What does ギョグ mean?


In my dictionaries and on the Internet, the only meaning I found for ギョグ was
"fishing gear", but in the context of the text I have been translating it does
not make sense. The context is: two monsters and a boy fell to the ground.

> ガ ガア!?
>
> Thud, Thuud!!
>
> ふっ!
>
> Shoom!
>
> ギョグ!?
>
> Fishing gear!?




It, as well as ガア, shoud be just a screech of that monster. ギョグ is not common,
but there is no rule on how imaginary monsters should cry.

