I paired up my retics this year for the first time. The male was aggressive to start and really chilled out after being with the female. I'm pretty sure it's because my female is super tame and he learned from her that I'm not a threat. I've heard that male retics can get aggressive during breeding season but I've experienced just the opposite, both my male and female are really laid back now and I'm in the middle of the breeding season.
Where did you find that photo? It doesn't even look like a snake bite.