Determination of morphometric parameters in the Mexican mojarra, Cichlasoma urophthalmus (Günther), for the design and construction of box graders

Abstract. The morphometric relationships, standard length-weight, standard length-width and weight-width for Cichlasoma urophthalmus (Günther) in the weight range 0.78-262g were: log₁₀ weight =−4.35 + 2.95 × (log₁₀ standard length); log₁₀ width =−0.73 + 0 99 × (log₁₀ Standard length) and log₁₀ width = 0.74 + 0.33 × (log₁₀, weight). Two box graders were designed and tested based on these data. The operation efficiency (expressed as a percentage of the sample used to test it) was 96.1 % and 95% for the two graders. Results indicated a tendency to undergrading (small fish detained by the bars) by the first grader and overgrading (large fish going between the bars) by the second, the latter as a result of the major variability in the body shape from fish as they grow. The results are satisfactory, and larger graders for commercial use could be constructed based on these relationships.