It’s a catfish. Who is also a cat. A catfish cat! Who is also a merfolk. So it’s a catfish mercat! But not a meerkat! But it’s definitely a catfolk!  
Also counts as a cuckoo since it’s based on the cuckoo catfish.  
Technically also a taur.  
So it’s a cuckoo catfish merfolk taur!  
*rolls over*
*brb high on catnip*
 
Anyway, the knife is for anybody who might want to try fertilizing her eggs without her consent. Obviously.  
Neither pair of gills makes anatomical sense, nor do the barbels which should be forward-pointing and shaped differently, but then merfolk in general don’t make much anatomical sense and I liked the idea of gills being very visible on her whereas most merfolk artwork just omits them.
 
Plants: a species of Coratophyllum on the right and a fictional giant Potamogeton on the left.
 
The girl is supposed to be relatively small, about 1.2 meter long from muzzle to tail tips. The location is a fantasy version of Lake Tanganyika which hosts the actual cuckoo catfish (Synodontis genus, visible in the lower left area) as well as the other fish species seen in the drawing (Cyphotilapia frontosa on the right, Tropheus ikola top left).