Police found a 4ft spectacled caiman crocodile and 16 live snakes in an Essex house while searching it as part of a drugs investigation.
Officers said the creatures were found in a bedroom at the address in Burdett Avenue, Westcliff-on-Sea.
Among the 16 live snakes were pythons and a Madagascan giant hognose snake, and several that were classed as dangerous wild animals including cobras and copperheads.
A further seven snakes were found dead.
Detective Inspector Steve Nelson, of the Kent and Essex Serious Crime Directorate, said: "The reptiles were held in very poor conditions and sadly a number had died.
"We contacted the RSPCA, whose specialist handlers removed them from the house.
"Those that survived are now in the care of an RSPCA centre.
"We are working together with the charity as part of the investigation into how these wild animals came to be kept in such conditions.
"As officers we come across many different finds during our investigations and these are among the more unusual."
The house was searched as part of an ongoing investigation into a cannabis factory found in a Basildon industrial unit in 2015.
Officers who raided the cannabis factory in 2015 reported finding a number of reptiles including snakes, toads and spiders in the industrial unit.
Essex Police said they were found in "very poor conditions".
A 36-year-old man was arrested in Basildon on Wednesday in connection with the investigation, which then led police to search the house in Westcliff-on-Sea.
The man was arrested on suspicion of cannabis production, keeping a dangerous animal without a licence, and animal cruelty offences.
He has been bailed until February 13 pending further enquiries.