Can you compost fish? Yes – with caution!

  • Date: June 1, 2022

There is no denying it – as a nation, we are terrible for wasting food. And most of the time it ends up in landfill. Composting diverts the amount of food waste heading to landfill – but, despite what most people think, not all food can be popped in the home compost pile. Fish (and fish guts) are compostable, but the EPA advise against it since their odor make them a target for pests. Experienced composters often add them to their composting pile – ensuring they are buried deep and subjected to high temperatures. Here we will take a closer look and offer an alternative to dispose all of your food scraps easily – including fish.

Firstly, is fish biodegradable?

The first step in deciding if an item is fit for the compost pile is determining if it is biodegradable or not. Anything that can be broken down naturally by microbes, such as bacteria, is termed ‘biodegradable’. In general, anything that came from nature is biodegradable – essentially, the component parts return to nature. All parts of the fish will biodegrade in suitable conditions, including the guts and bones. However, different parts will biodegrade at different rates.

So, can you compost fish?

Home composting reduces how much waste we send to landfill – and it provides a homemade (free!), nutrient-rich fertilizer for your garden. As households seek to live in a planet friendly way it is becoming more and more popular. And it is easy to understand why – it will save you money and it is good for the planet! Everybody wins.

We have seen that fish is biodegradable, so you might think it automatically qualifies for the compost bin. Unfortunately, it’s not as simple as that. Despite what many people may think, the terms ‘biodegradable’ and ‘compostable’ are not interchangeable. They do not mean the same thing, there are subtle differences between the two terms. To be compostable an item needs to be biodegradable but not all biodegradable items are compostable! There can be several reasons a biodegradable item can’t be composted at home – from containing harsh chemicals or biohazards to being too smelly and attracting unwanted local wildlife…

The United States Environmental Protection Agency (EPA) advise against composting fish and fish scraps. They think its odor is likely to attract pests. It is difficult to argue with their reasoning – who really wants a smelly, rodent-attracting pile in the backyard?

Some considerations if you decide to compost fish…

Even though it is advised against, people still compost fish. As always it is, ultimately, up to you what you add to your compost pile. However, composting can be a complicated business – its not as easy as just throwing in some food and garden scraps and waiting for a while. We recommend if you are new to home composting to give fish composting a miss, for now. Stick to more straightforward items such as peanut shells and cardboard.

If you do add fish scraps, make sure that they are deep within the pile – pests won’t be able to sniff it out quite as easily. Cover it with a few layers and you should be good to go! Another popular recommendation amongst experienced composters is to only add fish to your pile if it is reaching temperatures of 130 degrees Fahrenheit.

If don’t want the hassle of standard composting, compost it Bokashi style!

If you don’t want the headache of composting fish (or their guts) in your home pile, there are food waste collections in some areas. Typically, all cooked or uncooked foods can be collected – this is a great option for foods that a bit more awkward to compost at home, like fish and dairy produce. Have a look in your local area to see what is available.

However, if you want to do-it-yourself at home (and get some homemade fertilizer in the process) there is another alternative to standard home composting. Bokashi composting, in a nutshell, involves the fermentation of leftover food scraps. The process takes place in an anaerobic sealed container. This is ideal for disposing of fish scraps as pests can’t get to it! It is quite quick too – food scraps, generally, only take between 4-6 weeks to breakdown into a ‘pre-compost’. This can be buried in the garden or added to the standard composting pile.

The bottom line

Home composting of fish is not recommended by the EPA. Its foul odor is likely to attract wildlife. For many, it is simply not worth the headache. If you don’t have a local food waste collection who compost food on a massive scale, don’t worry!  

Even better, try Bokashi composting – a quick and easy alternative. It will provide you with a nutrient rich compost in next to no time. The set-up is a bit more costly than typical home composting, but a Bokashi composter is a wonderful addition to any kitchen – especially when you have fish scraps, and other controversial home composting items like cheese, left over.