About fifteen kilometers west of Khanom, there is a small stretch of river known for its fishes eating dead skins. Several places opened there in a few years and offer visitors to sit on their benches on the stream with their feet immersed in the water while the fishes are eating their dead skins. This is the principle of fish spa as we often see it in Thailand in shops with aquariums except that here the fishes are free. I must say that you should not be ticklish otherwise you will probably not manage to keep your feet in the water but the setting is nice so even without doing fish pedicure, it's nice to sit here. I put the GPS coordinates of Suan Ta San which is my favorite fish spa place in the area. I prefer it to neighbouring Ton Tarn Resort & Spa which is where the pink dolphin tours + Khao Want Thong cave
usually take you because with its many bungalows and waterpark, it's not at the same ''nature'' atmosphere. But with children, especially if it's hot, the Waterpark can be a good option...
I know that fish pedicure is controversial because there have been some cases of infections and some see it as cruelty to animals and personally, that's why I never pushed the door of any indoor place offering it. I did not studied the question very deeply but with fishes in freedom in a natural river, I tend to think that the inection risks are lower and fish inevitably happier. Anyway I invite you to read this article about the dangers of the fish spa. And then you will be able todecide whether you go there or not. Note that there are restaurants in both places and more people on weekends and holidays because customers are mostly locals.