The other reason these crayfish are banned in Britain is because they can carry disease which could harm the native crayfish. Unfortunately, there are crayfish being sold illegally in Britain including the Mexican Orange Dwarf Crayfish, Cambarellus patzcuarensis. For more information on this issue, please see Practical Fish Keeping. It is still a problem.

Please only buy species legal in your area, and don’t release any pet fish or invertebrate into the wild.

Rosy Red Minnow, Fathead Minnow

This fish’s ideal temperatures are 10-21C, but it can survive much lower temperatures. The Fathead Minnow overwinters in Canadian boreal lakes. That said, it tends to have a high winterkill. Rosy Red Minnows grow approximately four inches in length. They are naturally greenish, but there is a very pretty pinkish-gold variety, which is why they have two names. You may be able to find this fish in your local aquarium store, possibly as feeder fish.

The Rosy Red Minnow can be a source of enteric red mouth disease for native european fish. Therefore, they should not be allowed to let them come in contact with each other.

Golden Orfe

The Golden Orfe grows to approximately 18 inches in length. While Golden Orfe are very pretty fish, they need to be kept in a school of at least three. They are also fussier about water quality than Goldfish or Koi, which is probably why they are less often kept than either Koi or Goldfish.

White Cloud Mountain Minnow

White Cloud Mountain Minnows only grow to 1.75 inches or less, making them the smallest of the fish discussed here. This fish is somewhat more sensitive to cold than other fish discussed here. It can survive down to 5C. Fortunately, their small size means that they can be moved into an aquarium for the winter without the sort of problems you would have doing the same thing with a large species like Koi.

The White Cloud Mountain Minnow is native to streams and prefers clean, well oxygenated water. It would probably make an excellent inhabitants for ponds with a waterfall or streamlike section, or for fountains.

Mosquito Fish (Gambusia affinis and G. holbrooki)

The Mosquito Fish is an interesting fish for very small ponds. It grows to 2.8 inches or less, and is more resistant to extreme temperatures of between 1.5-35C as well as to low dissolved oxygen. Of the two species, G. affinis is slightly more adapted to cold and holbrooki to heat. However, temperature tolerance varies depending on the population and its specific adaptations. Winter mortality of Gambusia tends to be high. Gambusia are closely related to the guppy, and are livebearers. They are probably most useful for very small ponds where the water can get very warm, such as container water gardens.

One problem to bear in mind with Gambusia especially is that they have a history of being an invasive species. This means that you must be even more careful never to allow them near natural water bodies.

Other Considerations

Before you buy any pond fish, remember that you must not introduce them into wild ponds or anywhere they might be able to get into natural waters. Some of the above fish, especially Mosquito Fish and White Cloud Mountain Minnows, are a bit too good at adapting to natural waters. The Mosquito Fish has been the cause of native fishes in New Zealand having local populations eliminated, and it is also a threat to native dragonflies and other aquatic invertebrates. They are also illegal in some areas. Check the legality of owning fish such as Gambusia or WC Mountain Minnows before introducing them to your man-made pond.

This is important for the fishkeeping hobby because a surprising number of fishes are still wild-caught from the Amazon, including such popular fish as Cardinal Tetras. This is not the only major recent drought. There was another large drought in 2005 described as a once in a century drought, and repeated droughts of this nature can hardly help but cause damage to the forest and its fish.

Given the predicted effects of climate change on the Amazon I was expecting something like this to happen. This year’s drought is probably partly caused by El Nino, but previous El Ninos didn’t cause this much devastation, and I blame the difference on climate change. See my previous post on the subject. However, I wasn’t expecting it this soon. There is more detail on the 2010 drought in this article by Heiko Bleher in Practical Fishkeeping: The Greatest Amazon River disaster in history.

Given the major problems aquarium fish in the Amazon are facing, you may wish to avoid buying wild-caught Amazonian fishes for the next year or so, unless you intend to breed them and have the skills to do so.

Unfortunately, it is also illegally wild caught in various places in Southeast Asia. Captive breeding, poaching, and smuggling are all encouraged by the high prices these fish bring.

Captive bred fish from Singapore usually come with an embedded microchip to prove that they are captive bred and prevent theft. Asian Arawanas are selectively bred for color, especially red or gold variations. There is a tradition in China that this fish, especially if red or golden, brings good luck to its owner. This is one reason for the fish’s popularity and high price.

Because of the prices these fish sell for, farming this species is quite lucrative and has been described as a ‘gold rush’ on the Arowana club website. A very good specimen may be worth tens of thousands of dollars.

