pacific sardine tank

Wow! This must be a sight to behold? Do they just swim round and round the donut all day or do they jazz it up with a change in direction or zig-zagging
This reminds me a bit of the reef area in Leipzig with a similar mural with the different sharks and their sizes and with a reef tank instead of sardines but the same shape and overall feel.

Not sure if they change direction or not. That's a good question.

I wonder what they get out of going round and round the tank. I wonder how dizzy they are by the end