Many people like having more than one Arowana in the tank , that 's fine and all but they must be at least 5 - 6 or more in the tank at a time because Arowanas are very aggressive towards each other .
Many people like having more than one Arowana in the tank . 
 That is not a problem , but there must be at least 5 - 6 individuals per the tank because Arowanas are very aggressive towards each other .