“Fishpools” is generally considered a mistaken translation in the cited passages. The Hebrew references ordinary pools or, in Isaiah 19:10, laborers and their work rather than ponds for fish.
Definition
“Fishpools” is an older translation that is considered incorrect in the cited passages. The Hebrew in Song of Solomon 7:4 means simply “pools,” while the wording in Isaiah 19:10 concerns hired workers and their labor rather than ponds used for fish.
Biblical Usage
The term occurs in older renderings of Song of Solomon 7:4 and Isaiah 19:10. The Revised Version removes “fish,” reading “pools” in the first passage and “all they that work for hire shall be grieved in soul” in the second.
Historical Bible Dictionaries
International Standard Bible Encyclopedia (ISBE)
<p>fish'-pools:</p><p>This is a mistranslation. The Hebrew berekhoth (So 7:4) simply means "pools" (Revised Version); "fish" is quite unwarrantably introduced in the King James Version. In Isa 19:10, again, instead of "all that make sluices and ponds for fish" (the King James Version), we should certainly read, with the Revised Version (British and American), "All they that work for hire shall be grieved in soul."</p>