Do aquariums contribute to species extinction?
Almost four million households in Germany own at least one aquarium. According to animal rights activists, these people are contributing to the extinction of species. And animal rights activists would love to ban aquariums altogether. But why on earth?
Let's take the most popular ornamental fish, the cardinal tetra, of which 20 million are caught annually in the Amazon region and exported all over the world. Scientific studies have shown that the stock even of this fish, caught in extremely large quantities, is absolutely safe. At first, this sounds like defensiveness on the part of Brazil, but when you take a closer look at the biology of the fish, you’ll see their point. The animals produce millions of eggs that are released freely into the water and then protected from spawning predators in the bottom area between plants, foliage and branches. In the blackwater areas of the Rio Negro, where these fish mainly live, there is a permanent lack of food. If you cruise around there by boat in the evening hours, you don't even need mosquito repellent. There are practically no mosquitoes. With a pH value of 4, the water is so hostile to life that not even insect larvae and other plankton can survive there. In their search for food, the fish move into the flooded areas with their bellies already caved in and are caught there. The more animals are fished off, the more juveniles have a chance to survive. The food supply determines the size of the population here (study by Prof. Ning Labbish Chao 2012, Piaba project).
It is similar with marine fish. If a group of demoiselles (small colourful damselfish that are imported in very high numbers) is caught from a reef, juveniles have a chance to take their place among the branches of the staghorn corals. In the reef, it is not food scarcity but space availability that determines population density.
Animal rights activists always score points with the argument that 70% of all ornamental fish die on the way to Germany. If we put the actual figures aside for a moment, a guppy, for example, would not cost three euros but eleven euros in German pet shops - if the figures were correct. And protected species are banned from import. The law already helps here (IUCN Red List www.iucnredlist.org ; CITES). By the way, most of the fish listed in the CITES lists are not ornamental fish, but fish species such as sturgeons, which are imported and killed for commercial reasons for human consumption (caviar). In the field of freshwater aquaristics, only 4,800 of about 15,000 known species have ever been kept in aquariums. Of these, in turn, only 200-400 species are regularly kept. The first 10 species on the import hit lists already account for 80 % of all imported species. By comparison, the amount of freshwater fish consumed in Germany is about 70,000 tonnes per year. Of the 200-400 species reared regularly, 90 % are bred in captivity. Only 10 % are taken from the wild and imported offspring also count as "wild animal imports" (e.g. guppies from Singapore or Sri Lanka). Dr. Stefan Hetz, lecturer at the University of Berlin, has proven that the 70 % loss rate of imports referred to is fictitious (letter to Dr. Gebhart MdB, 16.01.14): "The paper cited in the text by pro Wildlife (Oliveira, S. R. , Souza, R. T. Y. B., E.G. 2008) itself cites two papers (Waichman, A.V. Pinheiro, M. and Marcon 2001) which also do not provide any mortality data verifiable on a scientific basis. As a result of this fact, the data in the cited work and thus in pro Wildlife must be classified as fictitious. The real and verifiable loss rates in fish imports (both freshwater and marine) are 1-3 %. If you would like to read a scientific study on this topic, we recommend the master's thesis by Matthias Homuth from 2010 at the Humboldt University of Berlin.
The importance of aquariums
Let's get back to the aquariums in the living room. How, for example, do we want to get children excited about nature, responsibility and animals if not through animal care itself? Through computer games?
Fish can grow significantly older in aquariums than they ever would in the wild where natural selection reigns. The predators which naturally decimate the population are simply not there. In public aquariums, such as the Berlin Aquarium, we find real Methusalems that wouldn’t have a chance in their natural habitats. All in all public aquariums provoke a lot of thinking that would never have arisen without the sight of the fish and invertebrates. In display boards and videos, visitors are introduced to ecological problems in the wild that they would never have learnt about on television. At the aquarium side, quite literally next to the affected inhabitants, they are absorbed and affected. They will now no longer simply throw the plastic bag into the river or the sea.
When selecting the species to be shown in German display aquariums (in Asia things look different again), meticulous attention is paid to the space requirements of the animals. Pelagic deep-sea sharks are not shown, whereas small shark species, which are also bred in large numbers, can be kept in conditions that are absolutely close to nature. Anyone who has been to a public aquarium and learnt how beautiful sharks are and then how they are in danger of being caught for use in shark fin soup will see the animals with different eyes from that moment on. But not everyone has the financial or time resources to travel to the regions where the animals live. And that's where aquariums step in - whether you have a piece of nature worth protecting at home, or learn about animals and their ecosystems from public display aquariums. It’s the best way to inspire people and convince them of the importance of nature conservation we have, and the best nature can offer too…