Hey Renee,

Tadpoles themselves do not tend to import disease, though they should be quarantined, just as any new wildlife would be.

The two major problems with tadpoles in a koi pond are: 1) koi look upon them as a moviegoer looks upon gumdrops. Yummy. 2) most petshop tadpoles are bullfrog tads, and bullfrogs are a damn nuisance. They are apex predators in a batrachian milieu, and when mature, will eat anything they can get into their mouths. Considering a mature bullfrog can grow as large as an average dinner plate, that includes small birds, ground squirrels, goldfish and small koi. The only thing that keeps the monsters from ruling the world is that raccoons consider them delicious, which is about the only nice thing you can say about a raccoon in or around your pond.

If you want frogs, make sure that the tadpoles you import are green frog tads. They are exclusively aquatic, do not wander, and are strict insectivores.

They make great neighbors.