You will want to get a sponge filter, a bio wheel type hob filter, or some sort of filter media that can breed nitrifying bacteria. If you have a sump, I would put one of the aforementioned filters on it, and let it run for at least 2 weeks to gather some bacteria. Then siphon out 10 gallons from your DT, and put some pvc piping into the tank for the fish to hide. Have an airstone and pump ready in case you have to use medication as it usually depletes oxygen in the tank. Also a very reliable heater. And be ready to do lots of water changes if you don't have the tank cycled like mentioned above (the 2 weeks).