Dumb I know but can algae grow on fish?

[nfored]

I have this rescue Thia Silk and today I noticed a roundish brownish spot on him almost like the brown diatoms algae on the tank. I thought it was a Ammonia burn since I know ammonia can cause dark spots. So I checked the Ammonia and it was 0 under all the lights in the house except if I put it directly under a 2x odno t8 and then it was < 0.25 but that could just be a trick of that light.

I can't take a pic but here is a video.

[YT]FnXRwFjA_l4[/YT]

 

[mshill90]

Uhm, are you talking about the black spot on the end up the tail where the finnage starts?

 

[fishfreak2009]

Once, when my filter died on my old 90 gallon setup (a few years ago), I had cyanobacteria growing on everything. Everything included the veilfin koi angelfish fins...

 

[dempsey420]

nice fish, only FH iwould get.... as for the algae i have no clue

 

[nfored]

The best view of it is between 3 seconds and 5 seconds and its in the center of his body almost, or if you look at the picture of the video its to the top left corner of the play button in the center of the viewer. Maybe I am just worrying a lot I just know he came from a tank that suffered lack of water changes and he will only eat 2 to 4 hikari pellets a day regardless of when or how often I feed him. The only other fish I saw eat like that was my Oscar who ended up dying from a fight that shouldn't have killed a healthy fish.