Starving snakes and lizards were left shivering in darkness when a Burgess Hill pet shop's bosses switched the lights off, a court heard.
One gecko was so thin it had to be put down after being rescued from Indigo Reptiles by RSPCA inspectors, magistrates were told.
A large monitor lizard had an exposed bone and part of its tail missing. A boa was so thin its bones were showing through its skin.
A hogsnake's scales were blistered and two other snakes were lying dead in their crate, showing the first signs of decay.
Five royal python hatchlings were also found with skin blisters.
RSPCA inspector Melissa Cox found the scene of "total neglect" when she visited the shop in Valebridge Road, Burgess Hill, on August 8 last year.
Owner Nathan Ring, 25, of Stonefield Way, Burgess Hill and his employee David Jupp, of Junction Road, Burgess Hill, deny 16 counts of causing unnecessary suffering to animals.
Ring also denies four counts of failing to comply with his licence.
Crawley Magistrates Court heard how Miss Cox visited the shop after receiving information about conditions inside.
She found many of the animals in darkness without the heat and ultra violet light they needed to stay healthy, said Rex Bryan, prosecuting.
He described it as a case of "total neglect."
Mr Bryan said Ring, who had run the shop for seven years, told the RSPCA: "My finances are very bad.
"I know I've not stayed on top of it but I have been trying as much as I could."
He told inspectors he had avoided putting on the heating to stop them over-heating.
Miss Cox told the court: "All the temperatures were wrong. The shop was in complete darkness."
The trial continues.
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