John Gill, on Gen 1:22

“And he blessed them, saying: Increase and multiply, and fill the waters of the sea: and let the birds be multiplied upon the earth.”

“And God blessed them,.... With a power to procreate their kind, and continue their species, as it is interpreted in the next clause, saying, be fruitful, and multiply, and fill the waters in the seas: and these creatures do multiply exceedingly, and vast quantities there are of them in the mighty waters, though the consumption of some sorts of them is very great. Our English word "fish" is derived from the Hebrew word "fush", which signifies to multiply and increase: and let fowl multiply in the earth; as they did, and continue to do to this day.”

Imported from an open dataset — not yet checked against the printed edition.