hey...how can you tell if the fish are getting enough oxygen in the water?? I have 3 (12") pacus in a 40 gal tank (I know the tank is too small) but they have Small patches of purple color on the side of there faces, close by there mouths. Now I work in the nursing field and if a persons face is turning purple...they are low on O2. What about fish? How can you tell if the oxygen in the tank water is right for them??
first tank I have ever owned and have had it for 13 months...I'm a newbie