The Environment Agency have been called to Bexhill after a large number of fish were found to have died in park pond this week.
Fish in the pond of Egerton Park in Park Road, were reported to have died sometime on Sunday, August 13.
Earlier this week, Rother District Council confirmed it is working to resolve the issue but could not give an exact figure on the number of fish affected.
A spokesman for Rother District Council said: “It is impossible to say how many fish have been affected, but our park officers are working hard to remove those that have died.
“These are predominantly young sea bass, but we are aware that eels and other fish have also been affected.
“We are continuing to work with the Environment Agency to establish the cause.
“Initial evidence suggests that the deaths could have been caused by naturally occurring algae.”
Since then an investigation by the Environment Agency confirmed an algae present in the water was responsible, as it removed oxygen from the water.
An Environment Agency spokesman said: “This lake is not stream fed and fills with saltwater via an in inlet from the sea. Due to low tides, the inlet has not carried any water through to the lake which has caused it to be quite stagnant.
“The Environment Agency took a sample of the water and received confirmation from our laboratory that algae was present.
“Due to the type of algae found the Environment Agency classed it as a ‘bloom’ and are confident this was the cause of the fish deaths.
“Over the weekend it seems the oxygen levels crashed to a level where the pond couldn’t sustain life due to this ‘bloom’.The ‘bloom’ is broken down by large amounts of bacteria, as the bacteria feeds it strips oxygen from the water.
“The Environment Agency have been providing advice and guidance to Rother District Council who own the lake and have been clearing it of the dead fish.
“We want to thank the members of the public who initially reported this incident to us so we could respond and take the necessary action with Rother District Council.
“If you do see a pollution incident, dead fish or fish in distress please report it to our dedicated 24 hour incident hotline on 0800 80 70 60.”
Earlier this month dog walkers were warned to avoid Alexandra Park in Hastings after blue green algae was found in some waters there.
While the two cases are not thought to be connected, any suspected blue green algae should be reported.