I think it’s a problem with the code rather with the headset.
You have two coding tabs and you define the “on activate” event listeners in the second one. This means that these event listeners will be applied after the whole code in the first tab has been finished. You should try to set event listeners like “on activate” always at the very beginning of your code to avoid this problem.
To make it work you can move the code from your first coding tab to the second and then delete it. Then you should have one single coding tab with your code like this:
To make all fish swim at the same time you can use the “execute in parallel” block. Then everything should work like intended.