✅ SOLVED Piles of rocks in rivers and streams...

[aquachigger]

Does anyone know what makes these piles of rocks in rivers and streams? I see them all the time when I am detecting and no one can tell me what is making them. Could it be muskrats or mink? They are always completely submerged. How about some sort of fish? Some of the rocks are pretty hefty. I have seen many of them in the big rivers and many in very small streams. They can be several feet tall and 4 feet across. Many are much smaller. It's driving me crazy not being able to figure it out. This is one from a few days ago that was in a small stream.





I can say with certainty they are not man made. Help!

 

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[Pstarkey35]

I'd say fish. Many fish make nests like these and spawn over them. Eggs fall in between the rocks and stay protected.

 

[Jeff H]

Aquachigger, I've seen eddy currents during a high flow leave similar piles of rocks in strange places. They would look very out of place during low flow periods. If it were mink or muskrat, I think probably they would be above water as they would likely be scent marking them. I certainly could go with fish as Pstarkey mentions above. Maybe even a crustacean like a crayfish

 

[aquachigger]

Bingo! It is a fish! Apparently it is a Fallfish (White Chub) spawning bed. I just got lucky with an image search for "spawning bed". They do pile up rocks. I have been trying to figure this out for YEARS! Even the Potomac Riverkeepers couldn't help. Thanks!

SPAWNING.—The spawning period usually occurs in June.
This fish has a peculiar habit of piling up large pebbles, ranging in size from an inch to an inch and a half in diameter,
for a nest. The fish carries the pebbles in its mouth. The nest may be from three to four feet wide and ten or more inches high and is located in the swift water. When this tedious task is completed the female deposits the eggs, which may number from 1,000 to 4,000 according to the size of the fish. The eggs are adhesive and stick to the stones on the spawning bed. They hatch in about seven to ten days. The nest is protected during the incubation period but after hatching the baby fish are deserted.

 

[Henry2]

My fish used to do that all the time with the gravel in their tank, every morning they would move one side to the other building mountains with the stones. I would watch them suck up a stone then swim to the other side and spit them out, it was pretty funny.