I filled mine with a hose, let the temp adjust a couple days. Worked fine, as my fish were already used to the local tap water. It refills with rain and water from the sprinklers, otherwise hose water works again.
Smaller fish I figure can feed themselves, but a few times a week I do supplementary feed them. Fish always look fat, so I assume they're getting their fill somehow.
Shrimp, somehow ended up with them in the tub a few times. As long as there's hiding spots Neos do fine. Actually seems to bring out really fantastic colors in them, blows away everything else I've ever produced. Culling is pretty much impossible unless you drain the pond though