Have you ever heard of water quality? Water Quatlity is all the stuff thats in the water and water quality jobs is when you test the water to see if it`s polluted or bad for fish. My water quality job is Temp.(temperture) like if it`s too hot the eggs in the water is not gonna hach and if it`s too cold the eggs will freeze. Ether way the egg would die. Also fish need a different Temp. because there cold blooded(that means there body temperture changes to the same temp. to the habitat.) most fish like salmon will want cold water. And because of global warming the temperture of the water is riseing not just the land. Remember 75% of the earth is water and 1% is drinkable and use for everyday chores. So please take care of our planets water and please don`t drink the water if it`s not clean trust me.