According to the log books of a northern British Columbia fishing lodge, 3,474 steelhead trout were caught and released on the Babine River during 2010-2014. The histogram below shows their distribution of weights.
After having lived in the ocean, many are returning to the river to spawn for the first time ("1-salt"). Unlike salmon, they may go back to the ocean, gain weight, and, a few years later, return to spawn for a second time ("2-salt).
Fish biologists might model this with a best-fit lognormal distribution (green dots), which cannot capture the bimodal nature of this population. In contrast, as the number of metalog terms approaches ten, its bimodality clearly emerges.