Fish SPA

Me and hubby tried the fish spa at queensbay today. The charge is rm25/person for 30 minutes. The moment I dipped my foot in the water , I screamed. I was shocked because all of sudden my foot was surrounded by school of fish and the are like piranha. i retract my foot and put back. After some time it feel good. I had the session about 1 hour ago, and now O feel so tired. I still can feel something with my feet. This should be the effect of the fish spa.