Well, since player choice (for main character, if you edit files to allow all races) and game settings (for randoms) can allow characters to be male or female, meeting a male mermaid or having to program in two species names depending on a character's current gender might be a little odd to some players (or at least to the game dev). Sure the mythological nereids were apparently all female too, but most people aren't going to know, notice, or care about that.why call it nereid then? it's like saying magick instead of magic