He and his sister once went on a fishing holiday on Catualla. Their refrigeration unit malfunctioned causing their catch to freeze into blocks of lumpy grey ice they called ichtysicles. Seven months later, in 2367, Tosh was killed in a cave-in whilst surveying a mine.
Tosh's death was a source of much distress for his sister, pain which was reignited when she relived her father telling her of the accident when she had a flashback caused by the Orb of Memory in 2376. (DS9 - Avatar novel: Book One)