Thank you all for the compliments! The tank was 3m long, 80cm deep and had 70 cm water height. The Aro mostly ate dead food like artemia and other normal discus food, dry foods and sometimes a guppy or cricket. I had a 1,50m sump underneath and did lot's of water changing so the water was always clean. Also no drop eye on the aro witch I am convinced is because of the better water quality compared to lot's of predator tanks. I sold the tank also but when I'm back I will build a little bit bigger one for fwstingrays.