The mysterious fish were at risk of decimating the frog population in the Vinegar Pond at Mousehold Heath when they first appeared.

It prompted the heath's maintenance team to take a “nuclear option” of draining the pond to clear it of the killer carp in 2024.

But now, sightings of the fish have been confirmed by park officials.

Green councillor at Sewell Ward said: "The fish are back. The warden has seen four small fish in the pond.

Sewell councillor Gary Champion (Image: Newsquest)

"We are going to keep monitoring the population and if we need to take action.

"The wardens have done a spectacular job but some of the fish slipped the net.

"The are the remnant population of the removed fish from when the pond was drained.

It is believed some of the fish may have slipped the net (Image: Gary Champion)

"It is a frustrating, we may have to intervene but the numbers are very low."

Mr Champion said the fish may have been able to survive the drained pond in the wet mud which was left behind.

The pond was emptied to remove more than 6,000 goldfish and koi carp that had been mysteriously put into the water.

The draining was carried out by the heath maintenance team to stop the fish from decimating the local frog and newt population.

The pond was drained in 2024 (Image: Gary Champion)

Mr Champion added: "The frog population is doing well. There are 120 clumps of spawn there, possibly more."

This decision followed two previous attempts at removing the fish using electrofishing, which stuns the fish and allows them to be caught.

It is believed the goldfish and koi were introduced to the pond at some point in recent years, likely during the Covid lockdowns, before breeding out of control. 

This is unusual as any offspring between the two are supposed to be sterile.

When born, some would be born brown or grey and turn orange as they get older.

Sightings of the fish have been confirmed (Image: Gary Champion)

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