My Big Red Tail Golden Arowana (RTG)

This is my big ass RTG Arowana its a monster he/she? is only 4 years old we did have a 180 gallon tank but i had to switch to a 120g its alittle small but atleast we didnt sell him/her?. The tiger fish is really cool it changes colour fast to yellow and black stripes but he is not sick he dose like that when thers light or daytime when its dark he starts swimming around. I doint know his age but its the biggest one ive seen (ever) and only got him for $100 with the arowana is $1800