Natural Pest Control

Mature aquaponics systems should be healthy enough not to encounter many pests or diseases, however it is useful to know ways in which you can protect your system without harming your aquaculture if there is an infestation.


The secret to protecting your plants naturally from pests, comes largely through Companion Planting. This works by growing sacrificial plants to attract or symbiotic plants to deter insects through scent or taste. It has been practised for a long time, especially amongst  biodynamic gardeners and within permaculture.


N snailOne of the most simple methods of control is manual, whereby you physically remove unwanted pests from the plants using your hand or a paintbrush. However, this can be time consuming because many are well camouflaged and are also minute, so can easily hide.

In the wild, abiotic elements such as wind, temperature and rain help control insect populations. Rain can prevent winged insects from flying and droplets knock them off of plants. These abiotic factors can be replicated within aquaponics. Rain can be mimiced with a spray bottle filled with aquarium water (not tap water) A fan can be used to replicate wind and temperature can be controlled by use of heaters.

 APHIDS Aphidoidea aphididae

Aphids, also referred to as whitefly, greenfly etc are tiny green, brown, black or almost colourless insects which are quite incredible. Most species are monophagous (feed from only one plant species) They feed off of sap from the phloem vessels of plants (because the phloem is under positive pressure, so is forced into the aphid’s food canal), although occasionally some ingest xylem sap (which requires sucking). When food sources become low, they can produce offspring which have wings in order to source new food!


Ants farm aphids, in a similar way to us farming cows. The Ants will defend aphids from attack, and in some cases store aphid eggs in their nests over winter and carry them to a plant once hatched. In return, they “milk” the aphids for honeydew by stroking the aphids bodies with their antennae. This honeydew can lead to mould forming on plants.


Aphid infestations destroy plants. Infected plants should be removed away from healthy plants, watch out for aphids falling on other plants at this point. Aphids should then be removed manually. If infestation persists there are other forms of control:

PARASITIC WASPS Encarsia formosa

Not for the feint hearted, this method involves introducing tiny specialist wasps which lay their eggs inside the aphids to hatch. This was a widely used method of control in greenhouses in the 1920’s, but unfortunately, was replaced with chemical pesticides, although more people are beginning to steer away from harmful chemicals now.

LADYBIRS AND THEIR LARVAE Cucujoidea coccinellidae

Also called Ladybug/ Ladybeetle/ Ladycow. They prey on aphids, mites and soft-scale insects. Ladybirds consume thousands of aphids a year (which is usually their lifetime), with each of their larvae consuming around 400 aphids before reaching the pupal stage.


 SPIDER MITES Tetranychus urticae

Are tiny, but are known to feed on hundreds of different plant species. Optimum conditions for them to breed are when it is hot and dry. Females can lay up to 20 eggs a day. Infestation is characterised by silk webbing, similar to spider’s webs.


VENTILATE Ensure your space is well ventilated to encourage air flow.

 PREDATORY MITE Phytoseiulus persimilis 

A larger predatory mite, which reproduce at double the rate to spider mites above temperatures of 18°C they consume up to five spider mite adults or twenty of their eggs a day.

LADYBIRDS AND THEIR LARVAE Cucujoidea coccinellidae (see above)




Plant derivative sprays either kill the pest and are called Pesticides or repel pests so they don’t settle – these are called anti-feedants.

Absolutely no chemical pesticides or fertilisers can be used in aquaponics because they are harmful and could destroy your eco system. Instead problems can be resolved by using organic remedies.

Important note: Always remove affected plants from aquaponics before treating. This prevents infestation spreading to other plants and ensures fully that the products don’t get into the water and harm your aquaculture. (e.g soap stunning fish, or chilli stinging their eyes)



Non-toxic oils control mildew and fungal problems, especially for citrus, fruit and vegetables.


This sometimes needs to be added to aquaponics systems anyway and is especially useful for pest control in outdoor systems. Slugs and snail pellets often contain chelated iron as it slows down their metabolism until death occurs.


Manufactured from biodegradable fatty acids such as natural soap, vegetable or coconut oil. This pesticide is easy to make at home, and kills aphids, greenfly/whitefly, mites and thrips. (Recipe below) Soap stuns fish, so take care not to get it in the water.


Prevents insects from moulting, reduces mobility, inhibits feeding and disrupts eggs, pupae and larvae. Should not get in the water, so should only be used sparingly.


Interplanting Garlic, Chilli, Chive, Mustard and Onions  in your aquaponics will most likely help repel fungus and pests. If aphid infestation occurs, you can also use the fruits to make a spray, but use sparingly and be careful not to get this in the aquarium water.


  • 1 garlic bulb (most members of the Allium family repel insects)
  • 2 hot chilli peppers (If unavailable try 1-2 spoon hot chilli powder or crushed chillies)
  • 1 tablespoon vegetable oil (this suffocates the insects, but can also clog leaf pores)
  • A couple of squirts of vegetarian washing up liquid (optional as soap can stun fish)
  • Dilute with water


  1. Chop the garlic and chilli finely or mix using a blender.
  2. Transfer into a saucepan and add the other ingredients, heat gently whilst slowly adding the water.
  3. Leave to cool and strain the contents through muslin or coffee filter into a clearly labeled spray bottle.
  4. Remove plants from aquaponics and apply spray to infested areas, making sure to search deep into plant nooks and underside of leaves.

Be careful: Only apply as a foilar spray. Avoid getting the mixture in the water because the chilli could harm the fishes eyes, and the soap could stun your fish.

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