Are the reactions of ordinary molecular hydrogen slow or rapid ? why ?

In nature reactions of ordinary molecular hydrogen are slow since it's  a diatomic molecule whose atoms are held together by very strong covalent bonds.The reaction rate of hydrogen varies depending on temperature and the properties of the reactants, for instance under high temperatures above 500°C hydrogen reacts vigorously and with fluorine it reacts explosively even under low temperatures

I’d have to say no because without oxygen in the water the fish would all be dead. so if you want to fish for dead fish, pick the ponds with the lowest oxygen concentrations.