Pisces, like all other animals, need food to live, grow and reproduce. Food provides the energy needed to maintain metabolic processes in fish, and in addition, it contains everything that is required for the growth and development of tissues.
The main categories of nutrients needed by fish are proteins, lipids (fats) and carbohydrates, as well as a certain amount of certain minerals and biochemical substances – in particular, vitamins. Fish differ from other vertebrates in the relative amount of nutrients they need.
In particular, many groups of fish (especially predatory) can absorb a higher percentage of dietary proteins (from 35 to 55%) than birds and mammals that are able to digest up to 25% of proteins.
There is also some difference in the amount of food consumed by fish compared to other animals. In addition, as will be shown below, fish of different species also differ from each other in terms of feeding.
Eating fish in nature
In order to properly feed fish in captivity, it is important to know how they eat in the wild and what eating habits that fish have for each particular species.
In the wild, fish use very diverse food sources. Potential food includes the following types: decomposing organic matter; bacteria; protozoa and other microorganisms; aquatic plants and algae; fruit and seeds; invertebrates (for example, insects, worms, snails, crustaceans); other fish; amphibians, and sometimes even birds, reptiles, and mammals.
Not all fish are able to eat any kind of food – most of them, to varying degrees, specialize in a particular type of food. For example, some fish mainly use plant foods — they are called herbivores or herbivores. Others, including many large catfish and some characteristic, prefer animal food (live or dead) – such fish are called carnivorous.
Perhaps the most famous – or rather, the infamous – freshwater carnivorous fish are the red-bellied piranha Serrasalmus nattereri, the larger relatives of tetras.
Most fish feed on a rather varied diet; vegetable and animal foods are included in their diet. Such fish are called omnivores. Aquarists often consider barbs (carp family) herbivores, but anyone who watches the small barbs in an aquarium knows that they readily eat Daphnia daphnia and Tubifex tubers, as well as other live food (see below).
There are also species of fish that demonstrate a very peculiar behavior associated with food. It happens that fish eat very strange food, such as, for example, the geniochromis Genyochromis mento and some other species of the tsikhlovy family, which feed exclusively on the scales and fins of live fish.
Such fish are called lepidophages, or scales. Most of our knowledge of the natural food of fish is obtained by careful analysis of the intestinal contents of individuals caught in the wild.
Although most fish in an aquarium environment consume “unnatural” food, it is very important at the same time to give them food suitable for their digestive system. For example, herbivores and omnivores usually have a very long intestine and practically no real stomach, that is, their digestive system is adapted to digest food that comes in constantly and at the same time in small portions.
Carnivorous fish, on the contrary, usually have a stomach that can accommodate and partially digest rather voluminous pieces of food, after which they undergo further absorption in a relatively short intestine. It is obvious that feeding herbivorous fish with large pieces of food, for example, offering them whole dead fish is just as unacceptable as offering lettuce to carnivorous fish.
During the life of the fish, the preferred types of food for it may vary. The size and type of food may depend on the size of the fish (in particular, on the size of its mouth) and the stage of its development.
For example, the fry of predators are unlikely to be able to find somewhere other fish, so small that they can eat it. In the same way, young fish of species that eat mollusks usually cannot crush a snail until they become adults.
In addition, in the wild nature of the species and the amount of food available to fish, and consequently, their diet is influenced by environmental factors such as water temperature and season.
Fish differ from each other not only in that they prefer a certain diet (that is, food of a certain type), but also in behavior during feeding. Predatory fish usually set up an ambush, quietly approaching their prey, or motionlessly freeze in place, waiting for a suitable victim to swim past.
In contrast, predators, usually pursuing prey, rely mainly on their speed, trying to overtake and grab the prey. Other species of fish, such as Molly Poecilia sphenops, can spend many hours eating algae and other plant foods.
The physical means by which fish obtain food may vary considerably. For example, some fish take in suction movements, capturing small pieces of food, which are then usually swallowed whole.
Most aquarium fish show such grasping movements, feeding on free-floating live food, such as Daphnia Daphnia and Artemia Artemia. Food of herbivorous fish consists of living or decaying plant tissue (sometimes among them there are leaves that have fallen into the water). I write such a fish, biting off pieces of plants or picking them up entirely.
