Hi,
I wanted at least two large angelfish in my 190 gallon so I chose two of the more mellow angels. I got a Majestic and then put a Scribbled angel in there. Both of these fish are some of the least aggressive large angels, and both only get to 10 or 12 inches. For the first week the Majestic chased the Scribbled a little and it keep out of the Majestic's way and let it keep the most dominant role in the tank. Both of these fish are about the same size. A Scribbled is suppose to be easier to keep than a Regal which they say is very difficult. I wanted to get the second angel put in the tank to be a little larger as is recommended by my book on angelfishes. It says to put the least agressive and smaller angels in first and usually not to mix with an angel of the same species.
If you get another angel make sure that it is at least a couple of inches larger than the juvenile koran especially if it is of a less aggressive species. It would have been better if the angel you have now was of a less aggressive species if you wanted to mix angels as Korans are suppose to be some of the most aggressive angels out there. I also had a Goldflake angel in with the Majestic at first and they got along great. The Goldflake died from worms after a month...had long stringy poop from the beginning (highly suspect for worms), but it was eating well at first. When it stopped eating I took it out and tried to treat it but it was too late.
I highly recommend a book "Angelfishes and Butterfly Fishes" by Scott W. Michael. You can go to amazon.com and get one cheap used, or go with a new one if you want. I got one that was used and like new for a really good price. You would really like this book and it may help you. I have thought about maybe getting some type of butterfly for my 190 fish only live rock tank, or maybe putting another medium size angel like another expensive Goldflake or a red sea Regal later after the tank has been up longer. I really like Majestics as they stay under a foot and have a good temperment and I have found them to be almost as hardy as a damsel if you get a healthy one that is eating well from the beginning. If you want a healthy fish that is eating well go the liveaquaria.com and get fish from the "divers den" section as they are wormed, made sure they are eating and quarenteened before they are sent. I have always had luck with them and they have a picture of the actual fish you are getting. You may pay 25 percent more for the fish in the "den" but it is well worth it. Good luck and keep me posted as I love large angelfish and would have one of every one if I could. My majestic and my scribbled share the tank with a Potter's pygmy angel, a couple of wrasses, pair of clowns, two blennys, a cleaner goby (you need one of these...great to keep the parasites of angels), a royal gramma.....and I plan to add one more fish in a few months....maybe a Regal or a Banner butterfly, or another Goldflake. I agree with the other poster that the Emperor angel fish gets too large for a 180...to 16 inches. Your Koran will get to almost 14 inches which is almost too big for a 180 when full grown. Good luck, Lesley
