bug on my fish

Question
i have a bug on one of my damsels, its about 1/4 inch and looks like a silver fish attached to my fish

Answer
Ok that sounds like a parasite infection most parasites live off of excess waste and food. To kill the parasites i would use "General Cure" by API. In addition to the medicne start doing weekly water changes of 25% so all the ecess food and waste doesn't sit in your tank and rot.