Goldfish Compatibility

Question
Hi, I have a 30 gallon tank with a heater and really good filter that I set up about 4 months ago.  Right now I have 4 goldfish that I put in right in the beginning.  Except for some torn fins, they are all healthy.  I only have fake plants, and a couple rocks as decorations.  I would like to add a couple more fish, but do not want to get rid of the goldfish.  Which fish would you recommend to add?  Thanks for your advice  :)  

Answer
Hi Noralee;

Your tank is actually maxed-out with four goldfish in it. I really can't recommend adding any more fish. They are pretty messy guys that get to be 6 to 8 inches in just body length, not counting tails. Each one needs at least 10 gallons all by itself. Make a partial water change of 25% every week and vacuum the gravel too. If you haven't been changing water weekly already, that may explain the tattered fins. It's a common problem that most people don't realize is related to water quality. Most people also don't know that weekly changes are so important. Their fins will probably begin to heal and regrow with plenty of regular fresh water in there. Doing twice a week 25% changes for a couple of weeks will help get them in shape even quicker. Then just go to the once a week schedule from there.  

Goldfish are also cold water fish and like their water at under 72f. Set the heater low enough that it stays below that. If it stays too warm for a long period of time, goldfish become weak and develop disease quite easily.

Here is a good profile page about goldfish to know more about them;

http://www.firsttankguide.net/goldfish.php

At Your Service;
Chris Robbins