I was just feeding my Betta fish last night, and I noticed looking at his tail that he has minute black spots all over it and his body etc. I'm not sure if this is a disease or what, as I can't remember if I have recalled them before. He is very very active, eats normally etc, and I have a filter, heater etc and everything is right, I feed him daily and he doesn't share a tank with anything else.

Housing
What size is your tank? 50L
What temperature is your tank? 26C
Does your tank have a filter? yes
Does your tank have an air stone or other type of aeration? the filter.
Is your tank heated? yes
What tank mates does your betta fish live with? Himself
Food
What type of food do you feed your betta fish? BettaMin Tropical Medley
How often do you feed your betta fish? once nightly
Maintenance
How often do you perform a water change? once weekly or every other week
What percentage of the water do you change when you perform a water change?50%
What type of additives do you add to the water when you perform a water change? conditioner, and sometimes eco-control
Water Parameters:
Have you tested your water? If so, what are the following parameters?
Ammonia:
Nitrite:
Nitrate:
pH:
Hardness:
Alkalinity:
Symptoms and Treatment
How has your betta fish's appearance changed? Not visable, but looking up close is tiny black dots. (Not sure if pattern or disease)
How has your betta fish's behavior changed? It hasn't.
When did you start noticing the symptoms? Well, I looked up close and saw them last night.
Have you started treating your fish? If so, how? No.
Does your fish have any history of being ill? He had an extremely minor case of fin rot when he was bought from the store but I treated him
How old is your fish (approximately)? I think a year or so?