TSN's are more picky.. but are true predetors ime... my TSN prefers live food to dead every time.. But if yours is fine with smaller fish he may also be fine.. there really is only one way to find out..and the bigger the arrowana is the better. If you have rock-work decor ect in the 800 you may try adding or subtracting things or moving them around before adding the arrow.. they will often help disperse territorial tendancies in other fish but also change up the LOS and throw your TSN off abit until the arrow settles in. You may also try moving the TSN into the 180 for awhile and letting the arrow establish itself in the pond.. but tbh at those sizes you've got enough water volume imo to let everyone have their space. I will be moving my 12" RTCxTSN and 14"+ TSN into a 1,100 pool in the next few weeks with my group of gar 16"+ and worry more about fish jumping out ( like unfortunately happened to your other arrow) then predation at this time... I'm sure in the future I will have concerns..But whenever houseing ANYTHING with bigs cats it's a gamble. I've seen pond/pools with big cats and oscars that are just fine, and others where the only thing is big cats because they eat anything and everything includeing other big cats on this site. and others where they do fine for years with tank-mates then suddenly tolerate nothing and no-one with them.
