I love BIG FISH!! I don't know wich one of my fish I like the best. I have a 6 mnth old Pacu who is allready about 15 inchs long and 12 inchs tall, he's great. And very friendly. Also I have an Arawana who is also about 15 inchs long. What a great sleak swimmer. He is very intriquing to watch! I also have two Clown Knives. One is about 8 inchs and the other is about 18. There fins move in a very smooth wave and there colors and spots are awesome!! I hear if you give them the room they all could be 3 to 4 feet long. I plan on upgrading to a BIGGER tank SOON!!