royal im not trying to start a argument but if a ball python can digest bones,a bit of aspen is harmless.imagine wat they consume in the wild.and btw,you should always supervise the feeding so if you see something like aspen getting consumed you can tend to it.

as for the OP,when did you change its prey size?even though you might have bumped it up,the snake needs to catch up and a few feedings isnt gonna help so quickly.personally when i feed im not satisfied unless i can see and feel a difference in the snake.a slight lump in its belly is good.i know it can be hard to get the perfect prey size but if you cant find somthing big enough try 2 smaller ones.most likely your snake will not show interest in a second if it is full.

as for the hissing,dont let this get to you.if you do the snake wins and will continue with the bad attitude.

good luck!