I have only seen 1 pair of fighting arowanas. The Jardini, almost killed the Silver, when the Jardini was about 5" and the silver about 7". But you should separate the species from Asian and Australian, because they are very different.
The Jardini is from Australia, and costs about 50 dollars in my country(Norway), and they are very agressive..
In the Asian types, the green ones is known for beeing very agressive. Thats why lots of colourful Arows mates with the green one in ponds,( like in Thailand and Malaysia) because the male carries the eggs in they`r mouth. And the females often see the green ones as the best defenders of their eggs.
By the way, the cheapest Asian Arowana costs about 400 Dollars here in Norway..
A super red one costs about 4500 dollars, here in Norway...
Best regards
Pikefisher