It is difficult for underwater robots to detect targets in complex underwater environments or when the targets have protective colors only by acquiring images with conventional optical cameras, and underwater target detection by hyperspectral techniques can improve this situation. Since it is difficult to meet the requirements of underwater robot for underwater target detection by directly applying traditional hyperspectral detection methods, this paper proposes a hyperspectral target detection method based on Optimal Neighborhood Reconstruction Index Factor (ONRIF), which is based on the idea of linear reconstruction for neighborhood finding, selecting a combination of bands with high information content and low band correlation, and using the band fusion map for target detection. The results show that compared with the direct detection of the original hyperspectral images of underwater seafood, the method substantially reduces the detection time and the degree of data redundancy while ensuring the detection effect. This paper also proposes a single-band fast acquisition detection method for similar targets in the same environment, which greatly improves the speed of data acquisition and can meet the needs of underwater robots for seafood detection.