What is Hind Fish?

Among the different marine fish species consumed by humans, hind fish is a very popular one. There are several species of hinds present in the ecosystem. All these species are edible and are considered to be prized capture. They all belong to the sea bass family Serranidae. Their order is for Perciformes. All hind species belong to the genus Epinephelus. However, the genus also includes several species of groupers. 

Geographical Distribution of Hind Fishes

Hind animals are mostly found in the Gulf of Mexico along the coast of North America. They are also found in the Atlantic ocean. The only exception amongst Hind fish that does not exist in this region is the red hind (E. guttatus). They are mostly found between Brazil and the Carolinas. 

Similarly, the rock hind (E. adscensionis) is mostly found in the region extending from the West Indies to New England. They can reach up to a length of 24 inches (61 cm). The speckled hind (E. drummondhayi) is somewhat smaller, mostly growing to a length of 19 inches (46 cm). They are mostly found along the southeastern coast of the United States.

General Description of Hind Fish

There are different types of hind fishes in the world. All the variants differ in their body structure, length, and colour. To know about hind fishes, it is important to know about these kinds separately. Let us study some of them.

1. Red Hind fishes 

A. The Body Structure of Red Hind Fishes

For example, the red hind has a compressed, robust body. The deepest part is near the base of the dorsal fin. The standard length of red hind fish is around 2.7 to 3.1 times the depth where it is found in water. Along the margins of the gills, there are three flat spines. The preopercle of the fishes has a characteristic fine serrated margin that protrudes out near its lower edge. 

The dorsal and the anal fins also differ from each other. The dorsal fin has around 15-16 soft rays and 11 spines. However, the anal fin has 8 soft rays and 3 spines. The tail is slightly convex. 

The red hinds are light brown to greenish-grey in colour in the upper parts of the body. However, the colour fades to white in the lower region. They also have several brown or orange-red spots that cover their body, head, and even fins. On the flanks of the body, you will find distinct oblique bars (five in number). They can grow to a maximum length of 30 inches (76 cm). However, the general length of the body is 16 inches (40 cm). The maximum weight of a red hind fish recorded till now is 49 lbs (22 kilograms).

B. Habitat Description of Red Hind Fishes

Red hind fishes mostly live in rocky bottoms and coral reefs. The females prefer to stay close to the bottom. The males take up the responsibility to patrol the area. This patrolling is required to defend the area from other males. The ranges mostly comprise overlapping regions of one to five males.

C. Food Habits of Red Hind Fishes

Red hinds mainly feed on crabs. Mantis shrimp also forms a major percentage of their diet. They also feed on other fishes like Boga, Thalassoma bifasciatum, Bluehead Wrasse, goatfishes, small morays, etc. They can also eat small octopuses. 

D. Hermaphrodite Nature and Breeding Habits of Red Hind Fishes

Red hinds exhibit protogynous hermaphroditism. The females can change into males at one stage of their life cycle. However, the trigger for such a change is still unknown. They also show distinctive spawning behaviour. For example, in Puerto Rico, they gather in or near familiar spawning grounds along certain sections of the insular shelf. Their breeding period remains for one or two weeks, and they are associated with the lunar cycles in January and February.

An experiment in 1992 showed a tagged Red Hind fish traveled a distance of more than 10 miles and a depth of more than 600 feet to reach the spawning site. The juveniles hardly come out of their patches. Therefore, not much is known about the early life stages of red hind fishes. Most adult red hind fish can live up to 10-11 years.

2. Coral Hind Fishes

A. The Body Structure of Coral Hind Fishes

The body structure of coral hind fishes is robust and oblong. They have an interorbital area that is flat to slightly convex. Their preopercle is rounded. The size of the posterior and the anterior nostrils is subequal. The adult coral hind fish has a rounded margin on their dorsal fins. Generally, the pelvic fin does not extend till the anal region. The caudal and anal fin are also rounded. The pectoral fins are rounded and show a definite symmetry.

B. The Colouration of the Coral Hind Fish

Most coral hind fishes are reddish-brown or orange-red in colour. They have a darker hue on the posterior regions of the body. They also have characteristics of bright blue spots with darker edges. These spots are all over their body, head, and median fins.

The soft regions of the anal and dorsal fin have a narrow blue margin supplemented with a blackish submarginal line. Similar margins are also found on the distal margin of the caudal fin. The pectoral fins also show distinct orange-yellow coloration in the distal regions. The pelvic fins are also orange-red in color. They have a distinct grayish dark blue margin in the distal region. The juvenile coral hinds are lighter, more yellowish in color, and have fewer blue spots than adults.

Due to such colorations, coral hinds are often confused with sixblotch hind fish (C. sexmaculatus). However, there are distinct differences in their coloration. The sixblotch hind fish has darker blotches on their dorsal surface as well. They even have blue lines emanating from the eyes. Coral hind fishes do not have such colors.

