Wow you really went all out on the filtration. I am impressed. How long do you feel you can keep your arapaima's in this size of tank? I ask because I have 2 large tanks also and was concerned about keeping them in my smaller of the 2. I have owned an arapaima up to 3 years ago. She was 5'5" long when she was attacked by a tankmate and died from her injuries. She weighed 126 lbs and was nearly 4 years old. What are you presently feeding your two beauties?