Claim: In the Ancient Hawaiian aquaculture, fishponds were located next to the mouth of a stream and have porous lava walls.
Evidence: Fishponds were located next to the mouth of a stream, so by opening a sluice gate the pondkeeper provided the fish with water rich in nutrients that had passed through inland, terraced pondfields and returned to the stream. The porous lava walls let in seawater (or sometimes fresh or brackish water, as in the case of the "Menehune" fishpond near LÄ«huÊ»e, KauaÊ»i), but prevent the fish from escaping. The Hawaiian fishpond was primarily a grazing area in which the fishpond keeper cultivated algae; much in the way a cattle rancher cultivates grass for his cattle.