Skip to content
ENGLISH EDITION · English fishing guide
The Fish Finders

DEEPER TIPS · FISH ARCHES & BOTTOM

Why doesn’t the absence of a fish arch on a Deeper mean “no fish”?

Short answer: Because sonar shows only a small area beneath its transducer cone. Fish may be holding on the bottom, off to the side outside the cone, or may not produce a distinct echo. So read the bottom, structure, and transitions first—the fish arch is only an additional clue.
Original image illustrating Deeper sonar interpretation and hotspots
Original image and video from the previous article: Read the structure first, then assess possible fish signals.

This existing URL is intentionally being retained. It answers a different, very specific question than our comprehensive guide to Deeper images and hotspots: What does it mean when you see no distinct fish arch?

Table of ContentsHow Does a Fish Arch Form?Why Is the Bottom Often More Important?What Can a Hard or Soft Bottom Reveal?When Does Structure Become a Fishing Spot?How Do You Verify the Image on the Water?

How does a fish arch form on a Deeper fish finder?

Short answer: An arch forms when the fish and transducer cone move relative to each other. Its shape depends on the cone, depth, retrieve speed, angle, and settings. An arch is therefore not a measure of size or a guarantee of a catch.

A Deeper does not record the underwater world like a camera. It processes echoes. As the transducer passes a fish, the distance to the fish may first decrease and then increase again—creating an arch. If the fish is holding directly on the bottom, its echo often barely separates from the bottom line. If it is off to the side, it may be completely outside the cone. And a fish icon is an interpretation made by the app, not the fish itself.

Why is the bottom often the more useful information on a Deeper?

Short answer: Because the bottom shows you where something changes: a drop-off, ledge, plateau, rock, vegetation, or transition. These structures are more likely to remain in place than an individual fish and help you narrow the search area for your target species.

The previous article already made the right point: A strong bottom echo can indicate dense or hard substrate, while a change in the line can indicate a drop-off or irregularity. That is not enough to say, “Fish are definitely here.” But it is a solid starting point for the next question: Why might this area provide food, cover, oxygen, or a travel route today?

What can the difference between hard and soft bottom tell you?

Short answer: It can reveal a transition that may interest fish. However, always verify whether an echo really represents rock, gravel, mud, or dense vegetation through repeated casts and by assessing conditions on the water.

In a lake, a hard area may be a mussel bed, gravel flat, or rocky structure. A soft transition may indicate mud, loose material, or vegetation. For carp, a feeding route along such a transition may be productive; for predators, the edge between two areas may serve as a hunting route. These are hypotheses—not an automatic formula for catching fish.

When does structure become a genuine hotspot?

Short answer: When the structure and current conditions suit your target species. A drop-off becomes interesting only when the depth, season, light, current, prey, and your fishing plan also align.

Check a promising spot from two directions. Mark it. Then deliberately decide whether to fish above, below, or along the drop-off. For perch, prey and an edge leading to open water may be crucial. For zander in a river, the transition between current and slack water may matter more. For pike, it may be the connection between vegetation and shallow water. For carp, a route or plateau. The Deeper shows you the area; finding fish starts with interpreting it correctly.

How do you properly verify a Deeper image on the water?

Short answer: Repeat the scan from a second angle, keep your retrieve speed constant, and then change only one part of your fishing plan. This helps you determine whether the structure is real and how it relates to fish behavior.
  1. First, look for a notable change in the bottom.
  2. Verify it with a second cast.
  3. Record the depth, water level, weather, and possible prey.
  4. Make your first cast along the most plausible route—not blindly at an icon.

Video in German — English version coming soon

The original message and video from the previous version of this article remain: Fish arches are not everything. Clear answers, a distinction from the hotspot guide, and a practical process for applying this information on the water have now been added.