The agency says muscle tissue and eggs from 30 paddlefish snagged this spring "have come back clear of any lingering effects" of oil exposure.
State fisheries chief Greg Power says a nonprofit group that processes paddlefish eggs into caviar sent the samples to a lab for analysis.
A broken pipeline spewed about 30,000 gallons of crude into the Yellowstone River on Jan. 17 west of Glendive, Montana.
Power says wildlife officials in Montana tested 213 fish on the Yellowstone River between the spill site and the North Dakota border. Power says none of those fish had any oil-related contamination.