Sand used for bottom dwellers should be without sharp edges.
For fish that live mostly in the mid and upper regions of the tank, any clean sand will do.
As for the packaged sand sold for aquarium use, avoid the unnatural colors, as the dyes used on the sand are probably not that good for the fish.
It may not be a good idea to use too fine a sand with an undergravel filter. In my experience it doesn't allow for good filtration for the bacteria in the substrate, and it can also be sucked up in the uplift tubes, keeping your tank cloudy. However, it should be fine if you have an outside filter. Remember, if you have loaches, they'll rapidly disappear, burrowing into fine sand. Cichlids and goldfish will root relentlessly through it also. OK, thanks for letting me ramble! Guppygranny
As long as it's 'fish-safe' it doesn't really matter. Very few things are pure white in nature. White could make some species appear blanched or pale as they could adjust their coloring to the white bottom of the tank. What other decorations are you planning? Guppygranny
Sand isn't recommended for the exact reasons grannyguppy stated but with a HOB or canister it is great. Just make sure your uptake tube isn't down close to the sand. I have three sand tanks and really like them.
The dojos will bury in the sand, but my yoyos and clowns don't. The kuhlis are always sticking their noses down in it looking for food and the hillstreams scoot over the top like little space ships checking for any goodies they can find