Algae growth on fish

Question
I have a male betta in a 1 to 1.5 gallon brandy glass.  Over the last 3 weeks a greenish algae has slowly grown on his body.  I have been doing regular weekly water changes and alternating with cleaning the tank, rocks, fake plant, and hide.  I treat the water used with Prime to remove chlorine and such things that also provides a stress coat.  The growth on the fish is still there, what can I do about it?

Answer
Jessie,                                                       Stop using Prime. Are you using city water? If you are just use a mild dechlorinator , like tetra tap conditioner. I am a firm believer of using s little chemicals as possible. Let them live natural. Your betta has a gusto for life and is very hardy. No need to stress coat him every week. If you are really worried use bottled water or just leave your water out over night. Clorine will evaporate. Do this and the algea should disappear. If it doesn't i would medicate him with a little erythromyacin for a week. That should take care of it ..... Good Luck , Tina