I read your other posts about your tank. I'm glad that you care, and I am willing to bet that once you get him into a clean, heated tank he will surprise you with some beautiful colors. My parents were pretty bad too (they thought you can clean a tank every 6 MONTHS) and even they notice that my fish look really good and will even comment "wow, he's really colored up since you got him" when I bring home a new fish. You will also notice that his fins will spread out and appear bigger...one of the plus sides of having a well cared for fish is that they are more beautiful ;)
For now just keep the water clean with regular (every other day to every day I'd say, but someone more familiar with uncycled tanks may be able to help you better) water changes and keep him in the warmest room of the house. Remember to use a water conditioner and slowly acclimate him to the new water during the changes.
Feel free to ask any questions you may have, and good luck!