Blackline penguinfish

Aquarium fish: Blackline penguinfish (Thayeria boehlkei)
Size: 6 – 7.5 cm
Origin: South America
Water temperature: 22-28 ° C
Aquarium volume: 70 l

Blackline penguinfish (Thayeria boehlkei ) – a popular, characteristically swimming aquarium fish from the tetras family.


The species is native to South America . Occurrence probably limited to the upper Amazon basin in Peru and Aragua in Brazil. Found in a variety of environments. From wetlands with lush underwater vegetation to jungle streams.

Characteristics and disposition

Reaches about 7 cm in length. These fish usually swim diagonally with their heads up. Gender difficult to distinguish . The females during the spawning period are usually slightly more rounded than the males. Color olive silver.

At first glance, the Blackline penguinfish is easily confused with a short spine hockey game , in which the black stripe along the body begins at the lower caudal flap, runs further in an arc and ends at the height of the rear edge of the dorsal fin, while in the Amazon hockey player it runs along the entire body up to the edge of the gill covers. They are a shoal species and they feel better in a larger group. 6 pieces are recommended for the aquarium, preferably 10 or more. They are considered to be fish that nibble at the fins of other fish. This behavior is not that noticeable when kept in larger amounts.

Like most tetras in the school, they also look nicer.

Nutrition and feeding

In nature , a micro-predator , it feeds on insects, worms, crustaceans and other small invertebrates. In an aquarium, it accepts almost any food. The best condition and coloration, however, will be ensured by regular feeding of live and frozen foods, eg Daphnia, Artemia, insect larvae.


These fish are the perfect addition to densely overgrown tanks.

The aquarium can be decorated with twisted roots, branches, smooth boulders and stones. Dark soil and floating plants will also be a good choice, providing some shade for the fish. River gravel, bough and twisted roots will be needed to map the natural habitat of the South American jungle stream. It will be complemented by dried Oak, Beech or Ketapang leaves. Wood and leaves should give the water the color of weak tea.

A peat filter cartridge can also be used for this purpose. In such an aquarium, not too bright light is recommended and the plants will not (like in nature) grow too well. You can add shade plants such as Java moss, Mikrozorium pteroptus, Anubias or Zwartka . Of course, they do not fit this biotope, but they can be added to liven up the tank a bit. They easily adapt to various conditions .

They feel equally well in soft and acidic water as well as in more alkaline and hard water from the pH range of 5.5 – 8.0. They will not feel comfortable around moving and larger fish. Ideally, other species from South America will be ideal mates, such as Taurus, Harlequin , Microbes ( Beckford ‘s girdle ), Cichlids and other small cichlids. Kiryski , Zbrojniki. In general aquariums they can be combined with smaller Razbors , Brzanki, labyrinth fish or Barwniaki .


Reproduction is fairly easy , but an additional aquarium will be necessary for this purpose. A tank with dimensions of 45x25x25 cm will be sufficient. In it, we place clumps of small-leaved plants, e.g. Java moss or an artificial aquarium mop. The bottom can be covered with a mesh with fine meshes.

Water chemistry is not very important for this species, but better results are obtained with acidic or neutral water at a slightly higher temperature. A small sponge filter is sufficient for filtration. Hockey players can be bred in a larger group of 6 fish of each sex. Fish carmine abundantly with live food and reproduction should not be a problem. However, it is more effective to reproduce in pairs.

We separate males from females and feed them with live food for several days. When the females are noticeably larger around the abdomen and the males are more intensely colored, we choose the thickest female and the most beautiful male and transfer them to the breeding aquarium in the evening. Spawning usually takes place in the morning of the next day. Fish can lay up to 3,000 eggs, but usually there are about 1,000. Males during spawning release so much dandelion that sometimes a water change may be needed.

Parents eat their eggs and fry whenever they have the opportunity, so we catch the adult fish as soon as we spot the eggs. Hatching occurs after 12-24 hours. After another 3-4 days, the larvae begin to swim freely. In the first days, we give micro foods until they are large enough to take micro nematodes, Artemia or insect larvae. Roe and fry in the first days are sensitive to light.


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