Home >> Science & Nature >> Nature

What Is the Difference Between a Rockfish & a Grouper?

Rockfish, of the scorpaenidae species, is classified according to color, such as red or black or banded, and within these, weak or strong head-spined. Groupers are members of the serranidae family of sea basses. Alternate names can sometimes interchange the two species, for example in the case of yellowfin grouper, which is also called princess rockfish or red rockfish. Black groupers are called black rockfish, and the Boccaccio rockfish is also called the salmon grouper.

Physical Characteristics
- The rockfish can grow to up to 41 inches, but the adult rockfish generally is 20 inches long. It has spiny venomous projections on the top of its body, as well as pelvic fins placed forward near the pectoral fins. GoFishn says that differentiating among different rockfish species can be difficult, and they are not marketed separately. The black grouper averages 2 to 3 feet in length but can be 4 feet long and weigh 100 pounds. This grouper has black-tipped fins and box-like patterns on its body. Yellowfin grouper undergoes two color phases, one similar to the black grouper, and the other is bright red; it maintains yellow-tipped pectoral fins throughout these stages.
Habitat
- Rockfish live in either the rocky shallow waters near the shore of the continental shelf or along the edge of the continental shelf in deeper waters. They are found in the Pacific Ocean, Alaska's coasts and up to the Bering Sea. Black grouper may be found as far north as Massachusetts and as far south as southern Brazil, but they are common in the Florida Keys and the Bahamas. Adult yellowfin grouper are found in coral reefs and mud bottoms of the Gulf of Mexico.
Behavior
- Rockfish form schools in open water above reefs, whereas the grouper has solitary habits amid coral reefs. Rockfish give birth to live young after internal fertilization. They copulate in the fall, sometimes storing the sperm before fertilization takes place. After holding onto the embryos for about a month, the female rockfish gives birth in the winter, spring or summer, depending on the northerly or southern geography of the population. Certain species such as the yellowtail rockfish prefer specific areas and return after relocation. Grouper spawn from March through July, laying both eggs and sperm that unite by chance. Larvae hatch from the eggs and drift before becoming juveniles. Hermaphroditic by nature, groupers transition from female to male as they mature.
Feeding
- Young rockfish consume plankton and fish eggs, while older rockfish eat other fish such as herring, as well as crustaceans. Yellowfin grouper eat the fish and squid that occupy coral reefs. Young grouper mainly eat crustaceans.

Nature