A friend has 2 catfish in an indoor aquarium which he has to dispose of.

Wondering would it be ok to put them into my outdoor pond here in Ireland, 
they are about 6" long and my pond is about 1200 imp gallons (5000 litres) 
with about 20 fish already in it - Golden Orfes about 5", 
Goldfish,Shabunkins and Comets ranging between 2" and 4" long.