you can get away with adding one later but they take the rubbish off the surface.
i would stock very lightly two at the start then when the filters are coping stock bit by bit to keep costs down buy young 1 year old fish which you can watch grow
__________________ http://www.ukkrazykoi.com The internets fun helpful koi forum. 
1x 3255 gal pond
1 x nexus 300
1x 3kw electro heater
2 many litres of air per minute to count
1x sequence 15000
1x aquamax 5000
| 
