I am going to call these Bonga fish, because they are the single most important fish for food in the country, and because a similar motif with confirmed Bonga appears on an earlier coin.
Mammy (or "Madam") Yoko was Queen of Kpaa Mende Seneghum (precursor to Sierra Leone) from 1878-1908.
This coin was issued one year only.
All coin images in Daniel's Coin Zoo are from my personal collection. I collect, research, and personally photograph every coin displayed on this site. PLEASE do not take my images without permission. If you would like to use any coin image you see, just ask me. Thank you.