Abstract: An apparatus for the grading of fish into various size categories, utilizing a series of panels with progressively smaller spaces between grading bars on the panels. The panels are attached to a panel box that may be raised or lowered within a holding vat. Water constantly flows through the holding vat, up through the panel box, and out over a spillway at the top front of the holding vat. By raising the panel box, the largest fish are forced out of the holding vat and down the spillway by the grading bars on the panels inside the panel box. Smaller fish swim through the grading bars on the panels with wider spaces between grading bars, and are not forced out of the holding vat until a lower panel with narrower spaces between grading bars is raised to the edge of the spillway. The constant flow of water up and toward the spillway causes the fish to instinctively swim downward and align themselves parallel to the grading bars and keeps the fish oxygenated during the grading process.