There isn't a lionfish spear that will not hurt the coral if you hit the coral with the device. You might want to look at the FOOLS (Fraternal Order Of Lionfish Slayers) device as it was designed on the island and is accepted by the Belize fisheries Dept.
The spear alonf with the catch bag have been the most successful items so far in the eradication of the lionfish.
The Fisheries will allow hunting lionfish with scuba only if you are using a approved spear.www.liofishfools.org
Fools also teaches a PADI and SDI specialty course. on San Pedro contact Venancio Tillett 626 5217