Hippopotamus defecating in the water is actually a way to spread the virus. These feces will produce a lot of bacteria. Moreover, hippos eat a lot, so the weight of defecation is also great. Then there are many bacteria in so much feces, which will consume oxygen in the water, so other animals in the river can't breathe, and fish and shrimp will die of lack of oxygen.
In addition, there are a lot of methane and hydrogen sulfide in hippopotamus feces, which will cause poisoning and suffocation of animals in rivers. In fact, there are these substances in the feces of every animal, but hippos are too heavy and have too much feces. Thousands of hippopotamus defecation is likely to cause thousands of fish and shrimp to die.
The naive appearance of hippopotamus is actually an illusion, because hippopotamus is actually a very fierce animal. And it is an omnivore, not only eating grass, but also eating meat. Hippos have meat to eat. They can eat crocodiles, buffaloes and water snakes. Hippos can eat grass when there is no meat, and they are often fed grass and watermelon in the zoo.
A hippopotamus can weigh up to three tons in adulthood. It is a very huge animal, which can even compete with fierce animals such as tigers and lions, and can also defeat tigers. This is enough to see the ferocity of hippos. If hundreds of hippos gather together, even lions and tigers may not dare to approach easily.
Moreover, even in the return of whales, the excrement is still limited. But because hippos eat a lot of grass and food, they have to excrete too much feces every day. So much feces poured into the river at once, all the oxygen in the water was consumed at once, while those animals who could only breathe in the water were suffocated by lack of oxygen.