During the course of the wildlife series, The Wild Ones, viewers are taken behind-the-scenes here at the Two Oceans Aquarium. Not only will they be introduced to the people who work "behind the doors", but they will also meet some really weird, wonderful, and often overlooked animals.

Catch The Wild Ones, every Sunday at 4pm on M-Net (channel 101).

Welcome to Quarantine – the area in the Aquarium where all the animals you see in our wonderful exhibits start their stay with us. Nicholas Nicolle, our Senior Aquarist - Animal Health & Husbandry is in charge of ensuring that all the animals that enter the Aquarium undergo the necessary treatment and quarantine period before they are relocated to their new exhibit homes. It turns out that Nic has a strange fascination with animals that we would normally avoid – parasites. I had a chat with him about these critters and his love (yes, we said love) of them.

“Something that lives on another animal and completely and wholly relies on the host animal for survival. The host animal does not benefit from this relationship but it provides the resources for the parasite to live. ” – Nic's definition of a "parasite"

Nic seeing to the health and well-being of our sharks. Photo: Devon Bowen

Nic started at the Aquarium looking after the frogs and jellyfish. When the Quarantine position opened up, Nic took over. And he hasn’t looked back. Nic studied Ichthyology and Quarantine was the best place for him to work directly with all the animals that were coming into the Aquarium.

“A good parasite shouldn’t kill its host, because if it kills the host, then the parasite can potentially die too. Some parasites however, do – it just depends on the lifecycle.” – Nic

“I didn’t necessarily have an interest in parasites to start off with, but through my work and interest in the fish, I became more and more interested in parasites. Also, through working with David Vaughan, the Aquarium's previous parasitologist, I grew to love parasites and their function and how they interact with different fish species. I am currently doing my Master's on Ichthyophonus, which are found in the blood-rich organs of fish”, said Nic.

Ichthyophonus on a sand steenbras liver. Photo: Nic Nicolle

While many parasites are really, really small, some, like the parasitic mouth isopods, are big and prominent… once spotted.

“You sedate the fish and then open its mouth, and there, staring back at you, is a pair of eyes! Sometimes there is even more than one pair! We remove these guys manually,"  Nic chuckles.

Say aaahhh! And there it is, a parasitic isopod. Photo Nic Nicolle

For external flatworms (Monogeneans), Nic uses a freshwater bath to remove them from the fish. For internal parasites, he uses the same deworming medication that you would give to your cat or dog.

Flatworm found on a spotted gully shark. Photo: Nic Nicolle

It is very easy to think that out in the ocean, all animals are absolutely pristine, but the reality is that very many, if not all, carry some type of parasite. In the wild, an animal with a healthy immune system is able to keep these parasitic populations in check. In the Aquarium, the story is a bit different.

“When moving fish around, it causes stress. This compromises the fish’s immune system, which makes it more susceptible to an increase in parasite numbers. We have to treat these animals to ensure that their optimal health is maintained. Also, in the confines of the Aquarium, the same animals can be re-infected if all the parasites, and all of their life stages, are not removed.”

That's just a little bit gross. Manually removing external parasites from sharks. Photo Devon Bowen

So, Nic, are there any marine parasites that can be detrimental to human health?

“Yes, there is one called Mycobacterium marinum, more commonly known as 'marine TB' and some aquarists end up with this, especially on their fingers. Then there are also the worms you sometimes find in snoek. Those can cause allergic reactions.”

Nic mentioned that he worked with David Vaughan. David is a bit of a legend here at the Aquarium as he was our first “parasite guy”.  David has authored and co-authored many papers and has even described four previously unknown parasites that were found right here at the Aquarium.

I took this opportunity to have a long-overdue catch-up with David.

David Vaughan in his lab in Australia. Photo: David Vaughan

Since leaving the Aquarium in 2012, David has gone on to grow tremendously in his field of study. In 2015, he moved to Australia where he has had the opportunity to work with Dr Kate Hutson, one of the top fish parasitologists in the world. He was awarded two competitive scholarships to do his PhD with her at James Cook University in Townsville, Queensland.  His PhD work re-evaluated the concept of cleaning symbiosis, redefined it and then evaluated the efficacy of cleaner shrimp species as biological controls against economically important parasites of cultured finfish in aquaculture. This is similar to the use of cleaner fish in salmon farming in Europe, but is the first-ever work done using shrimp as a biological control against parasites in cultured fishes, and is superior to the cleaner fish model because shrimp not only remove the parasites from the fish, but also eat the environmental stages of the parasites that are responsible for reinfections.

“Cleaner fish can't do the latter and they are also susceptible to some of the parasites they are employed to control. Shrimp are not. Essentially, I have taken parasitology a step further and have looked at other symbiotic interactions, and how nature controls these problems," says David.

They might be small, but in large numbers they can become a big problem. Photo: Devon Bowen

“It is a fascinating world we live in! My focus is now very much on how this type of work can be implemented in aquaculture to reduce parasitic disease, and also how it can reduce the reliance on chemicals as traditional treatments. Aquaculture globally will need to double by 2050 to produce enough protein to feed a global population, but diseases remain the largest constraint. Resistance to chemical therapies by parasites and other superbugs is already a reality, and will limit our use of traditional chemical controls in the future, so biological controls in aquaculture are certainly going to increasingly become a necessity, and the time for their discovery and development is now,” David enthused while poring over slides of worms, parasites and other unknown biological matter.

Tune into the M-Net 101 on Sundays at 16:00 for the next episode of The Wild Ones: Aquarium: An Aquatic Life to delve even deeper into all things underwater.

Want to know more? #AskAnAquarist!

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