As a small fish swims through the water, it can seem vulnerable and exposed. Larger predators lurk all around, ready to snatch up these little swimmers and make them a quick meal. If you’re wondering what eats small fish, you’ve come to the right place!
If you’re short on time, here’s a quick answer to your question: small fish are preyed upon by a wide variety of larger aquatic animals like bigger fish, birds, marine mammals, reptiles, amphibians, and invertebrates.
Bony Fish
Larger Fish
Many larger fish species prey on smaller fish as part of their diet. This includes fish like salmon, tuna, cod, grouper, halibut, and snapper. These aggressive predators hunt using speed, stealth, and strategic hunting techniques.
Schools of bait fish like anchovies, herring, and sardines are often targeted by the swift and powerful open ocean hunters.
Eels
Slippery eels are well equipped for gobbling up small fish in their aquatic realm. Their slender, flexible bodies allow them to sneak through tight crevices and hide in rocky nooks where they wait to ambush unsuspecting prey.
Moray eels and snake eels have very sharp teeth for gripping wriggling fish and dislike releasing their victims once caught.
Catfish
Whiskered bottom feeders like catfish consume a variety of organisms including insect larvae, worms, crustaceans, plants, and yes smaller fish. Channel catfish, blue catfish, and flathead catfish lurk near the muddy bottoms of lakes, rivers and streams waiting for the chance to vacuum up any smaller creature that crosses their path with their vacuum-like mouths.
Bass and Sunfish
Many freshwater game fish like largemouth bass, smallmouth bass, and bluegill sunfish have voracious appetites for smaller bait fish like minnows, shiners, and darters. They expertly hunt smaller fish using strategic hiding spots in underwater structure and quick bursts of speed to overtake their prey.
A single adult bass can consume thousands of fingerling-sized fish per year.
Trout
Sport fish like rainbow trout, brown trout, and brook trout thrive on diets rich in smaller fish like minnows and shiners. Using their strong swimming abilities, keen eyesight, and lightning quick reflexes, trout precisely pick off unsuspecting little fish from below in a flash.
Their diverse diet typically includes 60-90% fish depending on food availability and habitat.
Piranhas
With razor sharp teeth, powerful jaws, and ferocious appetites, piranhas are efficient predators of small fish in South American rivers and lakes. Hunting in groups allows them to overwhelm and quickly skeletonize prey fish like tetras and mollies.
Despite their Hollywood reputation, piranhas rarely feed on large animals, focusing their remarkable abilities on easily captured small fish.
Sharks and Rays
Sharks
As apex predators, sharks feed on a wide variety of smaller fish and other marine animals. Their razor-sharp teeth and powerful jaws allow them to easily capture and devour smaller fish. Some species of sharks are known to hunt together in packs to corral and trap schools of small fish, making them easy pickings.
Small fish like anchovies, herring, and sardines make up a good part of many shark species’ diets. These small fish travel in large schools, making for an easy meal. Other small fish favored as prey include mackerel, menhaden, mullet, and minnows.
Sharks will also readily feed on smaller members of their own species. Essentially, if it’s small enough to fit in their mouths, sharks will eat it.
Certain shark species are especially dependent on small fish. For example, the whale shark’s diet is comprised nearly 90% of tiny plankton and small fish. Other sharks with specialized feeding habits include the cookiecutter shark, which takes circular bites of flesh from larger animals, and the enormous megamouth shark, which filters feeds on tiny organisms.
No small fish is safe from sharks!
Rays
Rays employ a range of hunting strategies to capture small fish and other prey. Many species use their wing-like pectoral fins to trap and pin down prey. Their excellent senses allow them to hone in on hidden fish buried in the sand.
Species like manta rays and bat rays will trap fish against the ocean floor before sucking them into their mouths. Skates shoot out their jaws to capture passing small fish as well.
Butterfly and eagle rays will use their pointed snouts to stun small fish by striking them. They then use suction to ingest the immobilized prey. Some rays like stingrays will partially bury themselves and attack when prey swims over them.
Their venomous tails allow them to easily subdue even fast moving fish. Overall the diversity of rays means virtually all small fish are hunted in some way.
Both sharks and rays employ a range of specialized hunting techniques for capturing small fish. Schools of anchovies, sardines, herring, and other diminutive swimmers must remain vigilant to avoid ending up as a meal for these powerful ocean predators!
Marine Mammals
Many marine mammals feed on small fish as part of their diet. These mighty hunters of the sea use their size, speed, and pack hunting strategies to prey on little swimmers.
Whales
Large baleen whales like humpbacks and blues eat huge amounts of tiny krill and small bait fish. Using baleen plates in their mouths, they filter massive gulps of water to trap prey. Toothed whales like orcas and sperm whales hunt big fish, but many also eat squid, octopuses, rays, and even seals.
