It might have been fine through the summer, but state officials said it got too cold for a South American fish dumped in the Otter Creek.

Two Vermont Marble Power Division employees spotted the 15-inch, 2.5-pound pacu, a cousin to the piranha native to the Amazon and Orinoco basins, near the dam in Proctor last week.

"It was pretty much dead," said Shawn Good, a fisheries biologist for the Vermont Department of Fish and Wildlife who claimed the fish. "I think it was in the last throes of death, which is not unusual because this is a South American species and it's not adapted to cold temperatures."

Good said the fish did not survive until he arrived and that its remains have been deposited in a Fish and Wildlife freezer.

"It's just going to stay in the freezer," he said. "It's going to be archived for the future as a sample specimen."

The fish could not have been in the Otter Creek before the summer, Good said, and could not have survived there much longer.

"Once the water temperature gets down into the low 60s, they can't stand it," he said. "The negative impact to the Otter Creek was pretty much zero. The worrying thing is the propensity of the public to release their fish in the wild."

Pacu are sold as exotic aquarium fish, and Good said many fish like it have been pulled out of Vermont waters after aquarium owners abandon them there.

"I think it's fairly common, unfortunately, across the country," he said. "People who own aquariums sometimes don't know what they're getting into."

Good said a fish might get too large or start eating too much.

"They want it to live," he said. "They want it to be happy, so they let it off in the local pond or wherever."

If the fish survives, it can go on to have problems with, or cause problems for, native species. Some species released into the wild from aquariums can become invasive.

Even species unlikely to live long enough to become invasive can cause problems. While pacu are herbivorous, Good said he has seen them sold alongside piranha. One of the latter released into the wild could have bit and injured someone in the course of the summer, Good said.

Vermont has outlawed releasing such fish into the wild, Good said.

He said owners looking to dispose of one should turn it over to another aquarium owner or euthanize it by placing it in a container of water in a freezer. Because cold temperature is a natural anesthetic to tropical fish, it is considered an acceptable method of euthanasia, according to the Fish & Wildlife Department.

gordon.dritschilo@rutlandherald.com