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Trout Grader Bar Widths

Graders have been used in commercial trout farming for years. Separating smaller fish from larger fish can increase feeding efficiency, thereby decreasing production costs. Intensive grading may occur when selecting fish for processing if the market demands a consistent size.

The following chart can be used to build inexpensive graders for trout farming. The bars can be constructed from plastic or metal pipe with the frame of the grader made of wood. If plastic pipe is used, a stabilizing bar in the middle may be required to prevent the bars from bending and allowing larger fish to pass through.

Bar Width Fish Size Sample Count Fish Length in Inches
(inches) ozs grams (#/lb) C=.0004 C=.00045
3/16 .05 1.5 312 2.0 1.9
1/4 .10 2.8 160 2.5 2.4
3/8 .17 4.9 93.0 3.0 2.9
1/2 1.0 28.4 16.0 5.4 5.2
9/16 1.5 42.6 10.7 6.2 5.9
5/8 2.0 56.8 8.00 6.8 6.5
3/4 4.0 113.5 4.00 8.5 8.2
7/8 8.0 227.0 2.00 10.8 10.4
1 10 283.8 1.60 11.6 11.2
1 1/16 12 340.5 1.33 12.3 11.9
1 3/32 13 368.9 1.23 12.7 12.2
1 1/8 14 397.3 1.14 13.0 12.5
1 3/16 16 454.0 1.00 13.6 13.0
1 1/4 18 510.8 .89 14.1 13.6
1 3/8 24 681.0 .67 15.5 14.9
1 7/16 28 794.5 .57 16.4 15.7

Written By

Photo of John Dorner, IVJohn Dorner, IVArea Agent, Information Management (828) 290-9876 john_dorner@ncsu.eduMadison County, North Carolina
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