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.

Introduction

For carp anglers, especially those who fish at night or in challenging conditions, bite alarms are an essential part of the setup. With so many brands on the market, choosing the right one can be overwhelming. Recently, NDS (ND Sonar) introduced the K15 bite alarm, a model designed with smart sensitivity, long wireless range, and multi-device sync features.

In this article, we’ll compare the NDS K15 against leading competitors like Fox, Delkim, and Sonik, analyzing performance across multiple dimensions to help you decide which alarm best fits your fishing style and budget.

NDS K15 Bite Alarm – Key Features

Based on the official NDS product page, the K15 offers:

The NDS K15 is positioned as a modern, smart alarm that combines traditional reliability with innovative features.

Comparison Dimensions

We’ll compare across these key factors:

1. Sensitivity & Accuracy
2. Alarm Tone & Sound Options
3. Wireless Range & Remote Control
4. LED Visibility & Night Features
5. Anti-Interference & False Bite Control
6. Durability, Waterproofing & Warranty
7. Value for Money & User Trust

NDS K15 vs Fox Bite Alarms

Fox is a household name in carp fishing, with models like the RX+ and Micron series widely used.

• Fox strengths: strong waterproof build, reliable LEDs, multiple tone/volume options, mature ecosystem of accessories, strong brand reputation.
• Fox limitations: sensitivity is good but still mechanical, meaning false beeps may occur in high winds unless well-adjusted.

Summary: If you want proven reliability and a big-brand ecosystem, Fox is safe. If you want innovation, longer range, and a fresh feature set, NDS K15 stands out.

NDS K15 vs Delkim Bite Alarms

Delkim has long dominated the high-end market with its vibration-based detection system (no roller wheel needed). The flagship TXi-D is still a benchmark.

• Delkim strengths: vibration sensing = ultra-sensitive, LED brightness modes, 24 tone options, anti-theft alarms, rock-solid reliability.
• Delkim limitations: premium pricing, steeper learning curve, no firmware upgrades.

Summary: If you demand ultimate sensitivity and proven pro-level gear, Delkim is king. If you want modern smart features and long-term firmware support, NDS K15 offers more for less.

NDS K15 vs Sonik Bite Alarms

Sonik is a mid-range player with alarms like the HEROX and Gizmo series, popular for affordability.

• Sonik strengths: budget-friendly, 8 sensitivity levels, multiple tones, bivvy light sync, drop-back indication, ~150m wireless range.
• Sonik limitations: shorter range, less advanced filtering, shorter warranty.

Summary: Sonik is perfect if you’re budget-conscious or just starting out. NDS is ideal if you want longer range, stronger durability, and advanced filtering without going full Delkim.

Final Verdict – Which Bite Alarm Should You Buy?

There is no single “best” bite alarm — only the one that fits your style, conditions, and budget.

• Choose NDS K15 if you want innovation, long wireless range, smart sensitivity, and future-proof firmware upgrades.
• Choose Fox if you want brand reliability, proven systems, and accessory support.
• Choose Delkim if you demand ultimate sensitivity and premium pro-level gear.
• Choose Sonik if you’re budget-minded but still want solid performance.

Buyer Tips:

• Big waters / long range? → NDS K15.
• Night fishing / LED visibility important? → Both NDS & Delkim strong choices.
• On a budget? → Sonik.
• Want pro-trusted gear? → Delkim or Fox.
• Future-proof investment? → NDS, thanks to free firmware upgrades.

Preparation:

Download the latest version of NDS fish finder APP 2.0.0

https://apps.apple.com/gb/app/nds-fish-finder/id6745814231

https://play.google.com/store/apps/details?id=com.nds&hl=en

Firmware Update:

*Spot-Lock: Upon reaching the designated spot, the bait boat will lock within a 1-meter range. If the boat drifts beyond this range due to water currents, it will automatically return to the spot until the user triggers the joystick press operation.

*Low Voltage Return-to-Home (LV RTH): When the boat's battery voltage drops below 14V, it will automatically initiate the return-to-home operation.

*Spot Slowdown: When the boat approaches within 1 meter of the target spot, it will automatically reduce its speed.

