I think you might be thinking of a hippocamp.
http://en.wikipedia.org/wiki/Hippocamp
Half a fish.
Like a mermaid, or merman?
8 ounces of fish = Half a pound =225g
It is 'Half an hour'. In English Grammar, any noun, prefixed by the indefinite article, that begins , with a,e,i,o,u & h uses 'AN'. e.g. An Horse, An House,
Miniature horse. Full grown, they're no bigger than a small pony. 86-97cm, so just about a meter.