Single white spot on cardinal tetras, help diagnose please?
Am new to this forum but came here to seek some advice. I have a 75g dirted, planted tank which completed a fishless cycle, was left for 3wks to ensure stability. I had 15 cardinal tetras in a 1yo tank which I transferred to the 75g about 2wks ago. Solo occupants of both tanks except pond snail hitchhikers from plants and 2 assassin snails.
Temp is 80-F and water parameters good for ammonia/nitrites/nitrates(0/0/0) Eheim 2217 filter, air stone.
Today I notice half of them have a single spot on their causal fins. It doesn’t look like ich. The other half have no spots. I enclosed some photos.
Anyone able to advise what this is? Just in case it is very early ich I am starting to raise temperatures now. (And where could it have come from??)