Animal Pictures: Spiny Eels and Gar Fish

Spiny Eels

Fire eel

The fire eel (Mastacembelus erythrotaenia) is a large freshwater fish found in Cambodia, Indonesia, Laos, Malaysia, Thailand, and Vietnam.

The fire eel is not a true eel, but an extremely elongated fish with a distinctive pointed snout and underslung mouth. It is part of a group of fishes called spiny eels that also includes tire track and peacock eels. The group gets its common name from the many small dorsal spines that precede the dorsal fin. The body is laterally compressed, particularly the rear third, where it flattens as it joins the caudal fin and forms an extended tail. The fire eel's base coloring is dark brown/grey, while the belly is generally a lighter shade of the same color. Several bright red lateral stripes and spots mark the body, and vary in intensity depending on the age and condition of the individual. Usually the markings are yellow/amber in juvenile fish, changing to a deep red in larger ones. Often the anal, pectoral, and dorsal fins have a red edging.

The fire eel can grow to a considerable size in the wild with specimens often exceeding 1.2 meters (3.9 ft) in length. However, due to limiting factors in the captive environment they usually reach a maximum of around 55 centimeters (22 in), even in very large aquaria.

Fire eel

Spotfinned spiny eel

Macrognathus siamensis is a tropical fish belonging to the Mastacembelidae family. As an aquarium fish it is known with the common name peacock eel or peacock spiny eel.

Macrognathus siamensis has been recorded to reach a maximum length of 30 centimetres (12 in). M. siamensis is a freshwater species, generally found at the bottoms of bodies of water. It is found in the rivers of Southeast Asia, including the Mekong, Chao Phraya, and Mae Klong. During the day, Macrognathus siamensis buries itself in the river bottom, coming out at night to feed on insects, crustaceans, and worms.

Spotfinned spiny eel

Tire track eel

The tire track eel (Mastacembelus armatus) is a species of ray-finned, spiny eels belonging to the genus Mastacembelus (Scopoli, 1777) of the family Mastacembelidae, and is native to the riverine fauna of India, Pakistan, Sumatra, Sri Lanka, Thailand, Viet Nam, Indonesia and other parts of South East Asia. The species was named Mastacembelus armatus by Lacepède in 1800. Other common names for this popular aquarium species are zigzag eel, spiny eel, leopard spiny eel and white-spotted spiny eel. This species is not only a popular aquarium fish but also as a food fish in its country of origin.

Mastacembelus armatus is a large elongated fish that has a snake-like body without pelvic fins. Its anal and dorsal fins are elongated and are connected to the caudal fin. The dorsal fin is preceded by numerous spines. The back is dark beige in color while the head is silver-beige. The body’s color is dull brown and the belly is a lighter shade of brown. The body may also be marked with brown circular patterns. The body also have one to three darker longitudinal zigzag lines that connect to form a distinct reticulated pattern that is restricted to the dorsal two-thirds of the body. The eyes have brown stripes running laterally through them.

Mastacembelus armatus can reach up to 36" (91 cm) in its natural habitat but does not usually exceed 20" (51 cm) in captivity.

Despite its eel-like appearance, Mastacembelus armatus is not considered a true eel.

Tire track eel

Gar Fish

Spotted Gar

The spotted gar (Lepisosteus oculatus) is a primitive freshwater fish of the family Lepisosteidae, native to North America from the Lake Erie and southern Lake Michigan drainages south through the Mississippi River basin to Gulf Slope drainages, from lower Apalachicola River in Florida to Nueces River in Texas, USA. It has a profusion of dark spots on its body, head, and fins. Spotted gar are long and have an elongated mouth with many teeth used to eat other fish and crustaceans. They grow to 0.61–0.91 metres (2–3 ft) in length and weigh 1.8–2.7 kilograms (4–6 lb) on average, making it the smallest of the gars. The name Lepisosteus is Greek for "bony scale". Habitat for spotted gar is clear pools of shallow water in creeks, rivers, and lakes.

The spotted gar Lepisosteus oculatus is a part of the gar family (Lepisosteidae). They are notable for being one of the few extant fish species with ganoid scales. They have been known to hybridize with (and look similar to) Florida gar. It occurs in quiet, clear pools and backwaters of lowland creeks, small to large rivers, oxbow lakes, swamps, and sloughs. It occasionally enters brackish waters. The fish is a voracious predator, feeding on various kinds of fishes and crustaceans. The lifespan for L. oculatus varies between males and females. The maximum lifespan for a gar is 18 years. Males mature at the age of two or three, whereas females mature at three or four years old. Females on average are known to be larger and live longer than the males. Females also have less annual mortality rates.

