Fish finder readings

[Snakemover]

I've been learning how to read my depth finder to find structure, depth changes and other places like likely to hold fish and I've seem some things that I can't figure out what they are.

Sometimes when I'm trolling around slow, looking for structure and depth changes, I'll see what looks like several fish arches stacked right on top of each other. There could be as many as ten of them. I see them at different depths down to 25 feet. Can someone tell me what those might be?

Also, when I'm stopped, or just drifting real slow, I'll see what looks like angled lines across the screen. Like something changed depth while in the radar cone. The lines can be thick or thin sometimes and can go all the way to the bottom. What causes those lines.

Thanks in advance for any help.

Dennis

[Randall]

Fish that are stacked vertical on top of each other are usually crappie in most lakes I fish. The lines you are seeing are most likely fish that are going down toward the bottom as you ride over but no way of knowing for sure. Bubbles from decomposing matter on the bottom will make a streak on the screen running from top to bottom sometimes as well. Keep in mind that most fish dont appear as arches but as dots, dashes and lines.

[Guest ouachitabassangler]

I agree. But there are other possibilities. The stacked arches are often moss covered tree branches. This time of year bass don't stack up from deep to shallow, definitely not below a thermocline. If you see those arches below a horizontal band splitting the screen (thermocline layer), it's not stacked fish.

You must be moving at troll speed to pick up fish arches. When still anything below you moving will appear as lines. A line growing from lower depth to higher depth at about 45 degrees slanted right is a fish swimming up inside the sonar cone. Sometimes you see the line curl back down. That could be a bass rising to check your bait out then breaking off when disinterested, seeing the boat or hearing a noise from inside the boat. Multiple lines streaming across the screen could be a school of fish swimming through. Once the boat is moving you won't wee those lines, but instead arches. Bass don't stick around long for a good photo op when moving slowly over them, especially when your boat casts a shadow on them, so seeing textbook perfect arches is fairly rare. You'll see more of those, or partial arches, at higher trolling or outboard speeds. The faster you travel the more a fish "arch" appears as a fingernail slice standing on end, IOW, half an arch. Perfect arches are possible for a fish dead center in the sonar cone. Fish out from center appear as slices, more banana shaped.

Jim