I agree with Hara. Starfish are interesting inverts and they should do good as long as you feed them regularly. In fact I had one in a 10 gallon invert tank for about four months and its doing great. I feed it pieces of clam and shrimp and it absolutely goes crazy over these foods. Mine is tan in color and has relatively long arms. Best of Luck!
Fishkeeping is a great hobby and very rewarding to say the least, both fresh and saltwater equally. A few good tips for success: ALWAYS quarentine new arrivals for AT LEAST a month before adding them to your main, always maintain your pets accordingly, feed varied diets for top notch health in your animals and enjoy them. I wish you all the best of luck!