Oscars and Saratoga Leichhardti in a 280 gallon tank

[Hello fish keppees]

Hello
i am looking at buying a leichardti arrowAna and have a 6X2.5X2.5
i have 3 oscars, 2 gold Severum,a polleni, a sailfin pleco and five tapais geophagus. All these fish are around 10 cm right now.
Any help would be appreciate.

 

[Hello fish keppees]

I also have a 4 foot sump which adds about 50 gallons of water