What to Do With Fish Cleaning Waste

Fish cleaning creates a unique waste stream that needs special attention when the facility is served by a septic system

What to Do With Fish Cleaning Waste

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In winter, spring, summer or fall people are catching and cleaning fish across the U.S. Sometimes at parks and resorts, fish cleaning buildings are installed at a convenient location for this activity and often include sinks with running water and counters to work.

The question then is what to do with the solid waste and wastewater when the facility is served with a septic system? If you are designing or maintaining a system on a property where fish cleaning will take place, you should consult your local unit of government regulations to determine what is allowed, but below are some considerations. It is also important to keep in mind that other applicable local standards may exist that govern this waste stream, so it is important to contact the local regulatory authority when working with a fish cleaning shack.


The leftover parts of dead fish: heads, tails, scales, internal organs, etc., are a challenge to deal with. In the past it was common practice to dump fish waste back into the lake, river or ocean. The trouble is that dumping those remains depletes oxygen in the water and increases the nutrient load, overloading the ecosystem; so dumping is banned to protect our water bodies and animal and human health. 

To make collection of the solids as simple as possible, buckets should be provided. The best approach for treating this waste is typically composting. In composting, the high-nitrogen fish waste and seafood shells are mixed with coarse, high-carbon dry materials such as shavings, wood chips, leaves, branches or bark. Microorganisms in the pile feed on the waste and over a period of several months convert it into rich humus. In the process, the microorganisms generate a great deal of heat that reduces pathogens in the product, eliminating odor, disease organisms and destroying weed seeds. Great free composting resources can be found online.

Education of the users is critical. Make sure there is good signage instructing them what to do with the solid waste.


If a fish cleaning building has a sink with pressurized water plumbed to it (i.e. running water), the waste produced from that sink needs to be treated. It is not recommended that the sink be connected to the septic system due to the likelihood of fish waste going down the drain. The sinks in these facilities should be fitted with screens which cannot be removed by the public to project the plumbing and septic system. Even with a drain screen small scales and other debris from fish cleaning activities may reach the tank. Some of these cleaning stations have commercial sized garbage disposals that grind up very large fish debris. These garbage disposals would create a huge load if connected to a septic system. A better option than connecting this waste stream to the septic system is a holding tank fitted with a high-water alarm that is pumped when full. 

Floor drains

Fish cleaning buildings with floor drains used for incidental spills, floor washing and general cleanup generally do not need to be connected to the septic system and can be plumbed to daylight. These floor drains should also be fitted with a screen to prevent debris from the floor from enter the piping. Fish cleaning wastewater should not be going down the floor drain. It’s important to note that while daylighting the floor drain waste may be an option, the waste stream should not discharge directly into a lake, river, stream, ditch or ocean but soak in near the facility. If the decision is made to plumb the floor drain to the holding tank, the size should be increased to account for this additional flow.  

About the author: Sara Heger, Ph.D., is a researcher and educator in the Onsite Sewage Treatment Program in the Water Resources Center at the University of Minnesota, where she also earned her degrees in agricultural and biosystems engineering and water resource science. She presents at many local and national training events regarding the design, installation and management of septic systems and related research. Heger is the President-Elect of the National Onsite Wastewater Recycling Association and she serves on the NSF International Committee on Wastewater Treatment Systems. Ask Heger questions about septic system design, installation, maintenance and operation by sending an email to kim.peterson@colepublishing.com.


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