Cearbhaill,
Although I can appreciate your intent in iniating lively debate, I wasn't in fact commenting on your post directly. I believe I did so previously. I was responding to jb_lyndon's post, as I should have made more clear.
In regards to your post, I believe I mentioned that there should be guidelines and there should be consequences, and that that was entirely the perogative of the parent involved. How they involve their children in their aquaria hobby is up to them, and how they reprimand for interfering in the same is also up to them.
In regards to jb_lyndon's post, I believe I was fairly clear on that as well.
Instilling respect of other's belongings as well as their own should be a component of parenting. Agreed. However, you cannot expect (as jb_lyndon would) to have a conversation with a 3 year old about the cycling process, the effects of introducing foreign items into that process, the amount of work required to set up a 150, how their actions stalled the process, wasting 150 g of water, etc. etc. at length, as jb_lyndon suggested. That's ridiculous. Regardless of how precocious a child might be intellectually, he or she is still only a child.
I don't believe matt was complaining in the original post, nor do I think that he was inviting comment on his parenting skills or soliciting advice about raising his children. Plenty of people responded to his post without make sarcastic comments referring to his children as "precious," or "little angels" (a la jb_lyndon) or to quote your post, "little darlins'," or going to pains to point out how a 5 year old and a 3 year old "trashed" his tank. They threw some stuff into an unstocked tank. (Incidentally, the concern should be for safety of the children, not safety of the tank. They didn't take sledgehammers to the thing after all, although there is a real possibility that they might have fallen in.) Matt called no harm, no foul, I assume he took appropriate action with his children (his appropriate action, not ours), and moved on. He's not the one responding to this, I am. And I still don't think it's anyone's place to tell the man how to discipline his children, particularly not in the manner in which jb_lyndon did.
But that has nothing to do with fish, so let's move on, shall we?
eta - yes I can spell correctly...sometimes