Ternetia is a fish known to many aquarium lovers, although it is often known under a different name – black tetra. It is popular as a pet because of its relative unpretentiousness, eye-catching appearance and variety of colors. In addition, it gets along well in an aquarium with many other species. All this makes it a good choice for those who are just getting started with aquarium fish.

Origin of the species and description

Photo: Ternetia

Photo: Ternetia

The very first fish-like creatures arose a very long time ago: about 530 million years ago. They were not yet fish, but among such jawless animals, like Haikouichthys, there were also the ancestors of fish.

The fish themselves also appeared about 430 million years ago. Although the species that lived in the ancient oceans all died out and bore little resemblance to modern ones, further evolution in general terms has already been traced since those times, and those species were the ancestors of those inhabiting the planet now.

Video: Ternetia

The first flourishing of the fish was reached after the appearance of the jaws, the species diversity increased greatly from the Silurian period, and remained at a high level until the Permian extinction. Then most of the species disappeared, and the rest gave rise to a new round of growth in species diversity in the Mesozoic era.

It was then that a detachment of characiniformes arose, which includes blackthorn. The oldest extinct fish, Santanichthys, is 115 million years old. Until the end of the Cretaceous period, many other species of characins arose, but then they all became extinct.

Most did so during the Cretaceous-Paleogene extinction. But some species remained, and modern ones originated from them, including blackthorn. The earliest fossil finds of representatives of the genus Ternetia date back to the late Miocene, they are about 9-11 million years old, and they were made in Central America.

The description of the species was made by A. Boulenger in 1895, the name in Latin is Gymnocorymbus ternetzi. Thorns were kept as aquarium fish decades later.

Appearance and features

Photo: What a thorn looks like

Photo: What a thorn looks like

Thorns are small: 3.5-5 cm, but by the standards of the aquarium, it is even larger than average. Their body is flat and wide. The usual thorn is silvery, three dark stripes are visible on its sides. Females and males differ little: males are slightly smaller and brighter, their fin is slightly more pointed and longer.

The fins are translucent, except for the large anal fin, it is he who distinguishes the thorns, thanks to him it has become so common as an aquarium fish. A small adipose fin is noticeable just in front of the tail – it is characteristic of fish belonging to the haracin family.

This fish has this appearance in nature, but other color variations were bred for aquariums, and very different ones: red, blue , green, orange, lilac – the colors are very bright. As the fish mature, they gradually become paler, especially for those whose color is unnatural.

Common subspecies:

  • veil – has large wavy fins;
  • gold – colored in a golden hue, without stripes;
  • genetically modified – a very bright color, especially under ultraviolet light.

An interesting fact: Although these fish themselves are almost harmless, bloodthirsty piranhas are their close relatives, they belong to the same order of characins , as evidenced by the resemblance between these fish.

Now you know how to care for thorn fish. Let’s find out where they live in their natural environment.

Where does the blackthorn live?

Photo: Blackthorn fish

Photo: Thornfish

In nature, this fish can be found in South America, in Brazil and Paraguay.

It inhabits the basins of several large tributaries of the Amazon, such as:

  • Rio Negro;
  • Guapore;
  • Parana;
  • Madeira;
  • Paraiba do Sul.

For Ternetia prefers unhurried lowland rivers, abundantly overgrown with vegetation. This does not mean that fish lives only in large rivers: it also lives in small rivers, and even streams – the main thing is that they are not too fast.

The water in such slow-flowing reservoirs is soft, in addition, it is quite acidic – and thorns very much prefer this. They also love shady areas, and you can usually find them in a pond in those places that are next to trees, in their shade. Prefer rivers with dark water rather than clear water.

They usually swim in the upper layer of the water, where it is easier to find their preferred food. In an aquarium, they can swim in any layer, and when keeping them, in order to ensure the comfort of the fish, the main thing is that there are more plants, and in the middle there is a zone for free swimming.

The fish came to Europe in the 1930s and quickly spread widely among aquarium owners. This was facilitated by the fact that the blackthorn easily endured captivity and multiplied in aquariums.

What does the blackthorn eat?

