Around 45,000 animals over a five-mile radius have died after a train carrying toxic chemicals crashed.
Environmental officials believe 43,700 aquatic species were killed after the train derailed in Ohio on February 3.
It is more than 10 times the initial estimate, with health boss Mary Mertz claiming 38,222 small fish were killed, as well as 5,500 amphibians and other creatures and type of fish.
The train crash saw 38 cars derailed and a large amount of toxic chemicals released into the air, water and ground, The Telegraph reports.
Residents were evacuated from their homes due to concerns for their health after 11 of the cars were carrying hazardous materials.
It is thought a failed wheel bearing on one of the train's axle's is the reason the train derailed.
Investigators said the temperature of the failed wheel bearing increased by 215 degrees in a span of 30 miles but didn't reach the threshold heat for an alarm to go off.
Ms Mertz, who is in charge of the Ohio Department of Natural Resources, believes no land animals were killed as a result of the crash and that some fish have started to return to the waterways, mainly the Leslie Run stream.
"We haven’t seen any signs of fish in distress since that time," she said.
“Because the chemicals were contained, we haven’t seen any additional signs of aquatic life suffering. And in fact, we have seen live fish already return to Leslie Run.”
US Transportation Secretary Pete Buttigieg visited the crash site earlier this week, a day after former president Donald Trump visited on Wednesday to dish out Trump-branded water to residents.
Residents were left questioning the potential health effects they would face after officials seeking to avoid an uncontrolled blast intentionally released and burned toxic vinyl chloride from five rail cars, sending flames and black smoke into the sky.
Jennifer Homendy, head of the National Transportation Safety Board, said that the crash was “100 per cent preventable”.
She added: “We call things accidents. There is no accident. Every single event we investigate is preventable.”
The train was going about 47 mph - under the speed limit of 50 mph, according to investigators, who will complete a final report which will take between 12 and 18 months.
