Best setup for Hydrolycus Scomberiodes / Payara?

[Svampus]

Hi guys, im getting 2 Hydrolycus Scomberiodes this week. They're about 5.9 inches and are eating fish fillé more or less. At first they are going to be placed in a grow-out tank at 59 gallons (222 liters). Then, when theyäve grown a bit they will move to my 395 gallon tank (1500 liters).

How should i setup that tank? Slow or fast-flowing water? much filtration? many waterchanges? much/little decorsations? many hide-outs? plants?

Thanks!