Because Asian Arawanas are so expensive, they are sometimes smuggled. This means that if you are looking to buy one, you should check its papers and that it has an identifying microchip. It is all too easy to find stories about Arowanas being confiscated by customs officials, whether in boxes under legal items, or inside a dress being worn at the time. Problems you just don’t get with Neon Tetras…

Sources:

Arowana-care.com

Arowanaclub.com

CITES Convention Text

Fishbase.org

Ng, P., Tan, H. (1997) Freshwater fishes of Southeast Asia: potential for the fish trade and conservation issues. Aquarium Sciences and Conservation. Vol 1: 79-90

UNEP-WCMC. 6 March, 2007. UNEP-WCMC Species Database: CITES-Listed Species

It has been introduced to Indonesia (Sulawesi), the USA, Hong Kong, Taiwan, China, UK, Papua New Guinea, Guam, Taiwan, Thailand, and possibly the Philippines. This species has been nominated as one of the world’s top 100 invasive species. The method of invasion involves escapees from the pet trade as well as aquaculture. It is illegal to keep this fish in some countries, as well as in many US states.

Very cold water kills Walking Catfish, so if your area goes below freezing in the winter this fish should not become invasive even if some manage to escape. In many areas with warmer water it is often illegal to keep them without a permit. Even if they are legal in a warmer area, it is still very important not to let them escape from their tank.  Because of their ability to walk on land, the possibility of escape is much greater than with most tropical fish.  Make sure their aquarium has a strong and tightly fitting lid so that they cannot push it up and wander off.

Sources:

Global invasive species database. Compiled by Invasive Species Specialist Group (ISSG)

Brogan, Christine. 2003 Introduced Species Summary Project

Effects on the Amazon

The combined effects of deforestation and climate change are likely to result in significant drying of the Amazon Basin as well as disappearance of half or more of the forest, possibly within the next 20 years (Nepstad et al, 2008). The reasons for the drying are twofold: cutting the forest reduces the ability of the forest to create its own climate, and the warming climate means increased evaporation and more fires. The increased rate of fire reduces the area of forest further, making the situation worse. Loss of the Amazon rainforest would also accelerate climate change by removing one of the world’s most important carbon sinks.

Potentially, deforesting a large part of the Amazon, when combined with climate change is likely to result in a Savannah type ecosystem with much less water over most of the area now covered by the Amazon rain forest. Some models predict the loss of the Amazon from climate change even without deforestation (Harris et al, 2008). These changes are likely to be very difficult to reverse, and drying of the forest has already been observed (Li et al., 2008).

Effects on Fish

Put together, this means fewer streams in which fish can live and breed. Smaller streams will likely disappear entirely while water levels are lowered in larger streams and lakes. A possible preview of some of the effects might be the 2005 Amazonian drought. This drought was primarily caused by unusually warm sea surface temperatures in the tropical north Atlantic. In 2005, streams disappeared and lower water levels in larger streams and lakes caused fish kills as well as increased fire (Marengo et al, 2008).

If these changes occur as predicted by current models, the area of habitat available to the fish species that depend on the forest will be vastly reduced, and many species will probably go extinct. Those that don’t will be scarcer they are now and will need to be bred in captivity if they are to continue appearing in hobbyist’s fish tanks. Considering how many aquarium fish species come from the Amazon, this is likely to have a major impact on the hobby.

What Can We Do?

This is not a scenario likely to be attractive to most fish keepers, but there are things that can be done to make the situation less devastating. The two key variables are climate change and deforestation in the Amazon basin. Therefore, all the usual methods of reducing climate change apply. Information on how to reduce climate change, and links to other informative sites, can be found here, and at many, many other sites on the Internet.

Reducing deforestation in the Amazon is a little more tricky for those of us who do not live in South America. More about the problems plaguing the Amazon, as well as possible solutions to these problems, can be found here.

References:

Harris, P. Huntingford, C., Cox, P. (2008) Amazon Basin Climate under global warming: the role of the sea surface temperature. Philosophical Transactions of the Royal Society 363: 1753-1759

Li, W., Fu, R., Robinson, I., Juarez R., Fernandez, K. (2008) Observed Change of the standardized precipitation index, its potential cause and implications to future climate change in the Amazon region. Philosophical Transactions of the Royal Society 363, 1767-1772.

Marengo, J., Nobre, C., Tomasella, J., Cardoso, M., and Oyama, M. (2008) Hydro-climatic and ecological behavior of the drought of Amazonia in 2005 Philosophical Transactions of the Royal Society 363,1773-1778

Nepstad, D., Stickler, C., Soeres-Filko, B., Merry, F. (2008) Interactions among Amazon land use, forests and climate: prospects for a near term forest tipping point. Philosophical Transactions of the Royal Society 363, 1737-1746

The black ruby barb is bred in captivity in Sri Lanka as well as being wild caught for export (Ekaratne, 2000). It is also bred in hobbyist’s tanks and instructions for breeding can be found in such places as Mongabay.com. I am not certain to what extent it is bred commercially outside of Sri Lanka.

