case as ב"ה and ב"ש, namely שבח?

Tosafos says it can't be. Tosafos asks, if ר' עקיבא holds that שינוי קונה then he was קונה the שבח and he should keep it, if he holds that שינוי אינו קונה then he should pay for what grows even after the תביעה. Therefore Tosafos says that ר' עקיבא is talking about where the price of the object goes up. ר' עקיבא holds that even though כל הגזלנים משלמים כשעת הגזילה a שולח יד is different and pays the value of the object כשעת התביעה even if it goes down which is a tremendous chiddush.

The בעל המאור learns that ר' עקיבא is also going on the same case as ב"ה and ב"ש (namely שבח). He explains that ר' עקיבא holds that he doesn't get the קניני גזילה to be קונה the שבח until the time of the תביעה and therefore that is the time that is קובע. In other words, any שבח until the time of the תביעה belongs to the נגזל. This answers Tosafos's objection, ר' עקיבא holds שינוי קונה but only from the time of תביעה because that is when he gets the קניני גזילה.

The Rif says the opposite of the בעל המאור. The Rif says that any שבח that the גזלן takes from the animal is his until the תביעה, after the תביעה the שבח belongs to the נגזל.