Fish are vertebrates adapted to aquatic life, so their feeding occurs under water From mountain lakes to the depths of the ocean, fish have colonized the waters thanks to their various feeding techniques. There are species that feed on the remains of decomposing animals on the seabed, some are active hunters and others feed on plant matter.
If you want to know the types of food that fish eat, keep reading this article on our site and we will explain what fish eat, as well as the differences and most distinctive characteristics of the feeding of this animal group that inhabits the waters.
Types of fish feed
According to where the food comes from, fish are classified into different categories, although it should be noted that many species may present more than one mode of feedingand combine various techniques in order to obtain all the necessary nutrients. On the other hand, there are species that can live in the mouths of rivers, where the waters are brackish and, therefore, can survive both in rivers and in the sea, such as the bull shark (Carcharhinus leucas) or salmon. (Salmo salar), so their diet will be complementary between foods available in both types of environments. This occurs thanks to homeostasis , which is the ability of living beings to maintain a stable internal chemical balance.
Next, we will name the categories of fish according to their type of food:
- Herbivorous fish: obtain their food from plant sources, either higher plants or algae, depending on the depth where they live and their way of life. Some species have morphological adaptations in their bodies, such as the parrotfish (Scarus coelestinus), with its particular dentition, which groups its teeth in a structure similar to the beak of parrots, which it uses to gnaw at coral and rocks and thus be able to tear off the algae from these surfaces.
- Carnivorous fish: They feed on other fish and aquatic animals such as worms, crustaceans, molluscs and zooplankton. They can be active hunters or capture their prey by stalking. In addition, they have teeth adapted to tear the skin of their prey. Examples of carnivorous fish are the great white shark (Carcharodon carcharias) or the giant barracuda (Sphyraena barracuda), both with sharp teeth that work like real saws.
- Omnivorous fish: are those whose diet is more opportunistic and generalist, that is, they adapt to the availability of food, so that their diet can be of both animal and plant origin. Examples of omnivorous fish include the red-bellied piranha (Serrasalmus nattereri), which, although widely reputed to be a voracious carnivore, is not strictly so, as it can eat vegetation to supplement its diet. Another example is the common carp (Cyprinus carpio) which, in addition to feeding on aquatic vegetation, also looks for small insects or crustaceans at the bottom of the river or lake where it lives.
- Detritivorous fish: are those that take advantage of the organic remains of other fish and descend to the bottom. This serves as a recycling of organic material from aquatic environments, since in addition to feeding, many species filter the water, thus providing a very important service in these ecosystems. The catfish of the Siluriformes order are fish adapted for this type of feeding, such as the catfish (Panaque nigrolineatus). Also the fish called pool cleaners, such as the Corydoras aeneus, are the ones in charge of filtering the bottom of the bodies of water where they live.
If you have fish as a pet and they have stopped eating, this other article on Why won't my fish eat?
What do river fish eat?
River fish have body adaptations that allow them to live in less saline waters and their internal environment retains s alts, since these are not abundant in their external environment. As we mentioned before, there are different ways of feeding fish, so among those that inhabit rivers (whose waters have more phosphorus, potassium and magnesium) we can also find a great variability in their diet
The species responsible for filtering water, feed on detritus from the soil of rivers or lakes, and live and feed on the bottom, since they have a mouth apparatus adapted for it. Other species, such as river herbivores, feed on algae and vegetables and, sometimes, on fruits that fall into the water. On the other hand, the carnivorous fish present in this type of environment feed on insect larvae or river crustaceans. They can also eat other smaller fish and, in some cases, other land animals that fall into the water unsuspecting.
What do fish eat in the sea?
Like river fish, the species that inhabit the seas and oceans, whose waters are richer in sodium, iodine and chlorine, cannot live in fresh water because their body is not prepared to retain the s alts that the body needs, as we explain in this other article on Why do freshwater fish die in s altwater?
As they have adapted to living with s alt around them, their body is in charge of regulating its continuous entry and exit. Marine species include in their diet a wide variety of foods This will depend on their mode of feeding (herbivores, carnivores, omnivores or detritivores) and the place where they live in the seas. So much so, that the inhabitants of the deep sea, such as abyssal fish and other deep sea animals, adapted to live in areas of the sea where life is very scarce, can feed on the zooplankton and small minnows However, other species, such as deep-sea fish (Eurypharynx pelecanoides), can be predators and catch larger fish.
On the other hand, species such as sharks, tuna or swordfish are pelagic fish, that is, they live closer to the surface. They are great hunters and predators, actively taking their prey. Other species, such as the clownfish (Amphiprion ocellaris), are considered to be generalist omnivores, since they feed on both algae and animals in the same proportion, and have also been observed consuming the parasites of the anemones where they live, with which they are mutualists, that is, they benefit from both species to improve their lives.
Then there are marine species with more curious eating habits, such as the pilot fish (Naucrates ductor), which feeds on the remains of food and parasitesof the sharks, with whom they form a practically symbiotic relationship, since it is difficult to see the two apart.
Now that you know what s altwater fish eat, you might also be interested in learning about some of the most beautiful s altwater fish around.
What do freshwater fish eat?
Freshwater fish are those that inhabit rivers, lakes, ponds and wetlands, whose salinity (s alt content) is less than 1.05% and is decisive for their survival.
The fish that inhabit these waters feed on algae and microscopic species that make up the plankton, although they can also eat other fish and debris of other animals. In addition, there are species that can come to the surface and feed on insects and larvae that they find there.
In addition to freshwater fish, you may be interested in these other coldwater fish.
What do small fish eat?
Most small fish feed on larvae, invertebrates and small aquatic animals. On the other hand, small fish need to consume more food than large fish (in proportion to their size), since their energy needs are greater, due to their high metabolism and activity.
In the case of fingerlings, that is, young and small fish, they consume microscopic algae and plankton, since the size of his mouth does not allow him to eat larger foods. As they grow, their eating habits are modified until they reach the feeding of the adult fish.
If you want to adopt small fish, you may find this other article on Fish for small aquariums useful.
What do aquarium fish eat?
When we decide to have fish as pets, we must be aware that they require special care and that we should only have species that are allowed, just as it is very important to know their habitat of origin and what they eat in the wild. Depending on the species, they can consume natural and live foods present in the fish tank or pond, such as:
- Detritus.
- Plankton.
- Worms.
- Insects.
- Snails.
- Other fish.
The abundance of these foods will depend on their quality, the presence of aquatic plants or algae and the cover of the bottom, such as rocks and aquatic grasses.
On the other hand, the complementary foods must be supplied on a regular basis and, depending on the species, so will the number of times a day to be supplied. These are made up of mixtures of carefully selected ingredients to provide all the nutritional elements necessary for the development of the fish. They should be made in a way that is easy to eat and digest.
These complementary foods come in the form of flakes, flakes or pellets, and their ingredients will vary depending on the species of fish they feed. goes to. For example, they can be composed of algae or crustaceans for carnivorous species. Great attention and care must be taken when selecting the right food for our aquarium fish, taking into account their natural characteristics and whether they are freshwater or s altwater.
