Vaseline, Good for What Ails You
Hi Steven,
I have used petroleum jelly for decades with no ill affects. :gw
It is not soluble in water and as long as the water temperature does not exceed 45 C (113 F) there should be no film, oily or otherwise.
If any gets into the aquarium, it is just a little glob of stuff, I have not seen any flora or fauna harmed.
Petroleum jelly is a mixture of hydrocarbons, originally derived from a byproduct of oil drilling (rod wax, I think

).
Biollante