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C. The Dentition of Coral Hind Fishes

Like other hind fishes, coral hinds feed on smaller organisms. They have small canines in the front. They also have teeth in the palatines. These teeth are so designed to enable them to have the best bite and capture small fishes and organisms.

D. General Age, Size, and Growth of Coral Hind Fishes

The maximum length of the coral hind reported to date is 45 cm (18 inches). The coral hind fish reach sexual maturity when they reach a length of 26 cm (10 inches).

E. Food Habits of Coral Hind Fishes

Coral hind fishes mainly prey in the early morning or during the afternoon. Their common preys include small fishes. The most common of them is Pseudanthias squamipinnis. This fish makes up around 80% of their food. They also feed on Apogon spp., Anthias spp., and Canthigaster margaritata.

Coral hind fish also feed on crustaceans. They mainly feed on shrimps and crabs. They are ambush predators who hind in the corals. They also prefer to spend maximum time on the bottom, waiting for the prey to come into their reach. Once they spot prey, they prey on them with their strong teeth. 

F. The Reproductive Process of the Coral Hind Fish

The major characteristic of the coral hind fish reproduction is their interspecific haremic groups. Such groups consist of two to twelve females with only one dominant male. Coral hind fishes occupy huge territories. Some groups can occupy around 475-2000 square meters. Each territory is further subdivided into secondary territories. Each of these secondary territories is inhabited by individual female coral hind fish.

The males generally patrol the area inhabited by the territory. They do so to keep other males or other fishes from encroaching into their territory. The females generally occupy the central region. However, visiting females are also included in the territory. The male and female coral hind fishes often swim in antiparallel directions. 

G. Predators of Coral Hind Fish

Although coral hind fish feed on smaller fishes and crustaceans, they also face the risk of predation. Many fishes larger than the coral hind fish are potential predators. They also face the risk of predation by larger marine mammals. Their hiding behavior is mainly attributed to being under the constant pressure of predation. However, they also do so to ambush and hunt small fishes.

Hind Fish For Human Consumption

Humans consume several varieties of hind fish. These fishes are considered to be a prized catch for fishermen. This is because they generally do not live in large groups. They only show congregational behavior only when they show habitat preferences.

FAQs on Hind Fish

1. What is the Coloration Pattern Demonstrated By the Coral Hind Fish?

Ans: The coral hind fish is one of the most brightly colored hind fishes. They are mostly orange-red or reddish-brown in color. The color tends to be darker on the posterior regions of the body. They have distinctive bright blue spots with dark edges covering their body. They are also found on the head and the median fins. 

The softer regions of the dorsal fin and the anal fin exhibit a narrow blue margin. It also has a black submarginal line. Such margins are also found on the distal margin of the caudal fin. The distal regions of the pectoral fins are orange-yellow in color. The pelvic fins are orange-red. The distal region of the pelvic fin has distinct grayish dark margins. The juvenile corals are more yellowish and have lesser blue spots than adults.

2. What are the Reproductive Processes and Territorial Structures of the Coral Hind Fishes?

Ans: Interspecific harem is the major characteristic of the coral hind fish population. The characteristic of this group structure is one male being partnered with multiple females. In the coral hind fish territory, a single male fish stays with two to twelve females. They also occupy huge territories spanning around 475-2000 square meters. This big territory is further divided into several secondary territories. A single female coral hind fish occupies a single secondary territory.

The males show patrolling behavior in this territory. Such behavior is mainly targeted towards preventing other males or predators from entering the territory. The females occupy the central space. The male and the female coral hind fishes mostly exhibit antiparallel swimming behavior. This swimming pattern can be a form of mating behavior between the two genders of coral hind fishes. 

3.  What are the Hermaphroditic Properties and Reproductive Nature of Red Hind Fishes?

Ans: Red hind fish has the unique property of protogynous hermaphroditism. In this process, the female individuals can change into males at any point in their life cycle. However, the trigger to change the gender of the individual is still unknown. 

The red hind fish also show distinctive spawning behavior.  They show unique preferences for their spawning ground. For example, the red hind fish found in Puerto Rico often gather around familiar spawning grounds along defined sections of the Insular shelf. They have around one to two weeks of breeding periods. Such breeding periods are often associated with the lunar cycles in the months of January and February.

An experiment was conducted in 1992 to understand the spawning preferences of the Red Hind fish. A fish was tagged and monitored for such behavior. The fish traveled more than ten miles in length and 600 feet in depth to reach the spawning site. 

4. What is the Geographical Distribution of the Hind Fishes?

Ans: There are several varieties of Hind fishes. Most of them share a common habitat, although some of them have distinct habitats of their own. They are mostly found along the North American coast in the Gulf of Mexico. Some Hind fishes are also found in the Atlantic ocean. However, the red hind fish has a separate geographical distribution. They are mostly found in the Carolinas and Brazil. The rock hinds are also an exception to the group. They are found on a stretch from the West Indies to New England. These fishes can grow up to a length of 24 inches. The speckled hind is smaller in length (around 19 inches) and is mostly found along the southeastern coast of the United States.