I'm not sure about Bettafish.com but at TropicalFishKeeping, at the bottom of the page there is something that says FORUM LEADERS. It gives a list of all the members of the moderating staff. Admin is on there and you can pm him from there.
To subscribe to a thread without posting you click the "Thread Tools" button at the top of each thread and then click "Subscribe to this thread". Similarly if you are subscribed to a thread and wish to no longer receive notifications you can go to the same place and click "Unsubscribe from this thread"