Fish don't breath water, they breathe dissovled oxygen that is in the water. Because pure oxygen is quite flammable, and pure oxygen is dissolved in water, why isn't water flammable? I'm sorry this question is so short and stupid looking but there isn't much to it. Thanks.
There are no "stupid" questions. Oxygen is a "Henery's Law" gas which means it is sparingly soluble in water. For example at 20 deg C and 1 atm pressure you can only dissolve 9.17 lb O2per one million pounds of water. The O2 molecules are moving around in the liquid and are too dilute to be ignited. Any energy, such as a torch, is totally absorbed by the H2O.