Health authorities were called in to investigate the source of the suspected contaminated tuna after four people showed symptoms of Scombroid poisoning — poisoning due to consumption of rotten fish, Sky News Australia reported.
The customers had ordered tuna salad in Soul Origin cafe near Town Hall station.
The South Eastern Sydney Local Health District said the fish may not have been stored correctly.
The cafe, which insists it meets the highest hygiene standards has changed its brand of tuna since the customers fell ill.
The cafe’s customers suffered symptoms including skin rash, dizziness, tingling in the mouth and nausea after consuming the salad.
Scombroid was linked to the death last year of Queensland mother and daughter Noelene and Yvana Bischoff, just hours after they ate contaminated fish at a restaurant in Bali.
The Sydney cafe episode follows a Hepatitis A scare involving frozen berries imported from China.
Eighteen people have so far been diagnosed with Hepatitis A linked to the berries, a week after a nationwide recall was issued for a range of products.