Police officers have shut down a cannabis factory in Plumstead where nine catfish were also discovered.
Officers discovered the fish and a large number of cannabis plants at the site on Plumstead High Street on Saturday morning.
The animals have now been placed with the RSPCA, police said.
No arrests have been made.
Plumstead Police posted a photo on social media showing two catfish swimming in murky water at the property.
Another shows a large number of cannabis plants surrounded by fans and white sheets.
Officers were called at around 11.30am after members of the London Fire Brigade dealt with a fire at the property.
Enquiries are ongoing.
Plumstead officers tweeted: “Plumstead SNT officers closed down a Cannabis factory on Plumstead High Street SE18.
“There was also concerns regarding animal welfare.
“RSPCA attended taking 9 Cat Fish to a safe place due to the conditions they were kept in. #Teamplumstead #ThankYouAbbeyWoodSNTForYourAssistance.”