+ 1 on what acropoorer said. no need to dissassemble tank,dip or poison. They really arent harmful. However they do seem to thrive where there is an abundance of crud and no natural predator present. I would 1st look at the way the tank is set up and try work on areas that trap detritus, low flow ect.And 2nd I would try a predator like the chromis dale mentioned. I use a green wrasse (he is a killer). I tried a six line in the past(its what everyone reccomends) he wasnt much of a hunter.