It's not the breed that matters... it's the number fishes and the size of the enclosure.
If your enclosure is big enough for 2 arowanas to mark out their own territory and avoid each other, they can co-exist. Such an enclosure has to be huge... a standard tank that will fit in a house will never be big enough.
If you have 2 fishes, there is always one stronger and one weaker... the stronger will always target the weaker one until it dies or leaves (jump out). Arowana keepers recommend 5 or more arowanas in a tank. In such a setup, the dominant one has to pay attention to 4 other fishes that want to topple it from grace. It cannot afford to keep bullying one fish till it dies or leaves. Even then, there is a lot of heartache involved, as the setup does not prevent them from fighting, only prevents the fishes from fighting to death. Many people report torn fins and tails, and dropped scales on all their arowanas... something few people can bare to see on their precious fishes.
This is the setup for any kind of solitary territorial fish, if you want to put many in one tank. Even for fishes as small as Rams and other dwarf cichlids.
For arowanas, sub-species play a part too. I'm told the RTG is the most aggresive (also grow to the largest, IIRC) and the reds are the least. That's why many people who want to try community arowana tanks choose reds.
My personal experience: My fish was the sole RTG in a 4ft tank with 3 reds at the LFS before I bought it. They were all of comparable size, around 6 inches. My RTG had the run of the tank and the 3 reds were crowded in one corner. If they tried to leave the corner, the RTG would give it a quick snap to chase it back into the corner.
Bookmarks