Photo: Blackthorn female

Photo: Blackthorn female

In the natural environment, the basis of nutrition of this fish:

  • insects;
  • their larvae.
  • worms;
  • small crustaceans.

Usually the reservoirs in which the blackthorn lives abound in this kind of food. Moreover, this fish is unpretentious and not particularly picky about food: it can eat almost any small liveliness that it can only catch. It is food of animal origin that prevails in its menu, and it should be fed accordingly in the aquarium.

It can be given both live and frozen food, the fish will eat daphnia, brine shrimp, bloodworms with pleasure. It prefers to take food at the very edge of the water or in the middle layer; due to the location of the mouth, it does not raise it from the bottom. If you give a lot of food at once, the fish can overeat, and the constant excess of the norm will lead to the fact that they become fat beyond measure.

Given this, it is preferable to give them such food that will sink to the bottom slowly, while strictly dosing it. Then the fish will eat everything and the bottom will not be clogged. The thorn itself is undemanding, but it should be remembered that it must be fed in a balanced way, you cannot give the same thing day after day.

Dry food should be interspersed with live food, few components of plant origin should be introduced into the diet. If the blackthorn feeds too monotonously, it will start to get sick more often, it will multiply worse, and metabolic disturbances of the fish are possible.

Many mixtures sold in stores designed for tropical species are suitable for it. Food options containing natural dyes will be useful – by eating them, the blackthorn regains its former brightness. Fry and only individuals transferred to a new aquarium need vitamin supplements.

Character and lifestyle features

Photo: Blackthorn male

Photo: Blackthorn male

Thorns are preferred in wildlife small rivers or even streams, live in small flocks of 10-20 individuals, while they are very active, constantly hunt, scare away smaller fish and can even attack each other.

Most often, such attacks do not end in serious injuries, both opponents remain in the pack and cease to conflict; However, sometimes only for a while. Thorns swim away from predators in different directions, after which they gather again only when they are full and stop hunting.

In an aquarium, the behavior of fish largely depends on its volume. If it is spacious, then thorns usually swim in the middle layer and spend most of their time in free water. If the aquarium is cramped, they behave very differently: they mostly hide behind plants, and only come out to eat.

For thorns, an aquarium of at least 60 liters is required, it must have soil and plants. This volume is enough for ten individuals. It is required that the aquarium is well lit, and the water temperature in it is slightly above 20 ° C. Water changes should be carried out every two days, 30-40% of its total volume should be updated per week.

Ternetia gets along well with other fish, although it depends on their species. It is best to keep it together with other characins, platies, guppies. Unfriendly to small or veil-finned fish. The thorns themselves should be at least 3-4, and preferably 7-10, if you put only one fish of this species in the aquarium, it will show aggression towards its neighbors.

The same applies to too small flocks. With a normal number, the attention of the fish is mostly occupied by fellow tribesmen, they spend most of the time with each other, and even if fights arise between them, they practically do no harm. In such a flock, the fish will frolic and delight the eye.

The soil in the aquarium should consist of sand or fine gravel – as in its natural habitats. At the bottom you can put a few small snags. It is best to dim the light, you can do this with the help of plants floating on the surface – this will also create an environment close to that in which the fish live in nature.

It is highly desirable to enrich the water with oxygen, it is also useful to use one of the air conditioners that create the effect of “dark water”. If you do all of the above, thorns will feel at home in the aquarium, although the fish are unpretentious, so compromises are possible.

Interesting fact: An aquarium with thorns must be covered, because they are able to jump very high, so they can even jump out of it.

Social Structure and Reproduction

Photo: Colored thorn

Photo: Colored thorn

Although flocks of thorns are small, a hierarchy is created inside them, fights are not uncommon in which males find out who is stronger and will enjoy the priority attention of females. Fish do not get serious wounds in such fights, so you can ignore them. In aquarium conditions, it is preferable that they spawn in pairs, although schooling spawning is sometimes possible. For spawning, a special aquarium is used, designed for 30-35 liters. It should contain very warm water: 25-26 °C, hardness should be 4 dH, and acidity should be 7.0 pH.