Some herbivorous fish eat mainly algae. An example of this is the catfish of the plecostomus plecostomus. He has a modified mouth-sucker that allows him to stick to the stones on which he sticks algae.
Large carnivorous carnivorous fish squeeze the resisting prey with their teeth until they manage to swallow it whole or break it into small pieces. They do this with the help of one or several rows of sharp teeth piercing the body of the victim in order to prevent her from swimming away.
Other aspects of nutritional behavior
The amount of food and the frequency of its reception may vary in fish of different species, and in addition, usually depend on the size of prey. For example, large predatory fish, such as the red-tailed catfish Phractocephalus hemioliopterus, are accustomed to eat a large portion of food at once in one go – for example, to eat whole fish, and this is enough for them for several days. At the other extreme, some herbivorous fish, in particular, Molly Poecilia sphenops, spend a lot of time tweaking algae or snatching out fine food from the water.
The required amount of food and the frequency of its intake may also depend on the stage of development or the reproductive state of the individual, as well as on environmental factors such as the seasonal availability of certain types of food and water temperature.
An aquarist should take into account another important aspect of the behavior of fish in relation to food, namely, what position does a fish occupy in water when it feeds. For example, the majority of catfish and loach feeds mainly on the ground, while some calves and live bears feed mainly on the surface of the water. Between these two extremes there are other fish that feed in the water column, these include most of the popular aquarium fish species, including almost all barbs, rasbora and tetras.
The location of the jaws of a fish is a useful, though not unmistakable, sign indicating in which horizon of water it feeds. If the jaws of the fish are directed down or low, then this fish usually eats at the bottom, the fish with jaws pointing forward feed in the middle layers of the water, and with the jaws directed upward, on the surface of the water.
Many fish are able to eat at any level. However, some (in particular those whose jaws are oriented downward) find it difficult to take food at other levels, especially if they are forced to eat on the surface of the water, as they also have to take a completely unnatural posture for them. In addition, some species of fish in general are very reluctant to leave their preferred level – in all likelihood, this is due to the innate instinct, forcing them to avoid predators.
Therefore, not all bottom fish rise to the surface of the water in order to take floating food, and some surface fish do not want to swim following food to the bottom through the entire water column.
When selecting compatible fish species for a common aquarium, their natural eating habits should be considered. Fish that require a special diet or exhibit unusual behavior during feeding, it is sometimes better to keep in a specific aquarium (that is, in an aquarium where only one species of fish is present), where everything can be adapted specifically for their needs.
It is unreasonable to ignore these special needs or to expect that the fish of this species will adapt themselves to what they are offered. Most likely, such ignoring of their features will lead to the appearance of health problems or even to the death of pets.
It is extremely important to ensure that all the inhabitants of the aquarium receive enough food. At the same time for the fish of each species it is necessary to provide a suitable type of food.
There is no point in offering lettuce leaves to apparently predatory fish or large chunks of fish meat – herbivore. “Food incompatibility” can be associated with behavior during feeding (for example, many predators do not perceive immobile food as edible), as well as differences in the digestive system: in particular, the intestine of herbivorous fish is not adapted to digest large pieces of food, and the intestine is carnivorous cannot absorb plant matter.
These considerations are especially important for a general aquarium, as it contains fish of different species, differing from each other in their food requirements and behavior during feeding. For example, bottom catfishes and loaches may well remain generally hungry, since the former usually grab the food of fish swimming in the middle layers of the water or near its surface. There are feeds that have the ability to quickly sink – pellets, tablets and plates – they are designed specifically for bottom fish.
However, you can not use only such food, if the aquarium has fish that feed exclusively on the surface of the water.
The nutritional value of the diet is crucial to the overall well-being of fish. Fish that are regularly malnourished may experience slow growth. In severe cases, they may develop symptoms of a deficiency in the necessary elements, such as diseases of the skin and eyes.
A healthy diet is also necessary to maintain a natural infection immunity in fish.
The most popular aquarium feed
Under the conditions of an aquarium, it is almost impossible to provide the fish with a complete set of natural food. For this, it would be necessary to supply them with tropical aquatic invertebrates, plants, algae, etc., and to provide the food necessary for the fish of this particular species, all this would have to be collected in the natural environment where these fish live.
