What is a Mooneye?

The mooneye is a silvery freshwater fish from North America. The shimmery creature is from the Hiodontidae family. This ray-finned fish gets its name from its large, round metallic eyes. Mooneye fish, commonly referred to as toothed herring, are not considered a valued source of food.

Several different types of fish are known as mooneye fish. These clupeoid fishes are considered primitive, with thin, nearly flat bodies. Mooneyes have prominently forked tails and very sharp teeth. These teeth are arranged on the fish's tongue as well as on the roof of its mouth.

Bellies of mooneye fish feature smooth scales. A small flap known as a pelvic auxiliary process can be found directly above the fish's pelvic fin. The fish's appearance is considered to be similar to that of the herring, providing it with its toothed herring nickname.

These fish are small, growing only up to 12 inches (31 cm) in length and an average of 1 pound (2.2 kg) in weight. Some larger mooneyes may measure up to 19 inches (48 cm) in length, and weigh up to 3 pounds (6.6 kg). Mooneye fish are carnivorous. Their diets consist of several different types of small organisms, such as shrimp, mollusks, insects, and other small fish.

Mooneye fish are a threatened group of animals. Their numbers continue to decline throughout their various habitats. One cause of their reduced population size is thought to be attributed to the siltation of water where the fish are found. Other causes of their dwindling numbers remain unknown.

Two species of the family, Hiodon tergisus, and Hiodon alosoides, remain alive and can be found widely across North America. The mooneye's habitat ranges from southern Canada to the Mississippi River basin. It prefers clear rivers, such as those found in lakes and ponds. Three of the species, Hiodon consteniorum, Hiodon rosei, and Hiodon woodruffi, are extinct.

Hiodon alosoides is also known as the goldeneye fish. While the Hiodon tergisus has a dorsal fin that begins before its anal fin, the goldeneye's dorsal fin is aligned with its anal fin. In contrast to the Hiodon tergisus, the Hiodon alosoides features golden irises rather than silver.

Eggs laid by these fish are similar in appearance and consistency to frogs' eggs. Mooneye fish typically lay their eggs over rocks from March to May. Spawning occurs in the spring. A single female fish can be expected to lay 10,000 to 20,000 eggs.

The Mooneye fish, scientifically known as Hiodon tergisus, is a freshwater species native to North America. It thrives in clear rivers and lakes, predominantly in the Mississippi River basin and the Great Lakes region. Mooneyes prefer habitats with slow-moving waters and are often found in areas with abundant aquatic vegetation.

Mooneye fish are identifiable by their large, silvery eyes which give them their name. They have a thin, deep body, resembling that of a shad, and a forked tail. Their scales are silvery and reflective, and they typically grow to about 12 to 15 inches in length, making them easily distinguishable from other freshwater species.

Mooneye fish are opportunistic feeders with a diet consisting mainly of insects, both aquatic and terrestrial. They also consume small fish and zooplankton. Their large eyes are an adaptation for feeding during low light conditions, such as dawn and dusk, when they can take advantage of insect activity on the water's surface.

While not traditionally targeted by sport fishers, the Mooneye can provide an enjoyable challenge due to its keen eyesight and quick movements. Anglers who do pursue Mooneyes often use light tackle and small lures or flies that mimic insects, making for a potentially rewarding fishing experience with these agile swimmers.

Mooneye fish are not currently listed as endangered or threatened. However, like many freshwater species, they face threats from habitat loss, pollution, and changes in water quality. Conservation efforts are important to maintain healthy populations, especially in areas where their habitat is at risk.

Mooneye fish are edible, and some anglers do enjoy them as table fare. They are known for their soft, white flesh which has a mild flavor. However, they are not widely sought after for culinary purposes, often overshadowed by more popular game fish. Those who eat Mooneye typically pan-fry or bake the fillets.