
My 8-9" arowana has a great appetite (eats live mealworms and frozen shrimp), behaves normally, and swims confidently around the tank. The water parameters are all great (nitrite/ammonia = 0, nitrate < 10 ppm, ph = 7.0, chlorine = 0), except that I have hard water. I use city water, and since I live just outside Houston, who knows what is in my tap water.
The problem is that he has ragged fins and has had them for months. Every fin is a bit disfigured. His tank mates are 1 ornate bichir and 7 black skirt tetras. I have never seen the tetras behave aggressively with fin nipping, but it has crossed my mind. Alternatively my aro has never acted aggressive with them (I suppose its a matter of time for them though, especially since my 5" bichir is already making lunges at them from time to time). The bichir and aro are a match made in heaven.
Any ideas whats causing the fin issues? I have not noticed any whiteness in the fins or spots. I don't thin its disease, because he has had the symptoms for months and has always kept a robust appetite and good relaxed swimming behavior. Occasionally he gets stressed and spazzes out, especially when I vacuum/water change. He also is afraid of the dark, because when I enter the room and it is pitch black, he sees me and freaks a bit. I suppose I should get him a night light.
I think it is something in the water. Any thoughts guys and gals?