Instead, it’s better to look for more affordable feed sources.
Fortunately, aquarium fish of most species, especially those grown in fish breeding, willingly take artificial food. The proportion of fish caught in the wild is relatively small, and it may take some time to wean these fish from natural food and train them in an artificial diet.
It happens that the fish refuses to take any food other than live food. Some species of fish, mainly fish-eating ones, such as the live-bearing pike Belonesox belizanus, are known for being very difficult to teach them to non-living food.
Therefore, before deciding to keep such fish in your tank, an aquarist must be sure that they can provide them with suitable live prey all year round.
Feed for aquarium fish, commercially available
When a hobby like aquaria was born, the fish food was usually caught or prepared by aquarists themselves. Common types of food were food debris from the kitchen, such as beef heart, hard-boiled egg yolk, vegetables, as well as live food, such as earthworms and Tubifex.
Many of these types of feed are still popular in our time.
Nowadays, the trading network has a large variety of high-quality dry, frozen and live food for tropical aquarium fish. Examples of these feeds are given below.
Although many species of fish can eat exceptionally dry food, a varied diet will benefit them. Therefore, from time to time it is worth giving them fresh or frozen food.
The latter are particularly popular with many aquarists. Such feed must be stored in the freezer or in the freezer compartment of the refrigerator. An industrial freezing process, sometimes involving gamma irradiation, kills most pathogens that affect fish.
Therefore, giving fish food subjected to gamma irradiation and freezing is much safer than feeding the same food live.
Some types of feed for aquarium fish, listed below in the “live feed” section, are also sold frozen.
If you have purchased frozen food for your pets, first defrost it or let it thaw quickly in a net under running cold water from a tap and then feed it to fish. If this is not done, the fish’s stomach may cool down excessively. In addition, ice crystals contained in frozen food can pierce the intestinal wall of small fish.
The liquid content should be drained away – the fish will not be able to absorb it anyway, therefore the organic matter contained in it will only pollute the aquarium in vain.
Live food, especially aquatic invertebrates, form a very important part of the diet of many wild fish. For example, fish that feed on the surface of the water may eat large numbers of aquatic and terrestrial insects.
Insects fall on the surface of the water, and they are captured by a surface film. Other species of fish, such as benthic fish, feed on the soil by larvae of aquatic insects, crustaceans and worms living in bottom sediments.
As noted above, supplying aquarium fish to invertebrates from their natural habitat is an absolutely impossible task for most aquarists. However, in many cases it is still possible to provide them with prey of approximately the same type, for example, mosquito larvae and small crustaceans.
Live food has many advantages. Most of them have a high nutritional value, and the basic vitamins and other nutrients they contain remain intact and will not collapse during processing, as happens during the preparation of some dry food.
Fish have natural feeding instincts (even those derived in fish water). Therefore, they usually respond more vigorously to moving prey than to fixed feed. In fact, fry of many species and even some adult fish generally recognize only moving food as edible, so if you give them only dry and frozen food, they can go hungry.
Industry engaged in the manufacture of fish feed, innovates, trying to somehow “revive” dry food. To do this, they include special chemicals that emit gas bubbles and set in motion the feed in the water.
However, so far these attempts have been unsuccessful.
The main negative aspect of feeding fish with live food is the risk of introducing diseases and parasites. Pathogenic microorganisms (bacteria, viruses), as well as parasites may be present in the internal organs or body tissues of organisms used as live food. In addition, the natural water in which such live food is collected can itself become a source of disease or parasites.
Freshwater crustaceans, such as Cyclops Cyclops, may contain parasitic worm larvae (helminths), and the Tubifex tubule is known for carrying pathogenic viruses, bacteria, and even some protozoan parasites. Live food, intensively grown in open systems, where there are no fish, are much less likely to carry such diseases. However, aquarists have no reliable means to distinguish specially grown live food from the same food collected in any local pond or river.
Special treatment of water or purification of live feeds can rid them of some parasites and pathogens, but these procedures cannot be fully relied on, since they cannot destroy the causative agents of all possible diseases found in feeds. Thus, the risk of bringing diseases into the aquarium together with live food is very significant, and the aquarist should always remember this.
