i just noticed a raised scale on Osiris (copper dt) he does have a deformed spine but the spot is on the top half (leftside when facing me). not nearly 1mm high. his spine is a tad bit worse than the other dt but he has no issues swimming. i got him from an lps a month ago. i dont have a camera nearby atm. i dont suspect a tumour just yet but just how fast can a tumour manifest for betta? hes in a 2.5g water 24c heated, not filtered.
this is not my betta but looks 90% the same
i used paint to mark the area of the raised scale (no photo shop). the mark is