KNOW I HAVE A 84GAL WIT 6 5"BALASHARKS 2CLOWN 3" 1REDTAIL 2" & 1PLECO 5"...COULD I ADD A arowana .& SOON B GETN A 180 0R 240 GAL
IF I GET ONE IT WOULD BE 4"
Realize this, a 4" silver aro will be 16-20" in about a year. I don't know the dimensions of your tank but at best the aro will need a larger tank in 9-12 months. If you got the 240 gallon that is 8' x 2' x 2' the aro could live quite comfortably for 4-5 years eventually this fish will grow beyond 30" and is going to need an even larger tank. If you were to go with a 300g wide 8' x 2.5' x 2' probably could go ten years or longer.