Invader Knife Fish: Chitala chitala at Laguna de Bai

Our lakes and rivers are being invaded. This time the invader is the Chitala chitala or more commonly known as the Knife Fish Most people will be familiar with or would have probably seen it inside an aquarium. Now it is at the latest poster boy of Invasive Species in the Philippines. As can be seen in a sample of headlines from media.

Alarm raised over knife fish invasion in Laguna de Bay

Pamalakaya blames LLDA for spread of knife fish

Knife Fish invades Laguna Lake

Philippine seeks to blunt knife fish invasion

DENR studying use of turtles vs Knife fish

For the moment the Knifefish has been branded as the latest invader to our local lakes and rivers replacing the Janitor fish or an armored catfish or a suckermouth sailfin catfish from South America known before as the Plecostomus but now is Pterygoplichthys. A reading of the news reports reveal some inaccuracies – like stating that the Janitor fish is a an African catfish not South American, although I think we have been invaded by an African Catfish as well – and possible recommendations that maybe worsening the problem rather than solving – like introducing soft shell turtles Pelodiscus sinensis to kill the knife fish population – thereby just replacing the problem species with another one in our lakes and rivers.

Is this a new phenomenon or have we been through this before? Do we really have to formulate new policies and plans or do we just have to re-tool and implement plans formulated before?

In May 21 to 22, 2001, a Seminar workshop was held to discuss, strategize and recommend measures to be taken to tackle Invasive species. An article written by Rexie Jane Parreño entitled,
THEIR BIODIVERSITY AND MANAGEMENT IN THE PHILIPPINES: Tackling the Issue on Invasive Species can be found online here.

The seminar-workshop was organized by the ASEAN Regional Center for Biodiversity Conservation or ARCBC in collaboration with the Protected Areas and Wildlife Bureau of the Department of Environment and Natural Resources or DENR in celebration of the International Day for Biological Diversity. The workshop recommended the following:

Conduct pilot test before introducing alien species to determine their beneficial and invasive attributes.

Enforce rigid inspection and quarantine regulations to prevent uncontrolled transfer of pests when importing logs and reforestation species.

Monitor identified alien species invasive to indigenous and endemic species.

Monitor developments relevant to altered species (genetically modified organ- isms or GMOs).

Use of invasive alien species instead of alien invasive species.

Mobilize interagency effort through task forces involving the DENR, Department of Agriculture, NGOs, other government agencies, communities, private entities and other related agencies.

Improve existing policies and other regulations related to invasive alien species and formulate new policies.

Enhance public awareness and encourage advocacy campaigns by making people understand the impact of such species and involving them in action plans.

Conduct more researches on invasive alien species and dis- seminate results to the public and other appropriate bod- ies.

Establish a baseline data on endemic/indigenous and alien species

The participants were told that the recommendations and agreements will be forwarded to the Philippine Council for Sustainable Development through the relevant sub-committee, the House of Representatives through the Committee on Biodiversity and to the Office of the DENR Secretary through Undersecretary Ignacio.

The workshop – seminar discussed different types of Alien invaders. For Aquatic invaders the following were listed – these were Alien Aquatic species introduced into the Philippines (Most of these were mentioned by Dr Rafael Guerrero and Ravindra C. Joshi in their respective papers on invasive species- Invasive Aquatic Animals and Invasive Alien Species: Concerns and status in the Philippines

The Thai catfish or Clarias batrachus,
The Golden Apple Snail or Pomacea canaliculata;
The African catfish or Clarias gariepinus;
The White Goby or Glossogobius giurus;
The Eleotrid or Hypseleotris agilis;
The Mosquito Fish or Gambusia affinis;
The Jaguar Guapote or Parachrmis managuensis (?)
And the Janitor Fish or Pterygoplichthys pardalis and P. disjunctivus

I wonder why the Tilapia was not include? Clearly this was an introduced alien species. Like the Golden Apple Snail and its pink eggs it was brought in as a food source from the United States in the 1980s and it displaced the native kuhol or Pila Luzonica. The Thai catfish was also introduced for food and displaced the native Clarias macrocephalus. Other species that maybe but hopefully not included in the list would be the Mekong Kanduli or the Pangasius hypopthalamus; the Giant Snakehead or the Channa micropeltes ; and even the Fortune Lobster also known as the Procambarus clarkii.

Incidentally, study was recently releases showing that the species of Janitor fish have been cross-breeding,

DNA barcodes of the suckermouth sailfin catfish Pterygoplichthys (Siluriformes: Loricariidae) in the Marikina River system, Philippines: Molecular perspective of an invasive alien fish species Joycelyn C. Jumawan1,3*, Benjamin M. Vallejo2, Annabelle A. Herrera3, Corazon C. Buerano3 and Ian Kendrich C. Fontanil

Of course, we, Man introduced them to our waters. The more popular belief is that these were introduced by aquarium hobbyists who grew tired of them or could not support these pets as they outgrew their tank. Another possibility and less popular is that these organisms could have been bred near the lakes and rivers – in fish farms and fish ponds. They may have escaped during a storm or when water was changed. What I fear and is a possibility is that they were cultured in fish cages or fish pens -even for grow-out purposes.

In the workshop one of the things discussed was the need to create public awareness the ecological, economical and social impact of invasive species. It and their recommendation of that workshop more than a decade ago is still valid, very much so.

So how do you stop the invasion of the Knife Fish? One can hunt them down and eat them . It is considered a delicacy. You could introduce another predator but done without a study is haphazard and could lead to bigger problems. Another suggestion would be to put limits and impose inspection on fish farms and ponds near the rivers and lakes but then again this particular solution is something that should have been before,a long long long time ago.

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