When water in a tank have any salt, it will foam up on the return. That is what it looks like but I could be wrong. I do not see the real problem yet with that fish in the current tank. Many people keep fishes such as Arapaima, TSN, and RTC. Many of us did it in the past, currently doing it, and may do it in the future. There is plenty of people with a larger tank that are willing to re-home the fish for a reasonable fee. Free would bring in irresponsible people. Some people look at the moment and some look too far down the line. As long as the fish is taken care of properly and don't show signs of stress, the is the main thing . If we want to blame anyone, we have to start with the people importing and selling them for a profit.