Marron are about the best tasting freshwater crayfish there is, and their benefits don’t stop at your tastebuds.
Marron (Cherax cainii) are superb eating and there is an argument that they taste even better out of an aquaponics system.
Marron bought at fish markets or on the menu at a restaurant have been farmed in dams, which are a muddy environment. Whilst marron are purged (left in clean water tanks for a few days without food to work the muddiness out of their system) they commonly still have an ‘earthy’ taste to them.
In an aquaponics system there is no mud, sand, or silt so you will taste the pure flavour without a hint of earth.
Within the aquaponics system marron have proven benefits.
Stirring up the bottom
Marron contribute to the aquaponic ecosystem by stirring up the bottom of the tank and eating uneaten fish feeds and other organic material that sinks to the bottom of the tank.
Even with your pump, water draining back to the system, and air tubes, your aquaponics tank is likely to have ‘dead spots’ or areas where the flow of water is poor. These areas can see a build-up of organic matters potentially contributing to poor water quality. The movement of marron through these areas stirs up this material and increases the chances of it being picked up and pumped into your growbed (or solids filter).
Eating Uneaten Fish Feeds
Overfeeding fish is one of the leading causes of poor water quality in an aquaponics system and it’s not always because you fed them too much. Sometimes the fish aren’t hungry and other times they will take the feed, only to spit it out under water. In both cases you aren’t going to be able to scoop out uneaten feed. Marron is your insurance policy to make sure that feed sitting on the bottom of the fish tank isn’t going to build into a problem.
The problem with Marron
Marron taste so good that even other marron think they taste good too. Marron eating each other is very common in an enclosed environment and here are a couple of tips to help you avoid disappointment:
Don’t have more than one marron per square metre of fish tank. Any more than that and you will run into problems.
Marron grow by shedding their hard shell (moulting) and slowly hardening the soft shell that had developed underneath. 90mm PVC piping must be added to the tank to give marron the ability to hide, especially when they are soft shelled after a moult. A couple of marron will coexist in the same fish tank however there is an increased risk of attack during a moult.
One method to increase stocking density while decreasing chances of cannibalism is to break off the top closing pincer on each claw. Although the claw will slowly grow back (meaning you will need to do it again) it needs to be mentioned that marron are very shy and sensitive creatures. Although the act of breaking off the pincer doesn’t harm the marron, the stress caused will lead to losses. I’ve always thought that if you broke the pincers of 10 marron the about 3 wouldn’t make it.
Tips for buying
Marron can be bought very easily in Western Australia. They are expensive in aquarium shops and less expensive at places that sell large numbers of koi, although the marron are likely to be quiet small here. Marron can be bought live at fish markets and you can order direct from marron farms, however most marron farms will have a minimum order of about 5kg.
For people outside of Western Australia, the same concept works for Yabbies. Although smaller than marron, yabbies are far more aggressive and increase the probability of cannibalism.
Barbecued Marron with Garlic & Herb Butter
Just reading this menu title makes me drool! However marron are an important contributor in aquaponic ecosystems and should be considered for this reason alone.