Ok so I went and purchased an Oranda goldfish today from petsmart and I noticed that it has a red vein going through its caudal fin and some people say its caused from poor water quality (which is understandable, considering there were like 6 of these guys in a 10 gallon tank). Anyways, here are my water parameters Ammonia: 0 Nitrite: 0 Nitrate: 5.0 ( my aquarium isnt cycled) but I will do frequent water changes to keep those things down. My temp is around 78-79 (I know they prefer colder but I originally had a jack dempsey in their for like 3 days so I had the temp a little high). I have added prime water conditioner. I have Api pimafix and rock salt thats safe for tanks. So what should I do?