This fish may be one of the most colorful fish in the open Gulf of Mexico. It is azure blue to emerald green on its back, with cadmium yellow sides and a lighter belly. These bright colors are quickly lost when the fish dies after being boated. The large colorful dorsal fin extends almost the length of the back. Large mature males develop blunt, vertical heads. This fish is difficult to separate from its less common relative, the pompano dolphin. The only sure way to do so is to inspect the shape of the tooth patch on the tongue. In dolphin it is round; in pompano dolphin it is noticeably squarish in shape.

If ever the motto "Live Fast - Die Young" could be applied to a fish it would apply to the dolphin. It has an explosively fast growth rate. It may be the only fish for which scientists can measure their growth rate on a daily basis. In the Gulf of Mexico, dolphin grow at the rate of 5 inches per month, topping out at a maximum size of 42 - 5 feet in length in 2 years. Then they die! Scientists estimate that 100% of Gulf of Mexico dolphin die before they are 2 years old. Dolphin are eating machines. In the Gulf of Mexico and south Atlantic, they eat more triggerfish than anything else, followed by decapods (shrimp relatives), squid, jacks, and flying fish.

Dolphin begin spawning when they are almost 21 inches long, during their first year of life. In the Gulf, spawning occurs in the summer in high-salinity offshore waters at water temperatures of 75º F or higher. Particularly high numbers of larval (baby) dolphins have been found near the Mississippi River Delta. They spawn repeatedly during the season, laying 85 thousand to 12 million eggs per spawn, with larger fish producing more eggs.

More females than males are caught in the fishery. It seems that small fish of both sexes, and females of all sizes, spend more time around floating objects and seaweed rips, and are therefore easier to locate. Large males spend more time in open water traveling between female-dominated schools near floating cover. This makes females (and small dolphins) easier for fishermen to find and therefore catch.