Dolphins are toothed whales that work together to surround schools of small fish.
Dolphins
Dolphins use echolocation and coordinated hunting to corral small fish into tight balls, stunning them with their tails before gulping them down. Different dolphin species have different diets – bottlenose dolphins eat over 50 types of fish and invertebrates, while orcas hunt seals, sea lions, whales, squid, rays, and salmon.
Seals
Seals come in many varieties, from large leopard and elephant seals to small harbor and ringed seals. They eat a wide array of seafood like fish, octopuses, squid, krill and shellfish. Crabeater seals mainly eat Antarctic krill, while leopard seals hunt penguins, seals and krill.
Small seals need to watch for orca and sharks.
Sea Lions
Steller sea lions eat pollock, cod, salmon, rockfish, herring, squid and octopuses. They can reach 1000 lbs yet still chase quick fish. Sea lions hunt solo but also coordinate to herd fish into bait balls. California sea lions eat anchovies, mackerel, whiting and squid.
Their populations dropped when overfishing depleted their small prey.
Walruses
Walruses root along the ocean floor for clams, snails, crabs and small fish to vacuum up with their mighty whiskers. In between feeding dives they rest on sea ice or land. Walruses have even been known to eat seals and baby walruses when food is scarce.
Manatees
West Indian manatees are gentle herbivores that live in warm coastal waters, eating marine plants and freshwater vegetation. Baby manatees will also nibble on small fish and invertebrates as they nurse from mama manatees for up to two years.
Birds
Many species of birds prey on small fish as part of their diet. From seabirds that plunge into the ocean to snatch their aquatic prey, to wading birds that patiently stalk the shallows, to diving birds that submerge themselves completely to catch fish, birds have evolved a variety of techniques to catch these nutritious snacks.
Seabirds
Seabirds such as gulls, terns, puffins, murres, shearwaters and petrels often feed extensively on small fish. Gulls frequently hover over the water, then quickly plunge down and snatch fish near the surface. Terns make shallow dives for small fish and invertebrates.
Puffins, with their strong, thick beaks, are able to catch many small fish during a single dive under the water. Shearwaters and petrels use their hooked bills to snatch prey while pattering across the ocean surface.
Wading Birds
Long-legged wading birds like herons, egrets and ibises stalk patiently in shallow waters to spear fish with their sharp beaks. Great blue herons may stand motionless for minutes, waiting for the right moment to strike.
Reddish egrets have a unique feeding technique, using their feet to stir up small fish before catching them. White ibises sweep their beaks methodically through shallow water to feel for and capture hidden fish.
Diving Birds
Cormorants and anhingas are supremely adapted for diving to catch small fish. Their streamlined bodies, webbed feet and sharp beaks allow them to swim underwater effortlessly and snatch up panicked prey. They often swallow fish underwater before surfacing.
Loons and grebes are also strong swimmers and divers that can chase down speedy fish. Gannets, boobies and pelicans plunge into the ocean from flight, stunning small fish with the force of impact.
Reptiles and Amphibians
Sea Turtles
Sea turtles are ancient marine reptiles that have existed for over 100 million years. There are seven species of sea turtle, and they are found in tropical and subtropical oceans around the world. Sea turtles are large, air-breathing reptiles well adapted to life in the marine environment.
They have flippers for swimming and a hydrodynamic body shape. Adult sea turtles are primarily herbivorous, feeding on seagrasses and algae. However, hatchling and juvenile sea turtles are omnivorous and will prey on small fish, jellyfish, and invertebrates.
Their jaws are finely serrated which helps them catch slippery prey.
All species of sea turtle will opportunistically prey on small fish. This includes green sea turtles which are herbivorous as adults. Sea turtles locate prey using excellent eyesight. They are stealthy ambush predators. Their powerful jaws allow them to crush through the hard shells of mollusks.
Their hooked beak can grab and tear flesh. Sea turtles have been known to take fish off of fishing lines and even steal bait. Some areas where sea turtles commonly feed on small fish are coral reefs, seagrass beds, and mangrove habitats.
Snakes
Snakes are carnivorous reptiles that inhabit oceans, rivers, lakes, and land habitats around the world. There are over 3,000 species of snakes, and the vast majority are predatory. Most species of water snake and sea snake prey on small fish as a major part of their diet.
Even snakes that also eat other prey like frogs, rodents, or invertebrates will readily consume smaller fish species.
Snakes are well-adapted for catching fish with their slender shape, flexible jaws, and acute senses. Snakes locate prey using sight, smell, vibration sensitivity, and infrared detection. They strike quickly to grab fish in their jaws or swallow them whole.
