Urban Fish? Species That Live In Streams And Rivers In Big Cities

You often don’t realize it, but that polluted waterway in your city can be home to some hardy fish species.

Urban Fish? Species That Live In Streams And Rivers In Big Cities
Urban Fish? Species That Live In Streams And Rivers In Big Cities

There are countless species that live in streams and rivers in big cities and we often drive by with our cars and we don’t even imagine that this can be possible.

Why are there fish in some polluted streams and rivers in cities?

You may think that these fish are there because they were introduced, or because it has always been their natural habitat, however this is not always the case. As in most cities, the smaller streams can be connected to the larger rivers, and that’s where the fish can come from. It may even be that some streams were in the past, unpolluted streams and full of fish, but being a big city, there are hardly any watercourses clean enough to still have native species.

But after all, what species of “urban fish” might be living in the rivers and streams of my city?

There are many species variations according to the region, however some are quite common in most cities. Check it out below:

1. shellfish

The Cascudo is one of the most common fish to be found in streams, streams and urban rivers, due to its immense capacity to live in more polluted, muddy and low-oxygen waters. This fish feeds on the muddy bottom of these streams, and even when there are periods of very low water level, it remains there, firm and strong. Cases of capture of this fish have already been recorded in several places within cities.

2. Tilapia

It is not news that Tilapia is a fish that is very resistant to different conditions of climate and ecosystem, but know that this African fish popular in Brazilian fish farming is also very resistant to urban, muddy and polluted waters. Some species of Tilapia, such as Blue Tilapia for example, can withstand even waters with high salinity, that is, from rivers that are connected to the sea.

In 2020, a school of Tilapias was seen breeding in Arroio Dilúvio in Porto Alegre. The stream is extremely polluted and the fact that these fish are there, with nests, shows their ability to adapt to extreme conditions of pollution and low oxygenation of the water. **

3. African Catfish

As the name says, this fish is not native to Brazilian waters, its origin is African, and the species was introduced in Brazil. On the Tietê River, in São Paulo, one of the most polluted, if not the most polluted river in the country, is home to this species that lives in the midst of sewage residues, chemical products and low oxygenation of the water.

For this fish, the most acceptable explanation is related to its breathing made by a kind of lung, which makes this fish go up to the surface from time to time to breathe. See below a video that shows this unexpected case of life in Tietê.

4. Mullet

Mullet is another species of fish that can be found in polluted rivers and streams and be called an “urban fish”, especially in coastal cities, however, they have already been seen in Porto Alegre

Mullet feeds on nutrients present in the water, and it is likely that the organic sludge from the Flood is what attracted these fish into the city.

Final considerations

Did you see how many “urban fish” live in streams and rivers out there? Imagine if our rulers practiced sustainable policies and these places were depolluted? Many other species could live freely and turn these waterways into true natural estuaries. Who knows, maybe one day?

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