I believe you usually add a piece of meat if there is no fish in the tank (I could be wrong) But I've always heard you can put a piece of meat in because it will decompose and then build up the good bacteria you want to have in your tank. If you have fish in your tank, there's no need to put the piece of meat in, as they are giving off the waste that will do the same thing as the meat. I agree with some of the others, try to get your fish into a bigger aquarium as soon as you can. I have 3 fancy goldfish, in a 55 gallon and I do 25% water changes about every 3 days because they give off so much waste. Cycling your tank with them in it won't be a problem, just make sure you keep an eye on the water. If you can, go get a test kit that will help you see if the ammonia (that the fish give off in their waste) in your water is too high. This will help your fish while you cycle a tank. If you are borrowing a tank, make sure you rinse it out really well first. Do not use soap to clean it! Any soap left in a tank will harm your fish, it is better just to rinse it or use REALLY diluted bleach (your tap water purifier will pull any tiny bits of bleach left over out since it removes chlorine). One more thing for you.... goldfish are cold water fish.... so everyone keeps saying to get a filter because if the temperature in your tank is above 74 degrees, your goldfish are going to have a hard time breathing. Adding a filter that will move the water around will send oxygen into the water which will help your fish. For goldfish, when you get a filter, you want to get one that is for a tank bigger than yours. I personally have two filters on my tank that are both for 55 gallon tanks. Thats some of my tips for you. Good luck!