Most ofter its just a gentle bite. Maybe once or twice I got a bite that felt like a hard pinch on the inside of my palm. They were real hungry that time and the bite made me want to pull my hand out of the water. As far as their sucking power, the large one can pull stuff from between the upper part of my fingers from an inch or two away at the tips. Real cool.
120 gallon planted aquaponic tank with 10 clown loachs, first one since 1994, 1 modesta and 3 striadas.