Freshwater GTs? Juvis? No, fully grown!

This was end of what sounded like a florally ludicrous conversation between two chaps I was fishing with. It was a long time ago, the fishing was good that day so I never again considered the statement.

Until recently that is, when a friend sent me a video clip of trevallies swimming around a freshwater fish tank. He’s a keen fisherman but a serious tank aficionado! I get some really cool clips from Chase once in awhile but this was rad. And it sparked the memory that brought back that conversation on a fishing trip about freshwater giant trevally.

So I waded into trusty Google to find some answers.

Turns out that most trevally can be ‘converted’ to freshwater and are readily available on sale the in world of exotic fish trading. Although I’m nervous to consider what the diet of tank bred GT would be be! The trusty interweb abounded with stories of brassies, bigeyes, goldens and even small Geets living happily in freshwater tanks all over the world.

But it’s a place in the Phillipines that really is the centrepiece to the whole freshwater GT story. Lake Taal, not far south of Manila, was once upon a time was a salt water lake system connected to the sea by way of big channel. No doubt the looseness of the fishing in a tropical salt water lake in those years is something to dream about. Anyway, the story goes, recorded by a Priest in 1754, that an eruption of Volcano Taal that spanned almost six months effectively shut off the lake to the sea. Over the following years, the tropical monsoons so caused the lake to desalinate, eventually becoming completely fresh as the salt water filtered to the ocean. But the GTs, and all the other salt water life remained…

Strange Sight: A GT statue on the edge of a freshwater lake…

Thomas Hargrove wrote of Lake Taal*: “Lake Taal’s marine life draws me back, almost like those mysterious towns that sank so long ago. Her deep waters are classified as fresh today—but Taal protects life that Nature intended only for the sea.”

Clearly this is a place that is unbelievably unique in terms of bioverse history. There are a variety of saline species that have adapted to freshwater life and the area is steeped in an obscured history that goes beyond the time of the Spanish colonies.

I searched long and hard to find photos of the actual fish but the interwebs wasn’t very forthcoming. There were, however, many posts and articles that referred to the lake GT – the maliputo loob – and in particular an interesting research paper, published in The Journal of Nature Studies** that shed a bit more light on the now mythical (at least in my mind) freshwater GT.

It would appear that the ‘true’ Maliputo – which is actually referred to as Maliputo loob*** – is catadromous (opposite to anadromous in that it travels to salt water for reproductive purposes before heading back to the lake). The fish swim down the now open Pansipit River and spawn in the estuary area. And unlike its salty cousins, it doesn’t seem to get very big.

The Pansipit River
Another statue of Maliputo in San Nicolas Municipal Hall

Unfortunately today it seems that, like in so many other stories of the wild and amazing, the Maliputo is under severe pressure. It is a prized delicacy and features on menus across the lakeside town of San Nicolas and greater area of Lake Taal. This resulting in heavy fishing and netting practices in the Pansipit River that target the migrating spawners.

But this is hope too. There is mention that a breeding program in the barrio of Botong has successfully bred Maliputo in captivity. And another positive point is that it sounds like the netting practices in the Pansipit have also been stopped by authorities in a move to conserve this unique ecosystem!

Maybe Lake Taal’s freshwater GTs will survive yet…

* The Mysteries of Taal, A Phillipine Volcano and Lake, Her Sea Life and Lost Towns, Thomas R. Hargrove
**Alaira, S. and Rebancos, C. 2014. Maliputo (Caranx ignobilis Foorskal) Fish Cage Farming Practices among Selected Operators in Taal Lake, Batangas, Philippines. Journal of Nature Studies 13 (2):25-40
*** Maliputo referes to GT. loob means from the inside (inside the lake), while labas means from the outside (the sea).

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