Some snakes have rear-facing teeth to help grip slippery fish. Venomous sea snakes use their potent venom to rapidly immobilize and kill fish. Nonvenomous water snakes rely on constriction to suffocate fish prey. Overall, snakes are diverse and effective predators of small fish worldwide.
Crocodiles and Alligators
Crocodilians are semiaquatic reptiles that inhabit lakes, rivers, swamps, and coastal brackish waters in the tropics and subtropics. The two main types are crocodiles and alligators. These large, armored reptiles have formidable jaws filled with conical teeth ideal for capturing fish and other prey.
They are opportunistic apex predators that predominantly feed on fish, birds, mammals, turtles, and amphibians.
Small fish make up a substantial portion of juvenile and adult crocodilian diets. They use a combination of patient waiting and quick bursts of speed to ambush fish swimming by. The huge bite force and vice-like grip allows them to securely grasp fish once caught.
Crocodilians will also sweep their head side-to-side to herd fish into a tightly packed bait ball. This enables them to more easily grab multiple fish at once. Alligators in Florida have even been observed using lures to attract fish by balancing sticks and bones on their snout.
Frogs and Salamanders
Many species of frogs and salamanders are opportunistic predators that will readily consume small fish when the chance arises. As amphibians, they inhabit aquatic and moist environments where fish are plentiful. Frogs use their long, sticky tongues to catch prey while salamanders use their jaws.
Both have excellent vision to detect movement.
Some frog species are more adept fish eaters. The African bullfrog has a particularly large mouth and appetites. It is known to feed on juvenile fish such as tilapia. The South American pacman frog gets its name from its huge mouth and ability to swallow surprisingly large prey like small goldfish.
As for salamanders, larger aquatic species like mudpuppies and hellbenders sometimes eat minnows and other small fish they can fit in their mouth.
Invertebrates
Jellyfish
With their translucent, gelatinous bodies, jellyfish may seem harmless. However, many species are opportunistic predators of small fish. Their stinging tentacles allow them to capture prey easily. Once contact is made, venomous nematocysts on the tentacles discharge and paralyze the prey.
Jellyfish move slowly, relying on currents to bring food within reach. However, they can move quickly when pursuing prey by rapidly contracting their bell-shaped bodies. Species known to feast on small fish include lion’s mane jellyfish, sea nettles, and moon jellies.
Crabs
Crabs are adept hunters equipped with powerful claws to capture prey. They inhabit rocky reefs, sandy bottoms, and estuaries teeming with small fish. Crabs sit and wait patiently for prey to swim or drift near.
Then with lightning speed, they use their pinchers to grab their prey before popping it into their mouth. Some aggressive species, like blue crabs, will actively pursue and chase down fish. Their varied habitats and stealthy ambush tactics make crabs formidable predators of small fish.
Octopus
With their eight dexterous arms, camouflage capabilities, and beak-like mouths, octopuses are consummate hunters of small fish. They lie in wait for prey, often hiding in crevices and under rocks. When prey swims near, they launch attacks, using their arms to grab fish swiftly.
Their powerful beak can deliver a lethal bite, and venom in their saliva helps subdue prey. Intelligent and resourceful, octopuses have been known to logout fishing gear to capture bait fish. Their ingenious hunting methods and highly developed senses put small fish at a distinct disadvantage.
Lobsters
Lobsters are opportunistic predators that feed on a variety of small organisms, including fish. Their front claws are lined with sharp spines and equipped with muscles allowing them to grasp prey with immense force.
They typically hunt at night, emerging from their sheltered dens to prowl rocky reefs and shoals where fish congregate. Slow-moving bottom fish like eels and blennies are favorites. Though not the fastest hunters, lobsters can perform short bursts of speed to ambush their prey, grabbing small fish quickly before tearing them apart with their claws.
Crayfish
As omnivorous scavengers, crayfish feed on both plant and animal matter, including small fish. They use their sensitive antennae to detect prey and typically ambush fish under the cover of rocks or debris.
When threatened, crayfish can move rapidly backward with a powerful tail flip, allowing them to capture fish with a swift surprise attack. Once grasped in their large front claws, small fish rarely escape.
Some fish like minnows may avoid areas where crayfish are abundant to steer clear of these opportunistic predators.
Conclusion
As we’ve seen, small fish contend with a wide array of predators looking for an easy meal. From the tiniest minnow to a flashy betas, no small fish is completely safe from becoming prey. Larger fish, mammals, birds, reptiles, amphibians, and invertebrates all see small fish as tasty morsels.
The next time you see a small fish swimming in a stream, pond, or ocean, consider the many threats it faces from all sides and the constant struggle to avoid ending up as a predator’s dinner!
