Platycephalus sp.

INTRODUCTION

The bartail flathead (Platycephalus indicus), also known as the Indian flathead, gobi or Indo-Pacific flathead, is a species of largely marine ray-finned fish belonging to the family Platycephalidae, the flatheads. This species is found in the Indian Ocean and the Western Pacific Ocean, and has invaded the eastern Mediterranean Sea.

DESCRIPTION

Physical Features:

• The bartail flathead has a flattened head.

• It's generally smooth but has some low ridges on certain parts of its head: parieto-occipital, scapular, and preopercular ridges. These ridges aren't sharp or serrated.

• There's a short, blunt spine in front of its eye.

• The preoperculum (a bone in the gill cover) ends in two strong, slightly upturned spines.

• It has teeth similar to canine teeth on the vomer (the bone in the roof of the mouth), and there's a single clear row of similar teeth on the palatine (another bone in the roof of the mouth). The jaws have wide bands of small, villiform teeth (like tiny brushes).

Fins:

• The first dorsal fin has a short first spine that's separate from the rest of the fin, followed by 7-9 additional spines.

• The second dorsal fin and anal fin both have 13 soft rays (soft, flexible parts of the fin).

• The rear edges of the second dorsal fin and anal fin have deep cuts in the tissue between the rays.

Coloration:

• The overall color is brownish, with 8 or 9 faint, blurry bands across its back.

• The top of its head has small, roundish spots with pale rings around them.

• The lower part of its body is yellowish.

• Its fins (except for the tail fin) have rows of faint spots on the fin rays.

• The tail fin has a black band running lengthwise through the middle, with two diagonal black bands above and below it.

Size:

• It can reach a maximum length of 100 cm (39 in), although it's more common to find them around 60 cm (24 in).

• The maximum published weight is 3.5 kg.

HABITAT

The bartail flathead fish lives in waters ranging from 20 to 200 meters deep, typically over sandy or muddy bottoms. They're commonly found near reefs or seagrass beds. Interestingly, young bartail flatheads have been observed venturing into the freshwater areas of rivers.

REPRODUCTION

• Sexual maturity in this species is reached at varying ages, contingent upon factors like geographical location, habitat conditions, and individual growth rates. Typically, sexual maturity is achieved when individuals attain a certain size and age threshold, which can differ among populations.

• Spawning behavior in Platycephalus indicus is characterized by seasonal patterns, with peak spawning activity typically occurring during warmer months. Environmental cues such as water temperature, photoperiod, and lunar phases often trigger spawning events. During this period, individuals may migrate to specific spawning grounds or aggregation sites conducive to reproduction.

• Reproduction in Platycephalus indicus primarily involves external fertilization. Females release eggs into the water column, where they are fertilized by the sperm released by males. This process usually transpires near spawning grounds or over suitable substrate where eggs can adhere and develop. Subsequently, the development of fertilized eggs progresses through various stages, including cleavage, gastrulation, and organogenesis. Factors such as water temperature, oxygen levels, and predation pressure can influence the rate of egg development.

• Upon hatching, the larvae of Platycephalus indicus enter the water column as planktonic entities, drifting with ocean currents. During this larval stage, significant morphological and physiological changes occur as larvae develop structures necessary for swimming, feeding, and survival. Eventually, as larvae continue to mature, they undergo metamorphosis and settle onto the substrate. Settlement may transpire in various habitats, including seagrass beds, mangrove areas, and rocky reefs. Juvenile flatheads exhibit behaviors and feeding habits distinct from adults as they adapt to their new benthic environment.

• Following settlement, juveniles of Platycephalus indicus experience rapid growth, feeding on small prey items and evading predators. Growth rates may fluctuate based on factors such as food availability, habitat quality, and interspecies competition. As individuals grow and mature, they transition into the adult stage, eventually attaining reproductive maturity and participating in the spawning cycle. The reproductive success of Platycephalus indicus hinges on various factors, including spawning frequency, egg production, and the survival rates of larvae and juveniles. Environmental variables such as temperature fluctuations, habitat degradation, and anthropogenic impacts can significantly influence reproductive output and overall population dynamics.

BEHAVIOR AND DIET

• Indian flatheads are primarily nocturnal predators, often remaining buried in sand or mud during the day and becoming active at night.

• They are ambush predators, lying in wait for smaller fish and crustaceans to pass by before striking.

• Their diet consists mainly of small fish, crustaceans, cephalopods, and other benthic invertebrates.

COMMERCIAL IMPORTANCE

• Indian flatheads are commercially important in some regions, particularly in the Indo-Pacific, where they are caught for food.

• They are often caught using bottom trawls, gillnets, and handlines.

• Due to their relatively large size and mild-tasting flesh, they are valued by commercial and recreational fishers alike.