How deep can perch feed by sight?
The limit is set by light penetration, not by the fish. In clear Great Lakes water, schools sight-graze on flats of 10 m (33 ft) and deeper at midday; in a stained kettle lake, useful light may quit at 3–4 m (10–13 ft). The fish itself inspects food from only about half a meter (a foot or two) away, so what water clarity really controls is which depths carry enough light for that close-range inspection during the day. That is why the same lake fishes deeper on bright days and shallower under heavy overcast.
The full story
This answer is one piece of a longer lesson — setups, diagrams and the reasoning behind it.
More questions about Vision
Same topic, other species
- Do black crappie and white crappie prefer different water? — Crappie
- Does braided line spook largemouth? — Largemouth Bass
- What are the best light windows for muskie? — Muskellunge (Muskie)
- Do pike hunt by sight at night? — Northern Pike
- Fluorocarbon or braid for smallmouth? — Smallmouth Bass
- Can trout on a stream actually see me standing on the bank? — Trout (Rainbow · Brook · Lake)
- Does moon phase matter for walleye? — Walleye