I keep my 4" black with sunshine plecos. Below 6" ish, arowanas are fragile and afraid of sudden movements/tankmates. Overall my black is still shy when I approach the tank...except if I drop some pellets in then he swims right up to the front.
Well my jardni was skittish from 3 inches to around 7-8 inches and then she really warmed up to me and even my family. She always greets me and runs up and down the tank like a puppy at 16 inches. Its really nice to be greeted every time I see her no matter how much I feed her haha. Shes really calm and full of excitement when she sees me which honestly makes my day every day haha. When I do a w/c on the 220 I sit next to the tank when its filling and she never leaves my side. Honestly the bond between my jar and myself is very close and I love it!
the silvers i've raised before are pretty skittish, i left a lamp type light on next to them 24/7 and the light seem to help them calm down. they're more shy and jumpy when they're little but when they get bigger, any fish that can fit in their mouths become snacks.
i have a 4 in jardini now, he seems like an *******. just the way i like my fish.