More fish people!
Two monstrous humanoid HD mean we're off to a good start. The ability scores are all +2 or +4 increases, except for charisma. Sahuagin also get +5 natural armor, two talon attacks, a bite attack, and two rakes in water (out of water, rake functions normally). They also get Multiattack as a bonus feat.
But wait, there's more! Sahuagin have blindsense while underwater, can enter a blood frenzy (Rage lite) once per day, and can communicate telepathically with sharks. They also gain various skill bonuses, but most of these are quite specific (+4 on Handle Animal when dealing with sharks?).
Of course, they also come with a few drawbacks. Sahuagin can only survive out of the water for a few hours at the time, and suffer from Light Blindness (which can't be mitigated with Sundark Goggles). On top of that, they may become fatigued upon entering freshwater.
Considering these penalties (which make playing a sahuagin anywhere else than in oceanic depths quite impractical), as well as the utter lack of support for sahuagin anywhere, I think a LA of +0 can be justified here. Discuss!
At the very least, two extra limbs mean a damage bonus equalling you strength modifier on every attack, and that's before going into multiweapon fighting, pouncers, and precision damage. A +1 is in order here.
It's a sahuagin that looks like an aquatic elf, which means that it's trading natural attacks and a third of its swim speed for more time for extra-aquatic trips and a lower chance of getting chased out of towns by mobs. +0 LA.