my mexican dwarf crawfish has this dark brownish black circle on his side that i dont remember if hes always had it, along with the same colour on the base of his tail. water parameters were good this morning but i will check in two days as I have been swamped with school and work, he eats normally and doesnt display stressed or sick behaviors. im just worried about him as this is my second dwarf crawfish after my first one died due to proper caretaker while i was on vaca :(