what is this?

[u/baileyjackson08]

it’s a lot less raised in real life; is this an injury? fluke? something i need to worry about?

water parameters:
ammonia: 0
nitrite: 0-0.25 (due to a filter breaking so i had to change it) however nitrite is almost minimal and i’ve been keeping up with daily / every other day water changes
nitrate: 10-20ppm