Definition of "fishling"

[…] said an older woman, bending over her, "hush, little fishling! Ichuk, my son, is dead, but we will get thee another man."

1898, The Yale literary magazine

My fingers moved subtly, and now Fiacha was a tiny raven no bigger than a bee, a little speck of darkness that spun out of the fixing charm as easily as a fishling escapes the herring net, […]

2008, Juliet Marillier, Child of the Prophecy