Im not really sure if these would be naga or mermaids...
Leech Naga
Info: Naga with very short, thick skined tails, it is a dark green which reminds some people of a leech, they hide in murky ponds and rivers and wait until a sizeable prey comes by
Attack: If they see a good sized prey they will shoot from the water, tackling their target to the ground and latch onto them with extremly sharp teeth, draining them of fluids in minutes.
Diet: They eat mostly blood and fluids, but if they are hungry they may rip a limb off their target and flee with it, slowly chewing it down
Hunting: Leech naga hunt in groups of 2-5 so they can overwhelm the target. Leaving the empty corpse on shore, sometimes taking a limb or two
Appearance: They have the top half of a cute 10 year old girl, but the bottom half looks like a giant leech tail, which is only a fraction of the length of a naga's tail
Intelligence: Most of them are smart enough to organize themselves before attacking, but choose not to learn intelligible speech.
Other: Naga and other large predetors that live near leech naga find it handy how they leave their drained victim on the shore, quickly swallowing it if its fresh enough
Some people have tried to capture leech naga for their own gain, but once the leech naga let out a screech, the others would quickly mutilate the captor