The site, in Lodge Lane, was closed as a safety precaution after thousands of dead fish were found - due to a lack of oxygen.
The Environment Agency said this was due to water run-off from a fire at nearby Whitfire Shavings last week. There is nothing toxic in the water.
Aeration units have been used to raise the oxygen levels but have now been removed and the site handed back to Withnell Angling Club, which holds the licence for fishing.
Signs have been put up to warn people not to fish or let their pets go into the water.