Sounds weird? If so you haven´t heard about the ”fish mail box” in Inada Park, Kawasaki, Tama River in Japan near Tokyo. The ”fish mail box” is a 7 meter by 4 meter large concrete water tank that have been placed along the river to give people a place to drop unwanted fish. The goal of the fish box is to prevent people from releasing fish into the river, since foreign species can wreck havoc with local ecosystems.

People are encourage to call before they drop off their pets as fish can die from the shock if not acclimatized correctly, but it is is permitted to just drop off fish as well. People are also encouraged to drop off tropical invasive species they catch in the river in the fish box.

The fish left in these fish boxes are cared for by Mitsuaki Yamasaki, 51, the head of a local river fish association, before they are placed in new homes. The box is receiving about 10,000 fish a year ranging from small fish to large gars.

The Tama River has seen a lot of new species released in it in recent years during which the aquarium hobby has become even more popular in Japan than before. This has in no small part to do with the movie “Finding Nemo”, even if the increase in popularity started before the movie was released. More than 200 species of foreign tropical fish have been found in the Tama River ranging from typical aquarium fish such as guppies and angelfish to less frequently kept creatures like piranhas and arowanas, earning it the nick name the Tamazon River. Some of the tropical species have established breeding populations while others haven´t, but most species can survive the winters by staying near water treatment areas along the river.

Mitsuaki Yamasaki and other members of the local river fish association are afraid that breeding populations of gars will establish themselves in the river since more and more gars are sold and they have been found in the river. Gar species are predatory fish that could have a severe negative impact on native fish such as sweetfish . Gars are likely able to establish breeding populations in a river with the conditions of the Tama River.

It can not be denied that with over 10,000 fish received by one of these fish boxes since it opened the initiative could aid the struggle to prevent invasive species from getting a foothold in local waters, and it might be an idea that deserves being tried in other problems areas around the world, such as Florida. The only question is if projects like this could work with out the devotion and support from people like Mitsuaki Yamasaki, people who are really passionate about what they do.

Any one interested in or planning to start a similar project somewhere else is very welcome to contact us here at AquaticCommunity as we would love to document your work getting the project of the ground and running it. Leave a comment in the commentary field or send an e-mail to admin@aquaticcommunity.com.

The gar family, famous for containing the largest fresh water fishes in Mexico, is currently at risk of becoming extinct – something which Mexican researchers are working hard to prevent.

“This fish is native to our country and the United States”, Doctor Eduardo Mendoza Alfaro explains. “Currently, its populations are threatened due to excessive hunting, — for there are no rules that regulate its fishing — urban expansion, pollution, and particularly the dams´ construction, which caused the destruction of their breeding grounds. These factors led this species to reduce to only forty adult specimens in the country — in inventory and considered national patrimony.”

Doctor Eduardo Mendoza Alfaro*, a member of the ‘Eco-physiology Group,’ from the Universidad Autonoma de Nuevo Leon’s (UANL) School of Biological Sciences Ecological Department, is currently researching gar reproduction and diet in order to find ways of efficiently raising gars in captivity. The team also works with several other types of endangered fish, but the gar – which can reach a length of three meter and is highly esteemed by sport fishers – is arguably the most iconic.

Lepisosteus platostomus – Shortnosed gar, Copyright www.jjphoto.dk

One of the hurdles that must be overcome to ease gar raising in captivity is how to distinguish males from females. In a reproductive facility you want to keep an ideal sex ration – with gars this is four males for each female – but this is difficult to accomplish without reliable sexing methods.

“We could not identify females and males, because, morphologically, they are

Identical”, says Dr Alfaro. “Even though most of the fish can be cannulated in order to know their gender and maturation status, for gar is not the same process, that is what represents

the first obstacle for scientifics when they were carrying out the reproduction

studies and establishing fish’s gender. Most of the fish can be cannulated by introducing them a catheter in the oviduct in order to take the oocytes (ovules). However, this process cannot

be carried out with the gar. They are so primitive fish, which date since 189 million years ago and their urinal tract which ends with the oviduct in a kind of sewer that cannot allow the

cannulation.”

To overcome the problem, Dr Alfaro and his team devised a new technique based on a molecule known as vitelogenine. Vitelogenine is present only in females from puberty and onwards, and can be used as a biochemical marker.

First, the team purified the molecule. Then, they created antibodies against the molecule for recognizing and quantifying it.

“Currently, we got an extremely sensitive method which allows us to dose this molecule with only a small sample of fish’s skin mucus, says Dr Alfaro. “So, we not only identified if it is a female or a male, but we can follow up females’ sexual maturation.”

Gar facts

· The gar family evolved during the cretaceous.

· A gar can weigh up to 220 lbs.

· The gar is a predatory fish with an elongated jaw. It is sometimes referred to as alligator fish due to its resemblance to the predatory reptile. It has numerous sharp teeth and a body protected by hard scales.

· Gars spawn in swamps during the wet season and destruction of wetlands poses a problem for them.

· In the wild, several males follow the female wanting to fertilize her eggs as she deposits them.

· Mexico is the world’s leading gar specimen producer.

*Roberto Eduardo Mendoza Alfaro is a professor at the UANL´s School of Biological Sciences Ecology Department in Leon, Mexico.