Before spawning, preparation is needed: the male and female are seated and kept separately for a week, giving them high-protein food. At first, only the male is placed in the spawning ground, and only after two or three hours is the female added to it. The aquarium should be in the shade, and at the beginning of the next day it needs to be highlighted. A nylon mesh is placed at the bottom of the spawning tank with cells wide enough for the eggs to pass through them, but too narrow for the fish itself to reach it. Spawning does not always occur on the same day, sometimes it may not begin for several days. To speed up the onset in such cases, the fish are fed with bloodworms.

One female spawns from 500 to 2,000 eggs in several steps, the process lasts for hours. Until it ends, the fish do not touch the caviar, but after the end they can try to eat it. Therefore, when spawning is completed, they are immediately planted back. In the spawning area, the water level should be lowered to 10-12 cm. From spawning to the appearance of larvae, a day and a half pass, the larvae at first simply hang on plants or glass. They develop very quickly, 4-5 days are enough for them to turn into fry, that is, to begin to swim freely.

Only then can they be fed. They are given infusoria, brine shrimp nauplii and special feed. At first, the food should be very small, and it should be given in small portions. Over time, portions should be increased, enlarging the food itself. The fry can eat each other. To prevent this from happening, it is advisable to sort them by size and seat them in different aquariums. The fish become sexually mature after they have passed for six months, sometimes only by 9-10 months. They can breed until reaching the age of 2-2.5 years, live 3.5-5 years.

Natural enemies of thorns

Photo: What a thorn looks like

Photo: What a thorn looks like

Enemies in nature near thorns are common for small fish: it is a larger predatory fish and a bird. Although for the most part thorns live in small reservoirs, where large fish are not so often, but still sometimes they can visit just for prey. In such cases, the thorns can only flee.

But the rest of the time they themselves often turn out to be the main predators, because other inhabitants of the small rivers where they live are even smaller. In such cases, birds become their main enemies, because it is not so difficult for them to pull a small fish out of a shallow river, and it will not work to hide from feathered predators near the blackthorn.

Large rodents and felines can also pose a danger to it who can sometimes try to catch a fish, because the blackthorn often keeps in shallow water near the shore.

People do not bother them much: thorns are successfully bred in aquariums, and therefore they hardly catch new ones, especially since these fish are cheap. They live in underdeveloped areas in the dense jungles of the Amazon, so that human activity has almost no effect on them yet.

They are relatively less susceptible to diseases, and this is another plus of keeping them in an aquarium. Still, problems are possible: they can become infected with a fungal infection, which will be indicated by a white coating on the body. If an infection occurs, the diseased fish should be removed and treated, as well as the aquarium should be disinfected.

Population and species status

Green thorn photo

Green thorn photo

The range of thorns has remained almost unchanged since their discovery, it has even expanded slightly due to the introduction of this fish by humans into reservoirs adjacent to its habitats. No disturbing signs have been found, the nature in those rivers where this species lives has so far almost not suffered damage from human activity, so nothing threatens the thorns.

There is no exact data regarding their total number, no calculations are underway. However, everything seems to be staying at the same level, or even growing. Although the range of thorns is not very large, and they live only on one continent, those territories in which they are inhabited are very dense.

In the basins of the large tributaries of the Amazon and the Paraguay River, this fish is one of the most widespread, and can be found everywhere. Among small fish, this species can become dominant and displace others from better areas. They reproduce quickly, so the flocks sometimes have to split, some go in search of another pool.

Fun fact: It is advisable to keep them in the dark, otherwise they will fade much faster than usual . This applies to both natural-colored thorns – from dark ones they gradually become more and more pale gray in the light, and bright ones – they will quickly turn pale. Their color fades due to stress, for example, transportation or transplantation, in which case its brightness can recover over time.

Turnetia is a frequent choice for aquariums, because this fish combines beauty and durability, so it is quite easy to keep it, and even inexperienced aquarium owners can safely start it. In addition, she gets along well with many other species, so you can keep her in the general aquarium – but you need to start a whole flock and allocate more space.

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