I bought 2 silver arowanas 4days ago from craiglist the guy had them in a 130 gallon aquarium. They are 24in+++ 3years old he said they get along very fine . I took them from him and released them into my outdoor pond. My pond size is 15ft x 9ft x 4ft. Today I went to go check on them and realized that when they went near The water fall they would sorta chase each other. But when there away they don't chase each other why is that?