Spotted Gar

Florida Gar

The Florida gar (Lepisosteus platyrhincus) is a species of gar found in the USA from the Savannah River and Ochlockonee River watersheds of Georgia and throughout peninsular Florida. Florida gars can reach a length of over 3 ft (91 cm). The young feed on zooplankton and insect larvae, as well as small fish. Adults mainly eat fish, shrimp, and crayfish. Although edible, they are not popular as food. The roe is highly toxic to many animals, including humans and birds. Gar are mentioned in the John Anderson song "Seminole Wind".

Florida Gar

Longnose Gar

The longnose gar (Lepisosteus osseus) is a primitive ray-finned fish of the gar family. It is also known as the needlenose gar. L. osseus is found along the east coast of North and Central America in freshwater lakes and as far west as Kansas and Texas and southern New Mexico. The gar have been present in North America for about 100 million years.

Longnose Gar

Shortnose Gar

The shortnose gar (Lepisosteus platostomus) is a primitive freshwater fish of the family Lepisosteidae. It is native to the United States where its range includes the Mississippi and Missouri River basins, ranging from Montana to the west and the Ohio River to the east, southwards to the Gulf Coast. It inhabits calm waters in large rivers and their backwaters, as well as oxbow lakes and large pools. It is a long, slender fish, brown or olive green above and whitish below. It typically grows to about 60 cm (24 in) and is armoured by rows of interlocking, rhomboidal ganoid scales.

The shortnose gar is an ambush predator, feeding mostly on fish, but also consuming crustaceans, insects and other invertebrates. Breeding takes place in spring when females, often accompanied by several males, attach their eggs to clumps of submerged vegetation. The eggs, which are toxic to man, hatch after a week or so. After consuming their yolk sac, the young fish feed on insect larvae and small crustaceans, maturing at an age of about three years.

Shortnose Gar

Alligator Gar

Alligator gar (Atractosteus spatula) are ray-finned euryhaline fishes related to bowfin in the infraclass Holostei (ho'-las-te-i). The fossil record traces the existence of alligator gars back to the Early Cretaceous over a hundred million years ago. They are the largest in the gar family, and among the largest freshwater fishes in North America. Gars are often referred to as "primitive fishes", or "living fossils" because they have retained some morphological characters of their earliest ancestors, such as a spiral valve intestine which is also common to the digestive system of sharks, and they can breathe both air and water. Their common name was derived from their resemblance to American alligators, particularly their broad snout and long sharp teeth. Anecdotal evidence included in scientific reports suggest that alligator gars can grow up to 10 ft (3.0 m) in length and weigh as much as 300 lb (140 kg); however in 2011 the largest alligator gar ever caught and officially recorded was 8 ft 5 1⁄4 in (2.572 m) long, weighed 327 lb (148 kg), and was 47 in (120 cm) around the girth. Their bodies are torpedo shaped, usually brown or olive fading to a lighter gray or yellow ventral surface. They do not have scales like other fish, rather they are armored for protection against predation with hard, enamel-like, jagged diamond-shaped ganoid scales that are nearly impenetrable. Unlike other gar species, mature alligator gars have a dual row of large sharp teeth in the upper jaw which they use for impaling and holding prey. They are stalking, ambush predators that are primarily piscivores, but will also ambush and eat water fowl and small mammals that may be floating on the surface.

Alligator gars have been extirpated from much of their historic range through habitat destruction, indiscriminate culling, and unrestricted harvests. Populations are now located primarily in the southern portions of the United States extending into Mexico. They are considered euryhaline because they can adapt to varying salinities ranging from freshwater lakes and swamps to brackish marshes, estuaries, and bays along the Gulf of Mexico.

For nearly a half-century, alligator gars were considered "trash fish", or a "nuisance species" that were detrimental to sport fisheries, and therefore targeted for elimination by state and federal authorities in the United States, but the last ten years has seen a greater emphasis placed on the importance of alligator gars to the ecosystems they inhabit. As a result, they were afforded protection by restricted licensing. They are also protected under the Lacey Act which makes it illegal to transport fish in interstate commerce when in violation of state law or regulation. Several state and federal resource agencies are monitoring populations in the wild, and have initiated outreach programs to educate the public. Alligator gars are being cultured in ponds, pools, raceways and tanks by federal hatcheries for mitigation stocking, by universities for research purposes, and in Mexico for consumption.

Alligator Gar

Cuban Gar

Tropical Gar