I use them for eels and the vast majority of fish have been hooked centre of the lower jaw. I get rid of the barb,not necessary IMO and if the eel is a smaller one it's a doddle to grasp the shank with forceps and twist the hook out. I do this over the water and the eel drops back in without seeing a net or the bank. Win-win AFAIC, no hassle for the eel, no slime for me.
I use them with lobworms which I kill first and then add a small bit of elastic band to help keep the bait on the hook.
Keora: How do you rig for pike fishing? I'd like to try this mice elf.
For medium size smelt I use a Mustad Demon Circle Hook size 3/0 crimped to about 15 inches of 30 lb trace wire. I've not seen made up traces in the shops so it's a case of DIY.
I use 10 ft Drennan pike rod and a small bait runner with 30lb power pro braid.
Tie a sliding stop knot on the braid with 10 lb nylon line.
Slide a Drennan Zeppler float onto the line. The 20 gm float is a good all round size.
Slide onto the line a 20gm weight - I use drilled bullets because they are cheap.
Tie a cross lock swivel on the end of the braid.
Clip the trace you've made up onto the cross lock and away you go.