Some types of live feed:
Daphnia, or Daphnia water fleas, Bosmina Bosmina, Cyclops Cyclops and other free-floating freshwater crustaceans are found in almost every reservoir, some of which can be purchased at aquarium stores.
Country ponds, barrels of water and other large containers can be “sown” with daphnias purchased or collected in the wild to ensure an adequate supply of them. Their natural food is microorganisms, including free-floating unicellular algae (“green water”). Ponds with ducks or geese are ideal sources of crustaceans, since the constant fertilization of algae with birds provides sustainable food supplies for crustaceans.
To cultivate algae in containers with water, an aquarist should use both his imagination and experience: it is known that immersion of horse manure in water (such water must be filtered before use!), And also hay produced good results. If a pond or a container of water is illuminated daily for a while by the sun, the algae and crustaceans will multiply rapidly there.
However, overheating should be avoided.
To collect such feed, use a net of material with suitable sized cells. If you catch crustaceans in ponds, it is useful to have a net with a long handle, although this is not decisive – in fact, crustaceans are often collected on shallow banks heated by the sun near the shore.
For the needs of an average aquarist, it will be quite enough to have an aquarium net tightly attached to a long bamboo stick. Without the usual food supplies, these creatures can live no more than one or two days in small vessels with water, so it’s best to catch as many crustaceans as you need for immediate use.
They should be transported in a bucket of clean water, and this water should not be poured from the pond where they were caught.
Do not forget to check whether there are any predatory creatures in your “catch”, such as dragonfly larvae or cornetra larvae (see below), especially if you feed small fish.
The catch caught in the ponds, you can sort and select from her feed of different sizes for fish of different sizes. This can be done using sieves or nets with different cell sizes.
Such a grid can be made independently (for example, from nylon tulle curtains or you can use different aquarium nets for this purpose) or you can buy (there are special sieves for live food available).
If you keep crustaceans in a bucket all day or longer, then very small specimens will appear in the water – nauplii. They can be filtered through a sieve with very small cells or a piece of cloth and used as feed for fry.
In addition, water containing such food can be directly poured into the aquarium with fry, but only in small portions in order to prevent hypothermia.
Larger crustaceans, in particular, Gammarus gammarus (bokoplavov) and Asellus azelus (water lice) can be collected in heavily overgrown ponds and under stones. The filling holes of the artificial ponds are also their favorite secluded places, and they can be “sown” there to form an adequate supply.
Crustaceans from salt water bodies
Artemia, or Artemia sea shrimp that have just emerged from eggs (nauplii), are commonly used as fry food (see below). In recent years, live adult brine shrimp are sold in some retail outlets for feeding large fish.
True, they are quite expensive, but it is an excellent feed. Before feeding artemia to fish, be sure to rinse them with tap water so that salt does not accumulate in the aquarium.
Aquatic insect larvae
Motyl (red larvae of mosquitoes) – these are the larvae of ringing mosquitoes. They are usually found in detritus accumulations at the bottom of ponds or other bodies of water with standing or slowly flowing water, the bottom of which is covered with silt or other organic matter, or densely overgrown with algae (mud). These are blood-red larvae approximately 1-2 cm in size.
Sometimes they can be purchased at pet stores, but we do not recommend this, as some sources of their prey are highly contaminated, and infected bloodworms can become a breeding ground for pathogenic microorganisms. A person who has completely devoted himself to such a hobby as aquariums, can collect moths in safe places by himself, but for this he will have to select individual larvae from detritus using tweezers.
Therefore, the easiest and most secure option is to buy a frozen product that has been disinfected.
Coretra (white larvae of mosquitoes) are the transparent larvae of non-blood sucking mosquitoes, Chaoborus spp. They are about the same size as bloodworms, and they can sometimes be found among the crustaceans living in ponds. However, they are rarely found in such large quantities as to constitute a separate type of food.
Fish love them very much, but these larvae are predators and should not be used as food in those aquariums where there are fry.
Devils (black mosquito larvae) in length can reach 1 cm and usually hang in standing water directly below the surface. They breathe air using a small tube, with which they take atmospheric air just above the water surface.
