I have a 200litre approx 50 gal tank. All the parameters are in place with regard to NO3 NO2 GH KH PH and CL. I have 5 Angel fish 3 elephant nose and 4 Ghost Knife fish in this tank. I recently added the GKF and the Elephant noses and have been feeding them blood worms. Now I have noticed that the Angels all seem to have a red line forming on their bodies just under their fins. On the VT angel the ends of its fins also have a red tinge to them. Does anybody know what is causing this? The fish seem healthy. Is it maybe because of the daily dose of blood worms they are now getting along with their standard food?