Hi. I'm new to the forum and new to fish. I ended up caretaker largely by default, but have become attached to the little buggers. We have 3 large silver arowana, a small lungfish, and an eel that have happily coexisted for about a year now. In the last week, a couple of the arowana have developed inflamed gills. The tank was cleaned yesterday (we use a service) and today the arowana are listless and are not eating their arowana pellet food. The room that they are in smells badly as well. The lungfish seems fine and the eel is hiding as usual. Could the arowana just be reacting to the tank cleaning? They don't usually, but we've only used this particular service provider for the last month or so. How do I know if they're sick? What do we do? Help!! Thanks!