I've never seen my 16" Clarias move so fast - we are having swordfish for tea and the other half washed and dried the skin and suggested feeding it to the fish. I said to try the clarias (who will eat ANYTHING).
I waved a strip of swordfish in the tank he came over, had a sniff and legged it as far as he could! He cam back, had a nibble at a corner then hid behind the bog wood. I can honestly say I've never seen this fish 'scared' but at the smell of sword fish he $%it himself and ran away.