I'm so sorry longmvu. Its too bad that you didn't follow the suggestions everyone has given you. ADF's are VERY sensitive. They do not have scales, meaning they have no protection against water pollution, certain medications, ammonia.... They are very difficult to care for and not something I would ever recommend for a beginner.
If you want to use your aquarium for something, how about a planted tank? Learn about aquatic plants! You can still use your tank and heater and filter. BUt you don't need to add fish. There are lots of different things that you can do with planted tanks, all sorts of plants from different regions of the world. You can create an african tank or an american tank or an amazon tank. All sorts of possibilities. Once the tank has been up and running for a couple of months, maybe add a couple of nerite snails. They are very beautiful and nothing will suffer.
