Engagement Party

I am planning an outdoor engagement party for my son & future daughter-in-law for about 35 people.
Looking for some themes and decorating ideas. My son loves fishing. What do you think about little fish bowl on the tables. Maybe with floating flowers or possibly golf fish.
Are there any engagement decorations available anywhere. I haven`t seen any in the party stores.
Please give me whatever help you can.
Thank you.
Cheryl