The problem was first reporter on November 19, and earlier this week more fish have washed ashore on both sides of the Garden Island Causeway, near Point Peron boat ramp.
Fresh checks will be undertaken by the Department to establish how the fish died.
Department of Fisheries research scientist Michael Snow said several departments were doing everything they could to identify the cause of the fish deaths and had all but ruled out disease and lightning strikes.

“I appreciate the frustration that’s out there at having not identified a single cause as of yet, these things can be extremely difficult,” Dr Snow told ABC local radio.