References:

Ekaratne, S. 2000. A Review of the status and trends of exported ornamental fish resources and their habitats in Sri Lanka. Published by Y.S. YADAVA for the Bay of Bengal Programme.ftp://ftp.fao.org/docrep/fao/007/ad920e/ad920e00.pdf

Fishbase.org

Butler, R. San Francisco, CA Mongabay.com. 1999-2008. Retrieved 09 March 2009 http://fish.mongabay.com/species/Puntius_nigrofasciatus.html

Pethiyagoda, R. 1996. Puntius nigrofsciatus. In: IUCN 2008. 2008 IUCN Red List of Threatened Species.www.iucnredlist.org. Downloaded on 03 March 2009.

Sinharaja forest reserve. World heritage sites. United Nations environment programme and the world conservation union monitoring center. Appears to have been written post-2003. Retrieved 4 March 2009.

http://www.unep-wcmc.org/sites/wh/pdf/Sinharaja.pdf

Unfortunately, guppies have become an invasive species in Asia, Australasia-Pacific, Europe, North America, and South America. They were intentionally introduced to many of these areas in order to control mosquitoes, but some feral populations are probably descended from escaped pets (Global invasive species database). 

References:

Fishbase.org

Global invasive species database. Compiled by National Biological Information Infrastructure (NBII) and Invasive Species Specialist Group (ISSG)

http://www.invasivespecies.net/database/species/ecology.asp?si=683&fr=1&sts=

Poeser, F., Kempkes, M., Isbrucker, I. 2005 Contributions to Zoology. Description of Poecilia (Acanthophacelus) wingei, n. sp. from the Paria Peninsula, Venezuela, including notes on AcanthophacelusEigenmann, 1907 and other subgenera of Poecilia Bloch and Schneider, 1801 (Teleosti, Cyprinodontiformes, Poeciliidae) http://dpc.uba.uva.nl/ctz/vol74/nr01/art07

Hotsprings in cold areas that contain endemic species are especially vulnerable to invasion because any species already present are present only in a small area where they can easily be overrun by an aggressive species imported from elsewhere. Also vulnerable are island species, endemic lake species and others with small natural habitats.  These are vulnerable for the same reasons as hot springs. Species whose habitat has been disturbed are also vulnerable. Habitat disturbance often occurs along with invasive species problems, since the already changed ecosystem is likely to provide opportunities for invasive species that arrive in the area and many of the native species are stressed by the changes that have occurred in their natural habitat.

This is the main reason why it is important not to release ornamental fish into the wild. There are also a couple of other reasons. If the environment is unsuitable for your fish, they will die. This is cruel to your fish. There is also the possibility of them introducing exotic diseases which transfer to native species.

References:

Global Invasive Species Database               http://www.issg.org/database/species/ecology.asp?si=89

Catch per unit effort measures the number of fish caught per unit of effort. Units of effort are often defined by the number of people or number of ships fishing, or the total amount of time spent fishing, or some combination of the above. A lower catch per unit effort means that it takes more effort to catch the same number of fish. In this case, this could indicate that there is overexploitation occurring, as this has been one of the indications that a fishery is going into decline in major food fisheries such as the Atlantic Cod (Icthyology notes, UVic 2004). However, judging from Chao and Prang’s information, there does not appear to be immediate danger to the Cardinal Tetra’s survival. I hope that they and the rest of project Piaba will pay attention to the situation so that the Cardinal population does not decline severely.

The hopes of the project are that extraction of fish from the forest can prevent deforestation by providing an alternate livelihood, and that this can be done in a sustainable manner. To accomplish this, they provided information about ornamental fish trade to the people of Barcelos. They have also done some basic research on the ecology of the ornamental fish in the area, including some long-term monitoring (Chang and Prang, 2002). This is unusual in the ornamental fish trade and valuable, because there is too little research into ornamental fish populations in the wild.

Overall, it appears a useful initiative that it would be useful to copy elsewhere, although I would like to see more independent research on ornamental fishes conducted by a group that is not connected so closely to the ornamental fish trade, and some attention paid to the decreasing catch per unit effort.  Declining catch per unit effort alone is inadequate to fully determine what is occurring with a population (Maunder et. al., 2006), but it is a very bad sign. They probably need to lower their catches to make the fishery truly sustainable.

Chao, N., Prang, G.(2002). Decade of Project Piaba: Reflections and Prospects. Official Publication of Ornamental Fish International 39

http://www.neaq.org/scilearn/research/pdf/14__.pdf

Gerstner, C., Ortega, H., Sanchez, H.,and Graham, D. (2006) Effects of the freshwater aquarium trade on wild fish populations of the peruvian amazon. Journal of Fish Biology. 68:862-875

Monder, M., Sibert, J., Fonteneau A., Hampton, J., Kleiber, P., Harley, S. (2006) Interpreting catch per unit effort data to assess the status of individual stocks and communities ICES journal of marine science 63: 1373-1385

Reimchen, T. E. (2004) Icthyology class notes, University of Victoria