fish trapping?

Hi,

I have a boat in a marina. I don't want to take the time to fish,
but do have some interest in wildlife, including fish. It would be
cool to trap them just to see what comes up, and then let them
go, if it's fairly easy to build some type of fish trap that won't
hurt them. Can anyone suggest some good way(s) to trap fish
from a dock in water about 60 feet deep, and/or where to find
out more about it online?

Thanks,
David