Pirá-Brasília: annual fish
This fish species was discovered when Brasilia was being built. That is when the red dirt dug from the soil for the construction works would stand out in the midst of the Cerrado’s green savannas in the Central Plateau region. The tiny fish was found in the marsh areas close to Riacho Fundo streamlet, a tributary to the Paranoá Lake. The location now shelters the Zoological Garden.
Pirá-Brasília inhabits shallow lagoons which are created once a year during the rainy season. Those lagoons dry out during the dry season -- and this dry season is long and well marked in Brasília. When the lagoons dry out, the tiny fish die. Nevertheless, they leave something behind them, something hidden underneath the earth which will ensure its come back as soon as it starts to rain again.
How did these tiny fish get here?
Before they die, Pirá-Brasília fish lay their eggs in the lagoon soil. The work is shared between the male and the female. The eggs remain underneath the dry soil and wait for the rainfall – the eggs remain in a state called Diapause. When the rain starts falling again, the contact with water causes the eggs to hatch. The fingerlings develop quickly, for the Pirá-Brasília life cycle is very short.
In about two months the Pirá-Brasília fish reach maturity. Someone who is unaware of this and finds the tiny fish in one of those just formed lagoons can raise the question “how did the fish get here?”
But now you know: Pirá-Brasília fish do not fall from the sky, they sprout from the earth!
Red with silver dots
Male and female are quite different in this species.
The female Pirá-Brasilia measures around two centimeters, it is light brown color with one or two black dots on the body. One can almost see through the transparent fins.
The male Pirá-Brasilia measures around 2.5 centimeters and is much more ornate than its female counterpart. The male color is red with metallic blue streaks and dots all over the body, including the fins.
These fish feed on small insects, some algae and even vegetables.
Why are they threatened?
Pirá-Brasília is a Federal District endemic specie, i.e., it only exists in this place. The lagoons inhabited by those tiny fish are formed amidst the Buriti palm (Mauritia flexuosa) pathways or in the marshlands near gallery forests.
The urban and population growth in the Federal District is a threat to the forests within which lagoons are created and shelter the Pirá-Brasília fish. The river and lagoon siltation caused by deforestation and pollution is the main threat to this species. If the lagoons are not recreated when the rain falls, then the eggs deposited before the drought will not hatch and the Pirá-Brasilia risks disappearing.
To make the situation worse, besides the fact that forests are being polluted or converted into urban and agricultural lands, Pirá-Brasília’s beauty attracts ornamental fish farmers. The aquarium suppliers have overfished this tiny fish to such an extent that it is almost gone.
Therefore, this species appears in the IUCN’s and the Brazilian Ministry of the Environment’s lists of threatened animals.
Today, Pirá-Brasilia is only found in the IBGE Ecological Reserve, which is a protected area within the Gama - Cabeça de Veado Environmental Protection Area’s wildlife area.
Watch the video which shows the Pirá-Brasilia fish burying their eggs in the soil. http://chc.cienciahoje.uol.com.br/revista/revista-chc-2009/201/galeria-de-bichos-ameacados-pira-brasilia