A businessman ordered 13 endangered and poisonous frogs before making arrangements with another man to deliver the live animals to him from Malaysia.
Singaporean Jonathan Wong Kai Kit passed $100 to Mitchell Edberg Li Heyi, 31, as part of the transportation fees for the poison dart frogs, whose natural habitats are in Central and South America.
Another $140 was to be handed over after Wong received the frogs in Singapore. He intended to keep them as pets.
But Li was caught after driving into Singapore from Johor Baru at the Woodlands Checkpoint on Nov 10 last year.
A total of 18 poison dart frogs were found in the car with four other live animals, including a sugar glider and an Argentine tegu, a type of lizard.
Wong, 32, was fined $6,600 on Wednesday after pleading guilty to an offence under the Endangered Species (Import and Export) Act.
He had abetted Li in importing into Singapore six amphibians known as Anthony's poison arrow frog, a species of poison dart frog, without a permit.
Two other similar charges involving seven poison dart frogs were considered during sentencing.
The Straits Times understands that this is the first case here where an offender was dealt with in court over the unlawful importation of such frogs.
The case involving Li, who is also a Singaporean, is still pending.
Court documents did not state what he intended to do with the animals not linked to Wong's case.
A 2015 BBC report stated that Anthony's poison arrow frogs harbour two powerful alkaloids called epibatidine and phantasmidine.
It said: "According to a study published in 1998, even tiny amounts of epibatidine can cause severe damage to an animal's brain and muscles. This can lead to respiratory paralysis, high blood pressure, seizures and death."
National Parks Board prosecutor Wendy Tan said Wong owns a company called Zookeeper, which deals with vivariums - enclosures or structures prepared for keeping animals.
He had earlier pre-ordered five poison dart frogs from Li. Wong also bought another eight from a man known only as Tom, who owns a pet shop in Kuala Lumpur.
Ms Tan said Wong paid Tom RM3,050 (S$1,000) for the eight frogs.
The 13 frogs were among the 18 Li was transporting into Singapore last November.
On Wednesday, defence lawyer Tania Chin told the court that her client did not know the frogs were endangered. She added that there was also no evidence that he wanted to breed or sell them.