Step 1: Understanding the Concept:
Aflatoxins are highly toxic, mutagenic, and carcinogenic mycotoxins produced by specific molds under favorable warm and humid storage conditions.
Step 2: Detailed Explanation:
Aflatoxins are produced primarily by molds of the genus Aspergillus, particularly Aspergillus flavus and Aspergillus parasiticus.
If smoked fish is not sufficiently dried or is stored under humid conditions, these molds can grow on the surface and synthesize aflatoxins.
Pseudomonas, Clostridium, and Acetobacter are bacteria and do not synthesize mycotoxins.
Step 3: Final Answer:
Thus, aflatoxin formation in smoked fish is caused by the action of Aspergillus.