we are planning to have a wireless livestream. Is it possible?
If the fish is VERY close to the surface, and the Arduino has nothing to do with the video data, yes.If the fish is more than a few centimeters below the surface, no. If the Arduino is expected to do anything with the video data, no.
Is there any way to save data from the camera using arduino?
Of course there are ways. The first thing you need to define is WHERE you want to store the data. The Arduino only has 2000 bytes of SRAM, so "in memory" is NOT where you are going to store the data.