White Spot?

[nathan01]

i noticed that on a tetra or barb, the fin has white on it, and just now on of the fins had dropped off, what do you think i should do.

I tried posting a pic but didnt work

 

[WILDER]

How many gallons is the tank.
How many fish and which type.
Water stats in ammonia,nitrite,nitrate,and ph.
White spot looks like they have been sprinkled in salt.
Is the fish strugging to swim with losing the fin.
On the fin does it look like salt spots, or bleached out and fuzzy.