Marine Hitchhikers: Natural Pest Control for Reef Tanks

You might think the shift from live rock to dry rock has reduced marine pests in reef tanks. Unfortunately, that’s not the case. Pests still find their way in – often hitchhiking on corals, invertebrates, or even second-hand equipment.

 

So, it remains critical to know how to deal with these plagues of pests. But before you go reaching for a bottle of chemical, why not consider a more natural approach: biological pest control. There are predators for all the pests out there, you just need to find the right one for your tank. Let’s take a look at some of the common options available in the trade.

 

Aiptasia Eaters

Aiptasia, or glass anemones, are among the most persistent pests of a reef tank. They are introduced on macro algae, corals, live rock, or just about any item that has come from another established marine aquarium. Once introduced, they will proliferate merely on light and food particles, stinging less aggressive coral polyps and multiply into the hundreds.

There are chemical controls like Red Sea’s Aiptasia X and mechanical, like ITC’s Reef Delete, but nothing is going to go at Aiptasia like a fish or shrimp, which can target them close up and potentially for all day, every day, until they’re gone.

Below are some of the stand-out options to consider for your tank, with options suitable for nano tanks through to large marine displays. 

Copperband Butterfly (Chelmon rostratus)

Pros:

• Excellent Aiptasia predator using its long, tweezer-like snout
• Can clear infestations and prevent regrowth

Cons:

• Requires larger tanks (300 litres/66 gal or larger)
• Sensitive and can struggle to feed once Aiptasia is gone
• May be bullied by aggressive tankmates

Top Tip:

Look for a specimen that is already feeding on frozen foods in the local fish store. Masstick, by Easy Reefs, is also another good option for your copperband. 

Aiptasia-Eating Filefish (Acreichthys tomentosus)

Pros:

• Ideal for smaller tanks (75 litres/16 gal or more)
• Easy to care for and often captive-bred
• Can eliminate and control Aiptasia long-term

Cons:

• Not all individuals eat Aiptasia reliably
• May nip at soft corals like zoanthids

Did you know:

Aiptasia eating filefish don't just camouflage using colour; their rough textured skin also helps them to hide amongst macroalgae.  

Stripey (Microcanthus spp.)

Pros:

• Hardy, active, and striking
• Eats Aiptasia and adapts well to aquarium life

Cons:

• May consume desirable corals
• Requires large aquariums (350 litres/77 gal or more)

More Info:

Stripeys are new kids on the block, recently becoming more available in marine stores. They can be kept in groups or singularly and may work in reef tanks without expensive LPS corals. 

Molly Miller Blenny (Scartella cristata)

Pros:

• Hardy, peaceful, and full of personality
• Suitable for saltwater tanks holding 100 litres (22 gal) or more

Cons:

• Can jump so you must use a cover. The D-D JumpGuard is a perfect solution. 
• May develop a taste for coral polyps

Did you know:

Molly miller blennies can reach a maximum size of 12cm (4.7") although they usually stay much smaller. 

Peppermint Shrimp (Lysmata sp.)

Pros:

• Reef-safe and suitable for nano tanks
• Can be kept singly or in groups

Cons:

• May ignore Aiptasia if other food is available
• Vulnerable to predation

Did you know: 

There are several similar looking shrimp known as peppermint shrimp including: Lysmata wurdemanni, L. boggessi, L. pederseni. For aquarists, it doesn't matter all that much as they all likely eat Aiptasia to some extent, but you must avoid the somewhat similar looking camelback shrimp (Rhynchocinetes durbanensis) as they are more likely to eat your corals. 

Berghia Nudibranch (Berghia stephanieae)

Pros:

• Specialist Aiptasia predator
• Ideal for tiny desktop reef tanks

Cons:

• Very delicate and easily predated
• Starves once Aiptasia is gone

Top Tip: 

Their tiny size makes them vulnerable to wavemakers and filter inlets. You may want to install covers and screens to prevent them from accessing these dangerous areas of the tank. 