At the slightest sign of danger – even when a shadow falls on the water – they dive into the depths, so the net needs to be moved imperceptibly. Feeders for horses and livestock, ponds and even buckets of rainwater can be rich sources of these larvae.
They can be caught and transported in the same way as daphnia, etc. The fish love this food very much, and there is no evidence that it can conceal any danger. However, be sure to ensure that all the larvae are eaten – otherwise in the tropical conditions of the aquarium, they quickly turn into mosquitoes!
The rats are the larvae of the bee-talker-hopper, the grayish worms; their body length is about 1 cm, diameter is 3 mm. They have a long air tube (“tail”).
They can sometimes be found in ponds and other bodies of water with stagnant water. For fish with a mouth large enough, they are a favorite food.
A variety of different worms are used as feed for aquarium fish. Some worms are specially grown, others are harvested in nature or bought.
Earthworms – Excellent food for aquarium fish. Before use, they should be rinsed in water to clear the soil, and then fed to the fish as a whole or cut into pieces, depending on the ratio of the size of the worms and fish. They can also be ground in a kitchen blender (best of all in a special blender that serves only for this purpose) – this way you can make excellent food for fry.
Worms can sometimes be bought, but for most aquarists, such food is a free additional product as a result of working in the garden. Remember that earthworms should not be harvested in land that has recently been treated with pesticides or other chemical means.
These worms can also be bred in large boxes, usually wooden. The crates are filled with compost rich in organic matter. Worms are fed plant waste from the kitchen, laying them on the surface of the compost.
If the box has no bottom and stands right on the ground, the worms will populate it themselves, and then, when you collect them, populate it again, if you only maintain the necessary food supplies for them there. Of course, if there is no food in the box without a bottom, the remaining worms, being free, may well leave it.
Alternatively, you can use boxes that are closed on all sides, but they will not produce such a large “harvest”, since it takes some time to allow the worms to multiply and replenish the population. The advantage of artificial cultivation of worms is that in this way it is possible to maintain a supply of worms even when the garden freezes (with thermal insulation) or when the ground is hard as a stone as a result of drought (with watering).
The culture of the worms should be in the shade so that in hot sunny weather they do not overheat.
Tube maker Tubifex are small (about 2.0-2.5 cm in length) reddish worms living in the wild. Usually they are found in accumulations of dirt and garbage – for example, gutters, and collecting them is not the most pleasant thing. It is better to buy these worms in pet stores.
We note here that despite assurances that various disinfectants and mechanical methods are used to clean the pipe-maker, it should be emphasized that feeding the fish with a live pipe-maker is one of the surest ways to bring any disease into the aquarium. Therefore, although we do not deny that fish love this food very much, it’s not worth the risk.
It is much safer to use a freeze-dried pipe straw or frozen and disinfected.
Enhitrei Enchytraeus spp. – These are worms approximately 1-3 cm long, white. Sometimes they can be found in soil rich in organic matter. But for use as an aquarium feed, they are usually grown artificially using a store-bought culture.
They are bred in a shallow (4-5 cm deep) plastic or wooden box of suitable sizes (for example, 20 x 30 cm), into which a loose, organic-rich soil (substrate) should be poured; You can mix it with peat. The soil should be kept wet, in no case bringing to damp. For this purpose, the culture of worms is usually covered with a sheet of glass, and on top with thin plywood, cardboard, etc., since the worms, among other things, need darkness.
However, the culture should not be hermetically sealed, otherwise the worms will suffocate.
Enchitree culture can be fed with one or more pieces of bread dipped in water or low-fat milk. Other types of food for white worms are cereals, such as oats. Some aquarists feed their worms with aquarium feed – flakes.
It should be remembered: whatever food you give to worms, it must be moist. The amount of food and frequency of feedings required for worms are established experimentally, and if the feed starts to decompose, it should be replaced.
Worms should not be harvested until culture is fully established. This can be determined by lifting the lid, by the accumulation of worms gathering around food.
In addition, do not need to collect too many worms. Take them with tweezers.
