Is the depression at the bottom of the river the favorite habitat for fish?

That's absolutely right! **The depressions at the bottom of a river (often called "holes" or "pools") are indeed one of the core spots where fish love to congregate, especially in rivers.**

We can think of a riverbed depression as a "five-star home" or a "highway service station" for fish underwater. It's so popular because it simultaneously provides several key elements necessary for fish survival and activity:

### Why Are Depressions Ideal Habitats for Fish?

1.  **Excellent Shelter**

   *   **Shelter from Current:** Depressions are located on the riverbed. When water flows over them, it creates upwellings or eddies, resulting in a relatively slower current. Fish don't need to constantly fight against the rapids, which saves a tremendous amount of energy.

   *   **Protection from Predators:** The deeper water provides natural cover, making fish less visible to birds from above (like kingfishers, cormorants) and predators on the shore.

   *   **Shelter from Harsh Weather:** In hot summers, the deep water is cooler; in cold winters, the water temperature is more stable and warmer.

2.  **Abundant Food Source**

   *   **"Natural Cafeteria":** The current carries various foods from upstream, such as insects, larvae, decaying plant matter, and small shrimp. When the flow hits a depression, it slows down, allowing these food items to settle at the bottom, creating a natural "food collection area."

   *   **Ambush Points:** For predatory fish (like Mandarin fish, catfish, culter), they can lie in wait at the edges of the hole or near structures, using their camouflage to ambush small fish and shrimp brought by the current.

3.  **Ideal Water Conditions**

   *   **Moderate Oxygen Levels:** While fast-flowing areas have the highest dissolved oxygen, fish can't stay there constantly without expending too much energy. The water flowing above the depression brings sufficient oxygen, while the inside of the hole has a gentler flow, creating a well-oxygenated "resting area" suitable for prolonged stays.

   *   **Stable Environment:** The water temperature and quality in deep areas change less, providing a more stable and secure environment for fish.

### Preferences Vary Slightly by Fish Species

Although depressions are gathering spots for fish, different species have slightly different preferences within them:

*   **Bottom-Dwelling Fish:** Such as carp, catfish, yellow catfish, and black carp, prefer the very bottom of the hole, foraging directly in the silt.

*   **Mid to Lower Water Ambush Predators:** Such as Mandarin fish and perch, prefer the **edges or slopes of the hole**, or areas within the hole with large structures (like sunken logs, rocks), which helps them hide and launch attacks.

*   **Cruising Fish:** Such as grass carp, bream, and culter, may cruise above or around the hole, using it as a core reference point and resting station, entering occasionally to rest or forage around its perimeter.

### Besides Depressions, What Other Good Spots Are There?

A perfect fishing spot or fish congregation area is often a combination of multiple favorable features. Besides depressions, you should also look for:

*   **Points:** Prominent areas jutting into the water, which are natural pathways for cruising fish.

*   **Weed Beds:** Provide oxygen, food, and cover.

*   **Inflows:** Bring in fresh water and food, and have high oxygen levels.

*   **Under Trees or Near Structures:** Provide shade and often have falling insects.

*   **Under Steep Drop-offs:** Similar in principle to depressions, providing a safe zone at the deep-shallow water interface.

### Summary

**Riverbed depressions are absolutely one of the favorite habitats for fish.** They combine the advantages of **safety, energy conservation, abundant food, and a stable environment**, making them "strategic locations" for survival in a river. For anglers, finding such a spot is like finding a "honey hole," significantly increasing the chances of success.