Which river has the most species of fish?

It's difficult to definitively say which river has the most species of fish, as the data can be tricky to collect and compare across different regions. However, some contenders for the title include:

* The Amazon River: This massive South American river is known for its incredible biodiversity, with estimates suggesting it could have over 3,000 species of fish, making it a strong contender.

* The Congo River: Another major African river, the Congo is also extremely diverse, with estimates of over 1,000 species of fish.

* The Yangtze River: This river in China is the longest in Asia, and although it has been heavily impacted by human activity, it still boasts a diverse fish fauna.

It's important to note that:

* Data is often incomplete: Comprehensive surveys of fish species in rivers are challenging and expensive, meaning the actual number of species in each river could be even higher.

* Definitions can vary: Some rivers may be considered part of larger systems (like the Amazon Basin) making it difficult to isolate the river's specific count.

* Environmental factors: Climate change, pollution, and habitat destruction can all impact fish populations, leading to changes in species numbers over time.

Ultimately, the answer to which river has the most species of fish is a complex one with no definitive answer. However, the Amazon, Congo, and Yangtze are strong contenders based on available data.