Tilapia Termination

By Nickfish

Tilapia are decimating many waterways. How did they get here, what do they do to our waterways and how can we stop from spreading further?

There are a number of tilapia species and the one that is most commonly encountered in Australia is the Mozambique tilapia. These fish are deep bodied, with a slimmer profile and the males will have large lips and mouths like a red throat. They are often olive or silvery grey and sometimes have blue scales along the back when spotted in the water (colours vary depending on the water clarity and quality).

A tilapia's fins are quite different to many native fish, like Australian bass and barramundi, which will have an indented section on their dorsal fin and a rounded end. Tilapia on the other hand have a continuous fin and an extended, pointed end. This is the same as the pelvic (stomach) fins on the tilapia, which are quite long and nearly touch the anal fins. In contrast these fins on native fish are quite short (on most fish).

How did these fish get to Australia and how did they spread so quickly?

Tilapia are native to Africa and were brought into Australia in the 1970s as an aquarium fish, before making their way throughout Queensland, where they are now considered one of the greatest threats to our native waterways. Tilapia are very resilient fish, making it easy for them to invade the waterways. They can survive out of water for long periods of time, but what makes them so invasive is their breeding habits. They make a nest and by doing this they rip apart the vegetation on the bottom, lowering oxygen levels and creating less structure for many smaller fish and crustaceans. This means less structure to hide in and larger fish, including the tilapia then destroy the population.

The females can carry their fertilized eggs and fry in their mouths. The problem with this is that if something were to happen to the mother, like being caught or being eaten by a predator, she will drop the eggs and they will still hatch. They can also survive for extended periods in the mouth of the mother when removed from the water, so live or dead tilapia should not be returned to the water.

Another capability this fish has is the ability to mature early and grow to small sizes; known as stunting. This means that in times when water conditions are poor or waterways overcrowded, tilapia will grow to smaller sizes so that the population number stays at a good level (for the tilapia population). This allows them to spread to substantial numbers and a lot of our native fish can’t handle this pressure on the food, water quality and the decimation of their own young.

Now, tilapia are in almost every freshwater waterway, so there are a number of spots to catch them where fish are plentiful. The easiest way to find tilapia is to look for signs, literally, as in many regions if a tilapia is spotted in the system, then warning signs will be posted on the public boat ramps. If the signs are there, so are the tilapia.

Now, this doesn’t mean they've been spotted in every pond or river, so there are two more ways to find them. The first is to look for nests. A tilapia nest will look like a circle of weedless bottom, almost like a weed. Often you will be able to see the larger parents holding in or around the nest. When they are doing this, they are very aggressive and will hit a lure. This is a reaction bite as they only attack other fish when they enter the nest, to protect the juvenile fish inside.

You can also find them by simply looking into the water. You will often be able to see tilapia cruising just below the surface. This is especially common in ponds where people will come to feed ducks and the tilapia have learnt that that is a free feed. So, once you've found an area with tilapia in it, you need to trick them into eating, which can be difficult.

Tilapia are mainly vegetarian, meaning it's not like fishing for perch and other predatory species, where you can simply use prawns and worms as these baits may not appeal to them. Depending on who you ask they will all say a different bait to use, however there are three main ones that we find effective. Peas, corn, and bread. Bread is only effective where people throw bread in the water to feed the ducks and other water birds. Peas and corn are better in places like small creeks and rivers. In some areas earthworms are the proven bait, however it’s worth remembering the vegetarian option of peas and corn, just in case they don’t work on the day.

There are two rigs that I use for tilapia and both are very simple. The first one is just a simple weightless hook. I generally use a small circle hook, around 2/0 size, which is a similar hook that I use for whiting fishing. I will normally run a swivel, rather than using an FG knot, the only reason for this is to add a little weight to aid with casting distance. The other rig that I use for tilapia is basically the same as the last one, except I add a small float. This is especially effective for younger kids, allowing them to see the hits a lot easier and hook them more effectively. Other than the float, the rig is pretty much the same.

I also run a very light leader for tilapia because they have no teeth, and they can be picky. So, I run 8lb Platypus Stealth FC Fluorocarbon Leader, which is about perfect. Any rod and reel set up is fine for tilapia. You don’t need a super expensive set up, just something that can cast light rigs and catch a fish. That's one good thing about tilapia, they are a great species to get kids into fishing and you don’t need an eight hundred dollar set up to catch them. A great starting option for kids is to select a combo from the Okuma Azaki Spin Combos or JAW Spin Combo range.

Tilapia are a real pest and we must do whatever we can to get them out of our systems. If you do catch one it is very important that you don't keep it or sell it, and especially don’t release it. It is illegal to do so. The best thing to do is put them in a bin or bury them well away from the water, in case rising water sees the eggs getting released.

Cheers, Nickfish

Note: Some information taken from the Department of Agriculture and Fisheries.