Related article: How do I eradicate these coral pests?

Marine Flatworm Predators

There are two main flatworms we are interested in: the common rust brown flatworms, and the Acropora eating flatworms. Both breed rapidly in an aquarium without predators being present. The latter can devour any Acropora in the tank while the former may look unsightly and can smother your corals if their populations go unchecked. 

Luckily, there are some stunning marine fish that will happily help us out with a flatworm infestation. 

Sixline Wrasse (Pseudocheilinus hexataenia)

Pros:

• Hardy, active, and constantly hunting pests
• Great for smaller tanks

Cons:

• Can become aggressive, especially in tight spaces

More Info:

Unlike some species of wrasse, sixline wrasses do not require a deep sand bed to sleep in at night. 

Springer’s Damsel (Chrysiptera springeri)

Pros:

• Affordable and hardy
• Known for flatworm control

Cons:

• Territorial and aggressive toward tankmates
• Groups will often dwindle to just one or two fish over time as they pick on the weakest of the group.

Like This, Read This:

Find out about some of the other damselfish species available in the trade, and whether they are suitable for a community reef tank.

Spotted Mandarin (Synchiropus picturatus)

Pros:

• Peaceful and visually stunning
• Eats flatworms and microfauna

Cons:

• Prone to starvation without established live food sources

Top Tip:

Try to find a mandarin that is feeding on frozen foods in the store. Alternatively, make sure you have a good supply of live copepods, either in a culture, refugium or a reliable place to order from. 

Asterina Starfish Control

If you have ever had a reef tank you will have likely encountered an Asterina starfish at some point. At low populations they rarely cause too many issues, but when the populations get out of control corals may be at risk.

Harlequin Shrimp (Hymenocera picta)

Pros:

• Beautiful and highly specialised starfish predator
• Effective long-term control

Cons:

• Eats only starfish, and will eat larger ornamental species as well
• Must be rehomed or specially fed once pests are gone

Did you know:

The harlequin shrimp is not the only species of shrimp that loves to eat pest starfish. The bongo shrimp (Phyllognathia ceratophthalma) will also help with starfish plagues and looks equally amazing.

Bristleworm Control

These worms can multiply quickly in an overfed tank. They can actually be viewed as part of the clean-up crew, eating up left overs but they are unsightly, often creeping out reefers and non-reefers alike. Fortunately, you have a few options if you want to a species to help reduce their numbers. 

Some of the species recommended above for eating flatworms will also help tackle bristleworms too, perhaps most notably the sixline wrasse. However, for a more efficient, and unusual looking, species to control these pests look no further than the arrowcrab.

 

Arrowcrab (Stenorhynchus seticornis)

Pros:

• Excellent predator of bristleworms
• Interesting appearance and behaviour

Cons:

• May prey on small fish
• Can grow quite large

Did you know:

Females are the larger of the two sexes, and thus are more likely to predate on tankmates. You can tell the genders apart easily from the shape of the abdominal flap. 

 

Vermetid Snail Control

Vermetid snails produce mucus webs that irritate corals and inhibit their growth. They are often mistaken for worms by aquarists!

Bumblebee Snail (Engina mendicaria)

Pros:

• Small, affordable, and reef-safe
• Helps control vermetid snails

Cons:

• May prefer easier food sources
• Requires numbers for effective control

Did you know:

These small snails are at risk of being eaten themselves by mollusc loving fish like pufferfish and larger wrasses. 

Do you have a stunning reef tank? Share it with us for your chance to feature in the Practical Fishkeeping magazine! Email your photo to [email protected]. 

Final Thoughts

Natural pest control is one of the most rewarding aspects of reef keeping. It reduces reliance on chemicals while introducing fascinating behaviours into your aquarium.

However, success comes down to planning. Always research compatibility, ensure your tank can support the predator, and have a plan for what happens once the pests are gone.

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