At this point, I agree that you should take the feeder goldies back. I also suggest that you leave the same water in the tank and let your filter run. Knowing goldfish the way I do, there should be plenty of ammonia in you tank for cycling. Do get a test kit to check for ammonia, nitrites, nitrates, and ph. If the kit also has tests for other things such as gH or kH makes no difference at this stage. You can go ahead and test for ammonia right away. Don't worry about testing for other things until the tank has been cycling for 2 weeks. Then test to see if there are any NitrAtes...not nitrItes. Then if you find nitrates, come back to the forum and reveal the reading. If they're high, you may need to do a partial water change and test it again. Do a ph test too and report it's level as well. If nitrates are good and ph isn't too low, you can start adding fish slowly. When you take the goldies back, look at other small fish that you may like such as fancy guppies. They have very colorful tails and stay pretty active. There are also mollies, swordtails, striped danios, and others that stay very active. As long as you tank is nicely decorated with plastic plants, rocks, ornaments, or whatever items you like, keeping only 5 fish that stay active will give you a nice setup with plenty of pretty movement of fish. There is no need to overcrowd an aquarium to have a nice beautiful aquarium. And do get rid of the goldies before they start dying from ammonia poisoning.