I think he's on about Pla Chon (snakehead fish), they are carnivors and can also "walk" from pond to pond (I think). I don't see that a few of them in a pond riggers size would be a problem.
I've actually introduced them into my pond as I'm not doing fish comercialy and they are one of my favurate eating fish. They wont take a well grown fish anyway but if you had an adult Pla Chon in there when you put the fingerlings in it would play havok.
The first year I stocked mine with 2000 Pla Dook and 1000 Pla Nin and was feeding them about half a kg of food a day, sold some from the shop ate some and gave loads away, probaly broke even on it. This year it's teaming with fish again and we have'nt stocked it at all, I'm not feeding them anything this year apart from stale bread and some scraps. I've put 20 Pla Chon in as when the fingerlings start growing a bit more there will be no where near enough natural food supply in the pond to feed them. My BiL also put about half a dozen turtles in there that he's hoping will gorw to make turtle curry out of
Get some plants in there and use some shit to "green up" the water. A light suspended on a pole over the pond is great as it will to attract insects in the night (obviously of you only have Pla Nin or Tap Tin dont bother as they are veggies). We've also got loads of Pak Bung growing in ours which provides food for us and the fish.
I fish with a net but with a rod and line and the pond stocked to those levels you'll probaly be catching fish every few miniutes