The use of vaccines and treatment of diseases at finfish farms are important fish health and welfare matters that are overseen by Biosecurity Tasmania. Public health issues associated with the use of antibiotics are the responsibility of the Department of Health. Approvals for use of antibiotic chemicals in animal husbandry are handled by the Australian Pesticides and Veterinary Medicines Authority.
Treatment of marine farmed fish only occurs based on veterinary advice. Antibiotic use declined significantly after 2006-2009 due to the development of vaccines, as shown below. In 2025 antibiotic use increased to control disease caused by P. salmonis (Piscirickettsiosis), for which further vaccine development is underway.
Figure 1: Use of antibiotics (active medication in kg/year) between 2003 and 2024
Accessible version of this graph
EPA Role
The EPA's responsibility is to ensure that the use of antibiotics in finfish farming does not cause environmental harm. This is done through monitoring of antibiotic residues in the environment.
Following notification of medication events, the EPA requires licence holders to conduct comprehensive monitoring of antibiotic residues in seabed sediments, wild fish and the water column.
For wild fish sampling, the end of the monitoring program coincides with the number of 'degree days' corresponding to the withholding period for farmed salmon specified under food safety regulations.
Antibiotic residue monitoring is required to continue until levels determined through analysis at an approved laboratory are below the specified thresholds.
It is the EPA's current practice to make antibiotic residue monitoring reports public after residue monitoring is completed, usually within a timeframe of 3-6 months from the commencement of monitoring. Interim reports may be issued in the case of more prolonged monitoring events.
The
monitoring schedule developed by the EPA is designed to track potential
antibiotic residues over time and assists in the understanding of antibiotic
fate in the receiving environment. Monitoring intensity (e.g. number of
monitoring sites) in the past has been determined using a risk-based matrix
taking into account the amount of medicated feed used during treatment and
site-specific factors.
The EPA's approach is consistent with findings of a risk assessment undertaken by Food Standards Australia and New Zealand (FSANZ), which was undertaken to identify the risk associated with consumption of recreationally caught wild fish and escaped farmed fish following treatment with oxytetracycline (a commonly used antibiotic). The FSANZ risk assessment did not consider the commercial harvest of salmon, as salmon destined for sale must comply with the Australian New Zealand Food Standard Code which specifies a maximum residue limit for oxytetracycline of 0.2 mg/kg.
Antibiotics currently used in Tasmanian finfish farming are oxytetracycline (OTC) and florfenicol.
Oxytetracycline
Monitoring reports for oxytetracycline usage can be found on the D'Entrecasteaux Channel, Huon River and Port Esperance and Okehampton Bay in Mercury Passage on the East Coast marine finfish farms pages and the Use of Therapeutants in the Freshwater Environment page.
Florfenicol
During 2025 and in response to the industry's proposal to use florfenicol to treat disease caused by P. salmonis, the EPA developed a new Antibiotic Residue Monitoring Schedule through a review of scientific literature and with support from Public Health Services.
Information in relation to florfenicol treatments, monitoring requirements and reports, when published, can be found from the Florfenicol page.