Have you ever stopped to think about where the fish that populate your aquarium have come from? Aquarium fish come from almost every corner of the globe. Every fish with its own habitat. These habitats vary from lakes to rivers and streams and even sometimes down to small puddles. It is these habitats that are crucial to the continued existence of these fish in the aquarium hobby.
There is such a wide variety of habitats from all over the globe, many of which are in third world countries. These countries have little concern for the places that the fish come from, even here in the US many times we make decisions that may help people but wipe out natural habitats. Probably the greatest single habitat destroyer in the US would be the creation of dams. Here in Oklahoma dams have created many problems for native fish species. The darter fish genus Etheostoma and Percina have taken the hardest hit. These fish are mainly located in Eastern Oklahoma in clear cool streams and rivers. Due to the many dams that have been created in Oklahoma some species of darter have been significantly reduced in numbers. The hardest hit species was Percina pantherina, the leopard darter. This species was heavily impacted due to the limited range it used to inhabit. Found mostly in the Glover River, Little River (in Southeastern Oklahoma) and the Mountain Fork River, it was seriously impacted by the creation of the Broken Bow dam on the Mountain Fork River and the Pine Creek dam on the Little River. This cut down the inhabitable portions of these rivers to the areas above Broken Bow Lake, the area above Pine Creek Reservoir, and the entire Glover River. This has cut the population down so much that even in what is left of their natural habitat their numbers are only estimated to be 5 per each hundred meters of river. They have become so rare that I would probably say that they are harder to find than a needle in a hay stack. Another area of great impact was the area above Hoover Dam. Many species were either driven into extinction or to the brink after the damís creation.
Of course this isnít the only problem that we have in the US that causes significant impact to fish populations. Some of the other problems that cause problems are of course water pollution (on the decline in the US), introduction of non-endemic (non-native) species of fish that either feed on native species or outcompete them for food, and finally logging.
These problems are however more frequent in third world countries. In the rain forests of South America extensive logging causes runoff of soil and other things into what was once very clean rivers. The has resulted in fish, which prefer pristinely clear and oxygenated water, to die off.
The most extreme case of massive extinction due to pollution is Lake Victoria. While there are other contributing factors to the annihilation of at least 100 species in the lake, the greatest has been the extensive run-off of fertilizers and toxic output of industrial plants upriver from the lake. This has caused algae blooms that are visible from space and a lack of oxygen at the deepest parts of the lake.
Introduction of non-endemic species has nearly wiped out native species of fish in Madagascar. One of the most dangerous and ravenous species of fish that has been introduced is not even stopped by lack of water. Imagine a fish that eats everything it sees, can grow to over 2 feet in length and will crawl for miles across dry land. As you can imagine, it is not something that is easily irradicated once it is introduced.
We as hobbyists actually have a great impact on the actions of people in third world countries. We can alter the attitude of native people about the habitats of fish species. One of the most successful programs to help try to reverse the problems with Lake Victoria has been public education. Aquariums and touring displays have been setup in towns around the lake to show the people the beauty of the fish that inhabit the lake, and the possible financial gain that could be accomplished by the export of fish species from the lake, once the populations in the lake can support it. So our simple hobby can be the difference in the fight to keep fish species alive. □