# GDFF vs Erchang Fish

The clearest difference is review sentiment: Erchang Fish at 33% against GDFF's 0%. GDFF's advantage is update cadence (every 3 weeks vs every 7 months). On price, ads, in-app purchases and monetization model there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

GDFF ships an update every 3 weeks, Erchang Fish every 7 months. The most recent releases landed on October 7, 2026 and October 14, 2026 respectively.

## The numbers

| Metric | GDFF | Erchang Fish |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | 0.0% of reviews | **33.3% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 3 weeks** | Every 7 months |
| Monetization | Free | Free |
| Size | 41 MB | 68 MB |
| Requires iOS | 10.0 | **9.3** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [松林 赵](https://appshunter.io/developer/596658260) | [定敢 刘](https://appshunter.io/developer/1194376703) |

## What reviewers say

### GDFF

[App page](https://appshunter.io/ios/app/gdff/id1468415725)

This professional-grade sonar device connects to your smartphone to provide real-time underwater data. It maps depth, temperature, terrain, and fish density up to 500 meters away and 40 meters deep.

**Highlights:** Real-time sonar technology, Underwater mapping (depth, temp, terrain), Fish density and size detection, 500m signal range, 40m maximum depth, Adjustable gain and multiple modes

**Features:** macOS Compatibility

**In-app purchases:** none


### Erchang Fish

[App page](https://appshunter.io/ios/app/erchang-fish/id1605890664)

This intelligent fish detector app offers a dual-band sonar system with a user-friendly interface. It's designed to be a helpful tool for fishing enthusiasts, providing convenient operation for better angling experiences.

**Highlights:** Dual band intelligent fish detection, Friendly interface, Convenient operation, Fishing helper tool

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is GDFF free?

GDFF is free to download, with no in-app purchases.

### Is Erchang Fish free?

Erchang Fish is free to download, with no in-app purchases.

### Do GDFF or Erchang Fish have ads?

Neither GDFF nor Erchang Fish shows ads.

### Which is updated more often, GDFF or Erchang Fish?

GDFF ships an update every 3 weeks, and Erchang Fish every 7 months. Most recently, GDFF was updated on October 7, 2026 and Erchang Fish on October 14, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*