They should be fine with the goldies; another member mentioned keeping one with her godlfish without any problems. Mystery snails (
Pomacea bridgesii) need about 2.5 gallons of water per snail, partly because of bioload and partly because these snails move around quickly and like to wander; though they poo a lot, they are worth it for the cleanup.
Mystery snails eat leftover fish food of all types. They LOVE zucchini slices and algae wafers.
Very soft, acidic water will deteriorate a snail's shell; hard water/high
pH makes ideal water conditions for sails. They need
calcium to keep their shells strong. They can ingest some calcium through calcium rich veggies (like zucchini), but they need more than that. The easiest way is to rinse the gunk off of eggs shells and hide them in the back of the tank. As the egg shells dissolve, the snails absorb the calcium through the water. Replace the egg shells as it dissolves away.
Great site for info on care:
http://applesnail.net/ ((for the most part) apple snail = mystery snail)

I LOVE our two mystery snails. They're awesome - I'm sure you'll love them, too.
