u/Serious-Being-5267

So one of my 4 vampire crabs passed away unexpectedly. This morning i found him not moving next to the food bowl. And yes i am sure this isn’t just a molt. I’d love to preserve him, put him in a cloche and place him on a rock with fake plants around him. I have taxidermied butterflies before so I am somewhat familiar with the process of pining. My question is more how do clean out his shell so he doesn’t just rot? Right now I have him placed in 70% isopropyl alcohol in a small glass jar with a cork lid. Have i done the right thing?

Noticed this lump on my 2 years old fish’s chin about a week ago and it does seem to have grown a bit since and i’m worried it might be a tumour. Anything else it could be? He’s in a 22.5 gallons planted tank with some red cherry and crystal shrimps all my water parameters are perfect and temp is 78°F. He’s still pretty curious and active, eats and seems to be swimming normally. So what’s this weird lump?