Improved GPS Accuracy: Enhanced GPS positioning precision for better accuracy.

Adjustable Speed: After the firmware upgrade, the cruising speed can be controlled via the APP with 10 adjustable levels. To avoid user confusion, the boat will automatically revert to the highest speed mode after reboot.

Stealth Mode: Press and hold C + D to activate stealth mode, where all lights and beep prompts will be turned off. The boat will return to standard mode after reboot.

Hold Press for Constant Speed: Push and hold the joystick forward for 5 seconds to enter constant-speed cruise mode, which remains active until the user presses the joystick down.

Note:

1. Despite the new firmware upgrade, features marked with * require an Autopilot subscription to be activated.

2. After all modules are successfully upgraded, please re-pair the handset with bait boat

3. Please restart the APP, handset, bait boat after the upgrade is completed.

If you have any questions:

1. You can watch the video guide.

https://www.youtube.com/watch?v=3AirWczdxjE

2. You can also join the NDS fanbase group

https://chat.whatsapp.com/D9agFzsUlt1CbVqvR1DMWY

Key Upgrade Highlights:

1. *Effortless Spot Definition via Sonar* Set spots with a double-click directly on the live/replay sonar display.  

2. *Automated Path Optimization for Bathymetric Mapping*

  - Streamlined workflow for efficient bathymetric chart generation.  

3. *Enhanced Shallow-Water Detection Accuracy*

  - Minimum detection precision improved to **0.5 cm**.  

4. *NDS Cloud Integration for Bathymetric Data*

  - Upload sonar data to visualize and analyze lake/river bathymetry via web browsers.  

5. *Rotatable Offline/Satellite Maps*

  - Support for two-finger map rotation, enhancing intuitive mapping operations.  

6. *Quick Connection Button*

  - Simplified device pairing with one-touch connectivity.  

7. *Multi-Unit Measurement Support*

  - Added units: *Meters, Feet, Yards, 12ft Rod*.  

8. *Improved Real-Time Positioning Accuracy*

  - Enhanced precision for mobile live markers.  

9. *Screenshot & Share Functionality*

  - Capture and instantly share mapping results.  

10. *Active Group Command Optimization*  

   - Execute multiple actions simultaneously with a single click.  

11. *Hardware-Free Autopilot Activation*

   - Enable autopilot online—no hardware modifications, eliminating installation risks.  

12. *Firmware Upgrade for Extended Range & GPS Precision*  

   - Optimized for NDS Sonar & NDS WiFi Extender:  

     - Extended communication range.  

     - Improved GPS positioning accuracy.

1. Improved map location accuracy.

2. Rotatable map.

3. Fixed known issues.

Firmware Update Content:

1. Adjust motor operating frequency to ensure compatibility with the NDS sonar.
2. Optimize GPS signal reception to minimize signal loss.
3. Enhance the Handset’s 2.4G channel for seamless integration with the NDS Wi-Fi extender, reducing interference and extending communication range.
4. After all modules are successfully upgraded, re-pair the Handset and Bait Boat.

Note:

• Restart the APP, Handset, and Bait Boat after completing the upgrade.

Download the ZIP file and locate a local 3D printing workshop to print your NDS door. We'll also launch NDS door accessories soon.

NDS Sonar Firmware v1.1.4 Key Updates:

1. Transducer Transmission OptimizationEnhanced acoustic emission efficiency and signal stability
2. Over-the-Air (OTA) Performance EnhancementImproved firmware update success rate and data transfer reliability
   Donwload NDS Fish finder APP 1.5.3 to upgrade Your NDS Sonar firmware.

We are pleased to announce that from today you are able to pre-order the built-in sonar kit l.

The price for the NDS build-in Sonar kit including fitting by one of our workshops:

Workshop sonar installation £599 (for existing boats wishing to add sonar built-in)

Visit this link to select a retailer and complete your order: https://ndsonar.co.uk/uk/product-detail-24

1. Optimize user experience: Modified menu layout.

2. Fixed the bug that caused action groups to be deleted upon logout.

3. Optimized Fish Finder algorithm.

4. Fixed known bugs.