As usual, I was staying in Thailand in June 2019.
I was visiting a place called Sangkhlaburi in Kanchanaburi province in western Thailand.
This place has been my favorite place to visit ever since I started fieldwork in Thailand.
It is rich in nature and has many interesting types of freshwater fish, insects, and plants.
It had become a habit for me to always use this place as my base and stroll around the surrounding fields.
It's a place I visit several times every year, so I've recently made a lot of acquaintances there.
Casual conversations with such people can give you hints for exploring the field.
After all, information from local people is extremely important.

This time, I got some interesting information when my partner Ton was visiting a fish shop where he always buys fish.
The fish live in a village next to the Sangaria River, the largest river in Sankkhlaburi.
For about 10 years now, Tong has been purchasing fish from Myanmar.
For people living along these borders, the borders seem like they don't exist, and they can travel back and forth between Thailand and Myanmar without using passports.
I always visit his house and ask him to show me the fish he stocks.
This work is essential because you can sometimes find quite rare fish.
I noticed that there were quite a lot of roaches in one tank.
It's a pretty common roach around here, and it's a small, cute species that grows only 3 to 4 centimeters.
As I watched Roach, the forager pulled out his smartphone and showed me a video.
This small roach appeared to be running up the steps in large numbers in the field.
I have seen gobies and shrimp swimming upstream before, but this was the first time I had seen roaches swimming upstream.
When I asked about it, I was told that this is how a large number of roaches were caught swimming upstream.
I see, if you cast your net in a place where this many people are gathered, you will be able to catch them all in one fell swoop.
Both gobies and shrimp migrate upstream at night, when they are rarely attacked by predators.
I wondered if this roach only migrated upstream at night, so when I asked about it, I was told it was during the day.
Isn't it said to be a nearby trickle about 10 minutes from here? !
Naturally, I would like to see how it swims upstream, and I would also like to photograph it.
Needless to say, I was immediately guided to the trickle.

I was a little skeptical as to whether they were really going upstream in the middle of the day, but I managed to get through the bushes and was guided to the spot.
When we arrived at the trickle, we were told to be quiet and try to make as little noise and vibration as possible.
Of course, in such a delicate scene, stimulation is a no-no.
When I peered gently into the stream, I noticed that many roaches had gathered in the pool below the 2-meter step.
Some of them jump against the current and swim upstream.
For the time being, I decided to postpone taking pictures and observe the situation.
If they have suction cups like gobies or can suck with their mouths like sea breams, it wouldn't be difficult for them to swim upstream against the current.
It also makes sense that if they have the physical strength that large salmon and other fish have, they can fight against the current.
However, what is currently swimming upstream in front of me is a small roach, about 3 cm long, that does not have any means of latch.

As I observed them, it seemed like their strategy was to choose as much as possible, such as hollows in streams with no water, and slowly climb up little by little.
The way it bounces up and down against the current is so brave that you'll never get tired of watching it.
It's not quite a waterfall, but the flow over the two-meter step is fast, and the water sprays quite a bit.
The footing was also poor, making the situation unsuitable for photography.
As expected, a waterproof compact digital camera cannot handle this situation.
Unless you have a single-lens reflex camera equipped with a macro lens, it is impossible to stop moving and focus.
I try to take some photos by blocking the water splash with some plastic, but the subject is small and moves quickly.
Moreover, it is extremely difficult to take a good photo because the water flow and splashes cover the subject.
Since I don't have time to check while taking pictures, I decided to release the shutter at the point where it doesn't work and check the image later.
More than I expected, I was hampered by droplets and other factors, and I wasn't able to get a satisfactory cut.
The photos I will introduce here are the ones I managed to take under these circumstances.
Having said that, I just shot the photo with the equipment I had and without any mental preparation.
Looking at it again now, I find it quite unconvincing.
To be honest, I would like to get the right equipment for the situation and try shooting again.

I would like to visit the same place during the same season this year and try again.
However, nature is fickle, and there is a high possibility that you will never find yourself in the same situation.
Photographers of nature must be prepared not to miss a once-in-a-lifetime opportunity.
By the way, the scientific name of this climbing roach is Paracanthocobitis maeklongensis.
As the species name suggests, it is a small roach that inhabits the Maeklong water system in western Thailand, and is the most commonly seen species around Sankhlaburi.
It is an easy species to keep, so I would like to see if this upstream behavior can be observed in captivity.