The growth of the fish population is not occurring because oil is good for fish. Rather, it is occurring because fishing is bad for fish. When fishing was banned for months during the spill, the Gulf of Mexico experienced an unprecedented marine renaissance that overwhelmed any negative environmental consequences the oil may have had.
Oil is being measured in parts per billion - meaning the water is safe enough to drink - and very little has been found on the ocean bottom. Much of it has been eaten by bacteria native to the Gulf’s oil seeps, and . . . other microscopic creatures including flagellates and ciliates ate the bacteria, and in turn provided food for plankton.