Actually, we keep venomous fish almost exclusively, and we use the soft, open-weave "box-bottom" nets. Believe it or not, just as what happened to your fish, the gill spines are what always get caught up as opposed to the dorsal spines on these fish. I've had to cut a few fish out of nets before we came upon using the "soft" nets, and dodging dorsal, pelvic, and ventral spines doesn't make it any easier.
The material of these nets is either white or black. Taams makes the white ones. The other thing that's nice is that the box bottom doesn't close up around the fish, which helps prevent their spines from getting caught. FWIW, I've never had a fish become caught in one of these nets.
HTH