As well as my round fish pond I also built this small fish pond

[CapelOwl]

Thanks for your comments the wood is called "log roll" in the U.K. and is sold in most garden centres for edging , it's treated wood that's harmless to fish and can last about 20 years even under water.

[jodymcbeath]

I really like both your ponds, your round pond inspired me to build one, and I did. I was wondering what type of wood you used around the inside of the pond and where you could purchase it?