If the substrate has the right consistency and moisture content, the worms usually come out clean and can be fed to the fish immediately. Otherwise, rinse them in water. You can feed them fish with the help of special feeding troughs (which can be purchased at pet stores), designed for fish that feed on the surface of the water and in its middle layers.
Fishes eating at the bottom of the worms, you can just throw in the aquarium.
The old culture of worms is gradually being depleted and becoming less fertile, and it must be allowed to rest, replacing part of the substrate. After that, it will take about a week for the “harvest” to increase again.
You can create a new culture, using part of the old for “sowing”.
Grindal worms – it is a smaller (0.5 cm long) species of Enchytraeus. They are sometimes used as food for grown fry or small fish, such as dwarf cichlids, small tetras, etc. These worms are bred at home, and the starting culture can be ordered only from specialized suppliers. The substrate should be the same as for the breeding of enchitree, but Grindal worms are usually kept in smaller containers, for example in plastic sandwich makers.
Worm culture should be covered up and kept in the dark. You need to take a few cereals (for example, oats) and scatter them over the surface of the compost in a small area, forming a circle with a diameter of 3-4 cm, then slightly moisten and cover with a small piece of glass. When the worms eat this food, a lot of them will accumulate on the underside of the glass, and from there they can be washed away directly into the aquarium.
These worms are too small, so they do not need to be rinsed to clean the soil. After some time, already having experience in breeding Grindal worms, it will be possible to establish the necessary consistency and moisture of the compost, at which it will not stick to the glass.
Grindal worms are not very prolific, so care should be taken not to collect too much of them at once, otherwise the culture can be over-depleted.
Microworms are usually used as feed for young fish, but they can also be fed to very small adult fish (see below).
Other possible live feeds
Mokrits are very fond of fish of various sizes – from medium to large, although it may take time to learn how to grab them. Larger fish like crickets – you can buy them at pet stores that specialize in reptiles (lizards, etc.).
Flies and other insects, both terrestrial and aquatic, can also be a delicacy for fish, but those that go to feed should not be exposed to insecticides, that is, they should be caught, not sprayed from cans! Domestic flies, as well as white, green and black flies are suitable for this purpose. Stinging insects is best avoided.
Maggots serving as bait during fishing are sometimes also used as live food for aquarium fish, but you should not use painted larvae for this purpose, since the paint can be toxic. Maggots are best kept in a bait box or in some other plastic container with a tight-fitting lid with holes for air access. The larvae of flies, like the larvae of mosquitoes, can turn into adult insects, especially in the heat, and you only have to open the container, as the whole house is immediately filled with flies!
For this reason, in order to artificially slow down their development, they should be kept in the refrigerator. Drosophila, or fruit flies of Drosophila, preferably wingless, can be diluted as food for fish that feed exclusively on the surface of the water.
The original culture along with instructions can be purchased from some pet suppliers – for example from reptiles or amphibians. Fruit flies are usually diluted in glass bottles filled with a mixture of oatmeal, sugar and yeast and plugged with sponge stoppers.
Among aquatic insects, the combing of Notonecta spp. and water strider Gerris spp.
Some fish are very fond of fragmented aquatic snails, but for this purpose you should only use aquarium snails, as wild can be carriers of parasites.
Live fish can serve as food for predators, although most of them can be taught to eat dead fish, as well as other types of food for predators, as soon as they learn to associate with food what their owner puts in an aquarium. However, some aquarists seem to deliberately feed live fish or even live mammals (such as mice) to predators, especially carnivorous piranhas, and enjoy this “performance”.
Fortunately, the use of “fish feeders” – healthy fish, bought exclusively as food for predators – has not received wide recognition in some countries, particularly in the UK, and many believe that this practice should be universally condemned.
Fish lovers sometimes use ugly, weak or unnecessary fish for some other reason as food for other fish – after all, this is the fate of most fry in the wild. Rejection of fry is sometimes necessary when breeding fish that produce numerous offspring, especially if the need for young fish is small, as, for example, in the case of Central American cichlids.
The use of weed fish as food is usually considered acceptable if you take into account that you would still have to get rid of them one way or another.
It is very important in no case to get rid of sick fish, feeding them to other fish, as this can lead to the transmission of diseases. For the same reason, do not let the fish eat the bodies of dead or dying neighbors in the aquarium.