Fish Expedition Day 7 - Why do we need to kill the fishes?

There have been some comments on social media that we should not kill the fishes for the Singapore fish library. Instead, the suggestion is that we should just keep photos or even just have paintings of fishes in the Singapore fish library.

Scientists working on the fish library.

Here's more on why this is not possible if we want to have accurate science that helps protect fishes and humans that eat fish and need clean water. And how having a fish DNA library actually means scientists do not have to kill as many fishes in the future.  Much fewer fishes are killed for the fish library, compared to the many many many more fishes killed to be eaten or by pollution or other ways that do not add to science.

Today is a day of rest for the Singapore Marine Fishes Expedition. I'm going to take this time to explain why we need actual real fishes for the Singapore fish library.


Gorgeous paintings of fishes and amazing photos of fishes are important for helping people to know about our wonderful fishes and to love and protect them.

However, in order to do proper science, we need actual real fishes in the fish library.

Just as we need books in the library that can be opened and read, we need specimens of actual fishes in the fish library, as only these fishes can be 'read' by scientists.

Having a painting or a photo of a fish, instead of the actual fish, is like having a painting or a photo of a book instead of the actual book. We can't read a painting of a book, or a photo of a book. We can't 'open' the pages to 'read' the information if all we have is a photo or a painting of the book.

How do scientists 'read' a fish like reading a book? To accurately identify a fish, close study is needed by experts (who know what to look for) of very small features of an actual fish. Often, a strong microscope is needed as the features are not visible to the naked eye. Accurate identification is hard if not impossible to make from just photographs. Especially if the photograph is not detailed enough, and does not include the features that are needed. Some fishes are only accurately identified by internal parts. During the Expedition, fishes in the library will also be X-rayed.

A fish being examined under a microscope during the Expedition.

Another vital aspect that can only be 'read' from an actual fish is DNA information. DNA Barcoding is a reliable method to detect fishes that look very different but are actually the same species. Or a fish species that changes drastically, for example, parrotfishes can change their sex as they mature with drastic changes in patterns and colours. But their DNA will remain the same.

DNA being taken during the Expedition.

Having a DNA fish library actually means scientists do not have to kill as many fishes in the future: eDNA allows scientists to identify the fishes found in an area simply by sampling the water from the area! How is this achieved?! Mucus, scales and other traces of fishes in a water sample provide DNA that can be compared to the DNA in the library. This method is known as ‘environmental sampling (eDNA)’. It is an efficient way to biomonitor the fishes living our marine areas.

All these cannot be obtained from a painting or a photograph.

Which is not to say that photos are not useful. In fact, high resolution photos are among the data meticulously captured about the fishes in the library. Before the photo is taken, the fishes are painstakingly prepared so their fins and other body features are captured. Effort is made to retain the live colouration of the fishes. Taking high resolution scientific photos is a tiring and back breaking task.

Carefully preparing a Stonefish for photography.

Please understand, all the volunteers and experts involved in building the fish library hate killing animals as much as anyone. We do not wantonly kill the fishes. The fishes found during this Expedition are euthanised as painlessly as possible. The specimens are handled with respect and care.

This is compared to the many many many more fishes that are killed to be eaten or by pollution or other ways that do not add to science.

It is very hard work building the fish library. This massive effort involves scientists, experts and volunteers, divers, anglers, intertidal surveyors. All of us do it because we believe it will be good for all the fishes. We want to better understand details of the fishes, so we can better protect them.

The intertidal team start work before dawn,
switching to back breaking netting after sunrise.

The fish library is good for humans too.

One of the 'pages' of a fish that is 'read' by experts during the Expedition, is taking samples of the guts of the fish. This will be closely studied to better understand the microbes that affect fish health in our waters. This can provide important information for our local aquaculture industry so they can raise healthy fish for all of us to eat.

The gut of a Seabass being sampled for microbes.

We cannot gather this information without killing fish.

All specimens collected during the Expedition will be kept at the Lee Kong Chian Natural History Museum. Well preserved specimens can last for decades. So scientists can answer important questions that we may not even know to ask right now. In an era of climate change, having a library of such information is vital.

These fishes will not have died in vain.

I hope this explains what the Expedition is trying to achieve. And why photos and paintings of fishes are not enough to do the science needed to protect fish and help humans.

More about the Singapore Marine Fishes Expedition 2019 with daily and other updates are posted here.