is this a tilapia?

[vyno9]

I was down at my local river the other day, searching for native rainbow fish and hardyheads, when I caught a couple of fish that I couldn't quite identify. They don't resemble any native species I'm familiar with, and I'm pretty sure they're some type of cichlid. If they are indeed tilapia, I know the law is clear on how to handle them. But before taking any action, I wanted to get some input from those with more experience with cichlids.

As for adult tilapia, I can usually identify them without issue. However, these fish appear to be juveniles, which is why I'm having trouble making a positive ID.

[medic23]

I'm fairly confident that these are indeed tilapia mossambicus. The body shape and coloration are quite consistent with this species. I've had some experience with cichlids and these little guys seem to match the juvenile tilapia profile.

[vyno9]

Thanks medic23, I was actually thinking more along the lines of Redbelly tilapia T. zilii myself. I'm curious, do all tilapia species develop those "egg" or tail spots, and if so, is that something the juveniles have from the start or is it something that comes later as they mature?

[finestic]

Many years ago, my kids brought home a juvenile tilapia, and I had no idea what it was - just a fish. The picture you posted, vyno9, looks exactly like it. We kept it, named it George, and put it in the pond with a pair of convict cichlids. As George grew, it developed four big black spots along its body and an ugly, muddy, slimy green color. But despite its looks, George was friendly and would take food right out of your hands.

A friend eventually told us we had an illegal fish, and the potential fine was staggering - $50,000. I was torn - I couldn't bring myself to kill George, but I knew I had to do something. In the end, I kept George, but made sure to keep it a secret. Not long after, George passed away, which was a blessing in disguise.

Now that I know what tilapia are, I often catch them in the creeks when we're out looking for shrimps. It's usually just the small juveniles that get caught in the nets. With a heavy heart, I destroy them - it's a hard thing to do, but I know it's the right thing.

[vyno9]

Thanks Better Is Betta. I've seen mature tilapia before, but never juveniles. And I've never seen them in the Fitzroy river. I guess I was only able to catch these two because it was nighttime and I had a bright torch. The government and bodies like DPI really need to make it easier to identify potential pest species, especially the juveniles. They mostly only show the fully mature specimens, which isn't much help when you catch something that looks completely different. I wonder how many people have unknowingly taken home an illegal juvenile fish just because it doesn't resemble the mature pest species. At least I knew it was likely a cichlid and potentially an invasive pest.

One of the tilapia is struggling and I don't think it'll last long. It was covered in fungus when I caught it, probably due to the recent cold snaps. They don't like cold weather, after all. The other one looks healthier, but it's also got a few small fungus spots on its tail. Before they go, I'll try to get some better photos, just for the record. Even if I never know for sure which species of tilapia they are, it's worth documenting.

[goldminer]

I've never encountered tilapia in the Fitzroy river before, and I'm still trying to wrap my head around it. Have you considered reaching out to the DPI about this, vyno9? I think it's worth bringing to their attention. We've got our own set of problems here, European carp being a major one.

[vyno9]

It's no surprise to me that tilapia can coexist with wild carp, those two pests seem to thrive together, unfortunately at the expense of our native species. Just another example of how invasive species can wreak havoc on the ecosystem. The other small fish in these shots, a gambusia, is also on its way out, another pest that's got to go.

[medic23]

Thanks Dr Rob, I was leaning towards Redbelly tilapia T. zilii, but I appreciate your input. I've got a question about the tail spots - do all tilapia develop those, or is it specific to certain species? And if so, do the juveniles typically have them, or is that something that comes later as they mature?

[vyno9]

It seems like tilapia are going to be a permanent fixture in our water systems, unfortunately. Whether they were introduced on purpose for pest control or by accident when owners dumped them, thinking it was better than killing them, they're here to stay. As prolific breeders, they quickly grow to a decent size, so I hope that larger fish like barramundi will make a meal of them while they're still small. It's a shame that tilapia are causing so much harm to our native fish, and personally, I'd much rather see a variety of rainbow fish, gudgeon, and blue eye trout thriving instead of these pests.