▷ Pez Monja, Black tetra Guide 【】 And Care At Aquarium

▷ Pez Monja, Gymnocorymbus Ternetzi【 Guía Y Cuidados En Acuario 】

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Monja fish or fish Monjita

  • Scientific name: Gymnocorymbus Ternetzi
  • Common name: fish nun, pez monjita, black tetra, black widow
  • Size of the aquarium: forty a 80 liters
  • Temperament: peaceful, fast and awake
  • Temperature: Between 20 and 26 ° C
  • pH: Neutral, 7
  • Diet: omnivores
  • Length: Males up 7,5 cms. and females only 5 cms.


The fish Gymnocorymbus Ternetzi, better known as nun fish, It is a specimen from the family Characidae (characids). This animal is highly sought after by those interested in aquariums, as It has an attractive color, They adapt well to different environments and do not require a very specific pH. Another point in its favor is its behavior in the aquarium. It is a very suitable fish to live in a community tank Amazonian type, where ideally enter a shoal, which will move with speed and agility, generating a great visual appeal.


Monjita this type of fish has a very explicit way, It has a high body shape, thickening half, but at the same time, It is compressed on the sides. His eyes are very large (considering the size of your body), the mouth is positioned downwards and is small. On the other hand, You have what is called a caudal fin short and bilobed, and anal fin, so named for being in the back of the fish, It is long and very large, totally different from the rest of the body. Adipose fin is this type, Nevertheless, through different crosses and selection of specimens, varieties have evolved with other types of fins that are even longer and darker coloration.

The nun fish coloring

In the case of external physical appearance could also say that, unlike others in its class, The black tetra has a special color, since it is not unicolor, but diffuses in various colors. As has a gray background that stays until half, you can see two strips of black shade than vertical, one just behind the eyes and have another strip even wider in the center of the body, that sometimes it occurs in the dorsal fin. Because of its great popularity in the market, the color of the fish nun fantasy has been altered thanks to artificial breeding is done in many laboratories. Groups of blue fish nun, gold, and semi-albino albino. The problem with this kind of animal is that genetic modification can alter their life expectancy, because they can provoke different types of diseases. So you do not buy such case, either because they are not able to enjoy a long time and because there is no need to support this type of practice, It is always better to resort to what comes from nature.

Sexual dimorphism

Sexual dimorphism in the fish nun nun male and female fish, shown in the flap of the male is shown wider in the bottom, very different from the female, which it is more pointed. In addition to this, females can also be of a larger size and thicker, if compared with the male. Thus it is that they can be easily differentiated.

Distribution and habitat

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¿Te want to know where you can get a nun fantasy fish? Surely you did not know, but if you live in the South American continent (as Paraguay and Argentina) You are very close to them. This animal exists in areas that have a really rich and wild vegetation, so it is usual to see them in places like basins, rivers and sides. The most important thing for them is to be a dark place, where illumination does not penetrate much and can hide so efficient, so his shade plays such a vital role for survival.

Aquarium conditions

¿Deseas have a nun fish inside your house? To do this must be informed, as these animals need a good aquarium with capacity of up to eighty liters, where they can feel comfortable, Pure and habitat. What you should consider when buying the aquarium is the following: Do not put many aquatic plants, dark colors chosen for the substrate Y, If you want to adapt faster to the atmosphere, acquires aquarium filter with moderate power to resemble a stream of water. Besides all this, You must also ensure that illumination of the aquarium is not very intense. Among other technical aspects you must remember to create the perfect aquarium for fish nun, the quality of the water has to move within the following parameters:


This is a very important and interesting topic, as This type of fish can not eat the same release, in his life within the aquarium. However, adapts easily all kinds of power options. Thanks to its status omnivorous, eat from worms, live insects or crustaceans and at the same time, You can feed him at home with fish food is frozen that, granules or lyophilized. You see it is very comfortable to keep them alive.

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Behavior and compatibility

Many people consider the nuns as affable and nice, and it is that this fish is really fast and awake. Nevertheless, we must create an environment where you feel unthreatened as, on the contrary, You can behave nervously, but that is achieved with a level of darkness and dim aquarium filter that can create streams. When a fish monjita not feeling well in an aquarium proves standing still, mingling with the environment and hide in vegetation. If you want to give company, also you can do it by creating a shoal of between eight or 10 specimens of its kind. They like being in a group, play chase and not get hurt, so you do not have to worry about anything. With age often be more quiet and less active than in its juvenile stage. Habitually They are not aggressive, except long-finned fish... that usually pursued by the aquarium. Should not be mixed with guppies O scalar, it is best mixed with other fish Tetra.


In relation to reproduction and pregnancy of the nun fish, we can say that usually they breed very regularly. They have great sunsets. Courtship of the male begins chasing females tirelessly, until at a certain time it gives you a little bump and then the female expels certain amount of eggs at a time are fertilized by the male. They can put between 300 Y 400 eggs, in the early hours of the day. It is for this reason that breeding aquarium should be about 50 liters. Eggs can take between 18 a 26 hours to hatch and, Once they born, you must fry feeding first infusoria Y, when time has passed, you can try with brine shrimp. It is important to always follow them and see how they develop.

Cleaner background for the aquarium
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Photos of the nun fish

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