James, these are some suggestions based on what I've seen my fish supplier do:

1) Oxygen is better than air.

2) Water temps are important; I've seen my fish guy use bags of ice, and also, water frozen in plastic jugs-then just put a few frozen jugs in.

3) I have seen him use a little salt many times. I believe it is regular salt, however, I don't know the proper mix. Pros will be able to clarify.

Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."