I'm an amateur guitar player and this song uses chords that I am unfamiliar with. 
I could be completely wrong about these chords, but this is what I hear when I 
listen to it and I can sing the melody over these chords and it blends beautifully.

The chords in this song are strummed using only E, A, and D strings while keeping 
the three higher strings G, B, and e muted.

chords used:

E (022100@1)name="chord_x02220@1">A D (xx0232@1)name="chord_320003@1">G B (x2444x@1)name="chord_022000@1">e
G:  3-2-0-x-x-x
A:  5-4-2-x-x-x
D:  5-5-4-x-x-x

Black Mermaid by Esthero

G (320003@1)  A (x02220@1)  Di'm (xx0232@1)a black mermaid
                       G (320003@1)  A (x02220@1)  Dfrom (xx0232@1)the bottom of the sea
                            G (320003@1)  A (x02220@1)  Di (xx0232@1)will teach you how to love me
                            G (320003@1)  A (x02220@1)  Dinto (xx0232@1)greatness i will lead you
                       G (320003@1)  A (x02220@1)  D'cause (xx0232@1)i'm a black mermaid
                       G (320003@1)  A (x02220@1)  Dnothing (xx0232@1)rarer you will find
                         G (320003@1)  A (x02220@1)  Di (xx0232@1)am here for you to love me
                          G (320003@1)  A (x02220@1)  Di've (xx0232@1)been here for all o' time
            G (320003@1)             A (x02220@1)               Dand (xx0232@1)i will wait for you to see me and to understand
        G (320003@1)            A (x02220@1)               Dthat (xx0232@1)a woman can restore the soul of any broken man
           G (320003@1)                A (x02220@1)              Dif (xx0232@1)you can look beyond the waves and just believe in me 
           G (320003@1)               A (x02220@1)                   Di (xx0232@1)am the lighthouse standing strong atop the rocks and sand
                      G (320003@1)  A (x02220@1)  D'cause (xx0232@1)i'm a black mermaid
                       G (320003@1)  A (x02220@1)  Dfrom (xx0232@1)the bottom of the sea
                          G (320003@1)  A (x02220@1)  Di (xx0232@1)will teach you how to love me
                        G (320003@1)  A (x02220@1)  Dinto (xx0232@1)greatness i will lead you
              G (320003@1)              A (x02220@1)              Dand (xx0232@1)i've spent most of my life deep down inside myself
            G (320003@1)                A (x02220@1)           Di've (xx0232@1)dreamt about the possibility of someone else
           G (320003@1)                A (x02220@1)                Dwho (xx0232@1)could see the things i've seen and steal away with me
          G (320003@1)                A (x02220@1)                Dinto (xx0232@1)the darkness we could fade because we know ourselves
                      G (320003@1)  A (x02220@1)  Dand (xx0232@1)i'm his black mermaid
                       G (320003@1)  A (x02220@1)  Dfrom (xx0232@1)the bottom of the sea
                          G (320003@1)  A (x02220@1)  Di (xx0232@1)will teach you how to love me
                           G (320003@1)  A (x02220@1)  Dinto (xx0232@1)greatness i will lead you
                    G (320003@1)  A (x02220@1)  Dyeah (xx0232@1)i'm a black mermaid 
                       G (320003@1)  A (x02220@1)  Dfrom (xx0232@1)the bottom of the sea
                         G (320003@1)  A (x02220@1)  Di (xx0232@1)will teach you how to love me
                         G (320003@1)  A (x02220@1)  Dinto (xx0232@1)greatness i will lead you
          G (320003@1)               A (x02220@1)            Dand (xx0232@1)i've spent most of my life deep down inside myself
          G (320003@1)                A (x02220@1)           Di've (xx0232@1)dreamt about the possibility of someone else
           G (320003@1)               A (x02220@1)            Dwho (xx0232@1)could see the things i've seen and steal away with me
           G (320003@1)               A (x02220@1)            Dinto (xx0232@1)the darkness we could fade because we LOVE ourselves
                     G (320003@1)  A (x02220@1)  D (xx0232@1)       
and i'm his black mermaid
                    G (320003@1)  A (x02220@1)  Dhe (xx0232@1)thinks i'm beautiful
                      G (320003@1)  A (x02220@1)  Dyeah (xx0232@1)i'm his black mermaid
                     G (320003@1)  A (x02220@1)  Dhe (xx0232@1)thinks i'm beautiful
            G (320003@1)  A (x02220@1)  Di (xx0232@1)am beautiful
G (320003@1)                       A(All (x02220@1)the dark horses and all the good men,
Dwon't (xx0232@1)you come put me back together again?)   repeatx4
            G (320003@1)  A (x02220@1)  Di (xx0232@1)am beautiful.

Contact me with questions, comments or corrections, please. Thanks! Hope this is good :D
~Kate