I agree with conch about the non-fish related stuff, sometimes its good to do stuff like that just to socialise a bit more.
But as for the meeting, my general thoughts would be to keep the official [boring] stuff to a bare minimum and cut to the chase with an interesting guest speaker, slideshow, whatever. I'm bordering on leaving another [not-fish-related] society because of its long drawn-out meetings, run by a bunch of old retired people who still like to pretend they are important. The first half of the meeting consists of the president and the secretary droning on about nothing in particular, then there's a way-too-long interval/cup-o-tea period for all the oldies to socialise, then finally you get to hear the speaker. Keep the meetings short, punchy and to-the-point and you'll be right.
BTW, do people actually catch their fish and bring them along to the meetings in a bag/jar/bucket to show everyone?!?!!!