The "Penguin Tetra" is actually two related species, "Thayeria boehlkei" and "Thayeria obliqua".
The easily seen differences between these species are quite small. Both species have a tendency to swim in a tail down position, but this is
more pronounced in Thayeria obliqua. Thayeria obliqua has a shorter black line than Thayeria boehlkei, and Thayeria obliqua grows a little bigger although these are both small fish. The species most often available in aquarium shops is Thayeria boehlkei.Some people prefer to keep the name "Penguin Tetra" for Thayeria obliqua and call Thayeria boehlkei
the "False Penguin Tetra". There are several other common names for
this fish, some of them, like "Penguinfish", Penguin Fish", etc are
also based on its perceived resemblance to a penguin, while others like
"Short Striped Thayeria" do not. In Australia, it is often sold as a
"Hockey Stick Tetra". Certainly the shape of the prominent black line
is reminiscent of the shape of a hockey stick.
Thayeria boehlkei grows to about one and a half inches (4cm) long while Thayeria obliqua
can get a little bit bigger. They come from the Amazon River and its
tributaries in Brazil and Peru, preferring slow moving stretches with a
lot of plants.
Water conditions
The PenguinTetra is a tropical fish. 24̊ C (75̊ F) is a suitable
temperature to set your thermostat. The water they are used to in the
wild is soft and acid, but in captivity they will adjust to neutral pH
and some hardness.
The PenguinTetra does better in clean water
and care needs to be taken with the water quality. They are sensitive
to Ammonia, Nitrite and excessive concentrations of Nitrate.
Food
Like
many tetras, the PenguinTetra is an easily fed omnivore. It will eat
all normal aquarium foods, but will enjoy some live food like mosquito
larvae and Daphnia. Frozen foods, including frozen blood worms are also
appreciated.
Companions
The PenguinTetra
is a
peaceful schooling fish. I suggest a minimum of four, and preferable
more be kept together. They can be kept with most small, reasonable
peaceful fish, including: Red Eye Tetras, Cardinal Tetras,
Silvertip Tetras, Gold Barbs, Cherry Barbs, PristellaTetras, Rummy Nose
Tetras,White
Cloud Mountain Minnows, Black Widow Tetras, Rosy Barbs, and Colombian Tetras, as well as Peppered Catfish.
A school of Penguin Tetras can usually even be kept with slow long finned fish like Siamese Fighting Fish, Guppies and Endlers Guppies, although I would not be sure in every case.
Sexing
There
is not much difference between the sexes of the PenguinTetra, but when
in breeding condition, the females get a rounder belly.
Breeding
Thayeria boehlkei
is the PenguinTetra most likely to be available in shops and this fish
is reasonably easy to breed. I suggest a water level lowered to about 6
inches (15cm) acidic and very soft water with a temperature of about
27̊ C (81̊ F). There should be fine leaved, bushy plants in the
breeding tank.
The PenguinTetra is a prolific breeder in the
sense of producing a lot of eggs. A female of this little fish with a
very well rounded belly can produce as many as 3000 eggs. These are
very small. The male produces a large amount of sperm to try to
fertilize all these eggs, and this can contribute to fouling the water.
Partial water changes are recommended to maintain the high quality of water that the fry need. The addition of an aquarium fungicide is
recommended to help protect the eggs from fungus early on.
The eggs should hatch in as little as 12-18 hours. The babies are very small, and need protozoa (infusoria) at first.
Pest Fish
Although the PenguinTetra is a delight in an aquarium, as with all pets, do not
allow them to get into ecosystems they are not native to.
Aquarist
are frequently blamed for this, and there is no doubt that there are
cases of accidental, or deliberate, release of fish by aquarists, but
my own research suggests that the worst culprits for this historically
have been governments and their departments. See Ecological Disasters for some examples.
Fishermen are also not totally blameless; see Lake Eacham Rainbowfish Fact Sheet to see how a species became "extinct" through the introduction of fish from other ecosystems.
Sources
I am grateful to the following sources of information: Data Base,
Aqua World, Fish Profiles.com, Munga Bay, Aquatic Community, Badman's
Tropical Fish and Live aquaria.com.
This fact sheet also appears on the international version of our website at bettatrading.com
Penguin Tetra, Thayeria boehlkei, showing typical tail down attitude in the water.
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