Parrot avaiy over fish pond

hello,

i build koi and goldfish ponds, but this past week i saw a customer who
has a avairy for 7 parrots over a small fish pond,
couple of questions,
1. since this is a inclosed cage 30 x 10 or so with a 12 x 12 pond
first is it safe to have koi and parrots within the same enclosure regarding parisites or bugs from either effecting the other

also they stated they wanted some kind of wire or net, that 1 the birds nor the koi would get stuck in and die,
2 is soft enough to protect any parrots that cant fly from drowning,

lets start here, any suggestions
thank you
dan esposito