The research team studied 13 male Siamese fighting fish across five different housing conditions ranging from 1.5-litre jars to 19.3-litre aquaria, both with and without environmental enrichment.

With Kinman fighting the fish with heavy tackle, and Leonhardt holding the rope to the dart, the anglers had two lines to battle the giant swordfish – which still took 90 minutes to subdue. Sign up ...