This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Matsya (Hindu mythology)
Matsya is generally represented as a four-armed figure with the upper torso of a man and the lower of a fish. The upper torso has four hands, two of which carry the a conch-shell and a discus, while the other two are held in the Varada and Abhaya poses, signs of charity and fearlessness, respectively.
Matsya may also carry a variety of other weapons and symbols which are typical of Vishnu. Matsya is often depicted with two or three eyes, or from a side profile with only one eye visible as is typical of a fish. Matsya is commonly white in color. Sometimes his jaws are held agape in order to illustrate his ferocity.