the pond is on 13 acres. it is spring-fed, u can feel the cold water coming up from the clay bottom. its been there along time. at first there were only shiners and bullfrogs. actually i had some larger pine trees on the back of the levee cut down bc they were shading the bald cypress and dawn redwoods that i planted on the perimeter and it started losing water. around 4' in the middle now bc its so low. how big would the koi have to be? the bass are 4 years old, ive caught some that are 3-4 pounds and their mouths were huge. also some of the channel cats are 8 pounds. i have a 100 gallon goldfish tank with 3 4" koi now. also i was worried about herons bc they do have some of different species including the great blue heron. which ive known some people to shoot at their ponds but i would never ever ever shoot any wild animal unless it was absolutely necessary. maybe i should only use the calico color koi so they have some type of camo? im really dreaming of having koi 2 feet long feeding like my carp, it would be like the ponds at some japanese resturants but i surely dont want to purchase a foot long koi for 45$