I have a fire eel (Mastacembelus erythrotaenia) around 16 inch , 2 days ago he started harrasing my bumblebee cat so i fed him plenty of earthworm's to keep him happy . Unfortunately i think i fed him too much at once & he now has a swollen anus , i can't see anything wormlike or other around it & he is as active as he usually is but after reading a little i realise that just because i can't see anything that doesn't alway's mean it's not a parasitic problem . Unfortunately i can't get a picture , i tried but he is not playing . Could the swollen anus just be from me overfeeding him & maybe now constipated & is this a big problem ?