I had read it was safe don’t remember where
I recently tried it and didn’t seem to effect my tank
When I glued down the huge plant to some rocks
Hobby lobby had a ton of fake decor
I use it for plumbing as I can re-use parts with a hair-dryer or a bit of kettle-water.
That's dry in the filter cupboard, mind you - not wise to use electrics in or over wet areas
Hot glue is nothing more than a thermoplastic. It's safe for fish and is used in a great many tank decorations. Cures the same colour as the glue stick you use, so you won't want it to show much.