Another way to start a cycle would be to add fish food to it. As it rots, it creates amonia. The best would seriously use the water from the other tank and the filtering media as previous stated. Go to store and get something like Stability from sechem. It adds a boost to the bio filter. I have used it and it does quicken the entire process. Only add fish now if you want to risk killing them. Snails do not like any amonia. It will kill them, and then they will secret something that kills any other inverts in a tank. How long have you actually had the 3 golds in the 5 gallon?