Loss of my first goldfish

My first goldfish died this morning (suspected bullying from his
tankmates). While i plan to eventually get a successor (who shall be
known as Dante II) I'd kinda like something fixed as a memorial.

So what are the rules for tank ornaments? I cant really engrave a stone
myself or anything, and im guessing permanent marker is out of the
question, but I'd like to do something to remember him by. He was the
first fish I got, and my girlfriend and I picked him out at the shop. He
survived initialy bad water, attacks from a paradise fish named Outis,
moving flats, moving tanks but eventually it seems to have caught up
with him. The things I learnt keeping him are being put to good use with
my other fish, and he was a lovely fish who got me into keeping fish to
begin with.

Any suggestions for what I can do?

sincerely
Adam

p.s. I really am serious about wanting to do soemthing for my fish and
would appreciate any suggestions anyone cares to make.