Fungi naturally produce secondary metabolites which have been investigated as biologically active compounds. This work aimed at exploring phenolic compounds profile of three fresh-water derived fungi, and investigating the antimicrobial and larvicidal activity of methyl gallate and p-coumaric acid as two major compounds detected. Reverse phase high performance liquid chromatography coupled with diode array detector (RP-HPLC-DAD) revealed the presence of 22 phenolic compounds in the filtrate extracts of Penicillium implicatum, Aspergillus niveus and Aspergillus petrakii, although they varied in their concentrations from one species to another, methyl gallate was one of the major compounds in Penicillium implicatum and Aspergillus niveus filtrates, and the compound of the highest concentration in Aspergillus petrakii filtrate. While p-coumaric acid was the major compound in Aspergillus niveus filtrate. Methyl gallate was effective on Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus sub sp. aureus (MRSA), while p-coumaric acid was only effective on Bacillus cereus. Regarding larvicidal activity, p-coumaric acid was more effective on Schistosoma mansoni cercariae than methyl gallate. The investigated fungi comprise a rich source of phenolic compounds, and methyl gallate and p-coumaric acid represent promising antibacterial and larvicidal agents.