AY Honors/Fishes/Answer Key

A freshwater aquarium.

Fishkeeping is a popular hobby concerned with keeping fish in the home aquarium or garden pond.

The hobby can be broadly divided into three specific disciplines, freshwater, brackish, and marine fishkeeping. Freshwater fishkeeping is by far the most popular branch of the hobby, with even small pet stores often selling a variety of freshwater fish, such as goldfish, guppies, and angelfish. While most freshwater aquaria are set up as community tanks containing a variety of peaceful species, many aquarists keep single-species aquaria with a view to breeding. Livebearing fish such as mollies and guppies are among the species that are most easily raised in captivity, but aquarists also regularly breed numerous other species, including many types of cichlid, catfish, characin, and killifish.

Marine aquaria are generally more difficult to maintain and the livestock is significantly more expensive, and as a result this branch of the hobby tends to attract more experienced fishkeepers. However, marine aquaria can be exceedingly beautiful, due to the attractive colours and shapes of the corals and coral reef fish kept in them. Temperate zone marine fish are not as commonly kept in home aquaria, primarily because they do not do well at room temperature. An aquarium containing these coldwater species usually needs to be either located in a cool room (such as an unheated basement) or else chilled using a refrigeration device known as a 'chiller'.

Brackish water aquaria combine elements of both marine and freshwater fishkeeping, reflecting the fact that these aquaria contain water with a salinity in between that of freshwater and seawater. Fish kept in brackish water aquaria come from habitats with varying salinity, such as mangroves and estuaries and do not do well if permanently kept in freshwater aquaria. Although brackish water aquaria are not overly familiar to newcomers to the hobby, a surprising number of species prefer brackish water conditions, including the mollies, many gobies, some pufferfish, and virtually all the freshwater soles.

Fishkeepers are often known as aquarists, since many of them are not solely interested in keeping fish. Many fishkeepers create freshwater aquaria where the focus is on the aquatic plants rather than the fish. Though known as the 'Dutch Aquarium' in some circles, in reference to the pioneering work carried out by European aquarists in designing these sorts of aquaria, one of the most active advocates of the heavily planted aquarium is the Japanese aquarist Takashi Amano. Marine aquarists very often attempt to recreate the coral reef in their aquaria using large quantities of living rock, porous calcareous rocks encrusted with algae, sponges, worms, and other small marine organisms. Larger corals as well as shrimps, crabs, echinoderms, and molluscs are added later on, once the aquarium has matured, as well as a variety of small fish. Such aquaria are sometimes called 'reef tanks'.

Garden ponds are in some ways similar to freshwater aquaria, but are usually much larger and exposed to the ambient climatic conditions. In the tropics, tropical fish can be kept in garden ponds, but in the cooler regions goldfish, koi, and orfe are kept instead.

The origins of fishkeeping

Fish have been raised as food in pools and ponds for thousands of years. In Medieval Europe, carp pools were a standard feature of estates and monasteries, providing an alternative to meat on feast days when meat could not be eaten for religious reasons. Similarly, throughout Asia there is a long history of stocking rice paddies with freshwater fish suitable for eating, including various types of catfish and cyprinid. Particularly brightly coloured or tame specimens of fish in these pools have sometimes been valued as pets rather than food, and some of these have given rise to completely domesticated varieties, most notably the goldfish and the koi carp, which have their origins in China and Japan respectively.

Marine fish have been similarly valued for centuries, and many wealthy Romans kept lampreys and other fish in salt water pools. Cicero reports that the advocate Quintus Hortensius wept when a favoured specimen died, while Tertullian reports that Asinius Celer paid 8000 sesterces for a particularly fine mullet.

Modern fishkeeping

Although some tropical fish were kept in gas-heated tanks in Victorian times, tropical fishkeeping only really became popular from the 1930s onwards when devices like electric heaters and cheap glass aquaria became available. Air transportation has also made it possible for fish to be imported from many parts of the world rapidly and inexpensively. As a result, aquarists are routinely offered large numbers of freshwater fish collected from South America, South East Asia, and East Africa. However, the majority of freshwater fish sold to aquarists are commercially bred, primarily in South East Asia and Florida.

Marine fish are not easily bred in captivity, and only a few species, most notably seahorses and clownfish are farm-raised. Most are collected from coral reefs, in particular from South East Asia, the Red Sea, and the Caribbean.

Aquarium hardware

See Aquarium.

Fish breeding

Fish breeding is a challenge that many aquarists find attractive. While some species reproduce freely in community tanks, most require special conditions, known as spawning triggers before they will breed. The majority of fish lay eggs, and the juvenile fish that emerge are very small and need tiny live foods or their substitutes to survive. A fair number of popular aquarium fish are livebearers, and these fish produce small number of relatively large offspring, and these will usually take ground flake food straight away (see article on livebearing aquarium fish).

Conservation and science

According to the FAO, at least 90% of aquarium fish are captive bred [1]. The rest of the fish are collected from the wild, and provide an especially valuable source of income for people in regions where other high-value exports may be lacking [2]. In theory, wild fish should be a good example of a renewable resource that places value on maintaining the integrity and diversity of the natural habitat: more and better fish can be exported from clean, pristine aquatic habitat than one that has been polluted or otherwise degraded.

However, this has not been the case with industries such as fur trapping, logging, or fishing where a similar situation existed. Historically, wild resources have tended to be overexploited rather than managed (see Tragedy of the Commons). Moreover, in places where collecting for aquaria is very intensive, there is good evidence that collecting can result in a decline in fish populations. A particular notorious example is to be found on the Philippines, where overfishing and the widespread use of cyanide to stun the fish has caused a drastic decline in the diversity of the coral reef fish considered most desirable by aquarists [3].

On the other hand, breeding programs by aquarists have helped to preserve species that have become rare or extinct in the wild, most notably among the Lake Victoria cichlids. Some species of aquarium fish have also become important as laboratory animals, with cichlids and poecilids being especially important for studies on learning, mating, and social behaviour. Aquarists also observe a large number of fishes not otherwise studied, and thereby provide valuable data on the ecology and behaviour of many species.

Animal Welfare

At its best, a properly maintained aquarium allows the fish to socialise with their own kind and in many cases breed successfully. This is in marked contrast to the conditions enjoyed by larger animals like cats and dogs, which are often kept alone and neutered, and thus unable to experience anything like a natural lifestyle. However, in many cases fish are maintained in the wrong conditions and therefore live short lives and never breed. Inexperienced aquarists often attempt to keep too many fish in their tanks, or introduce too many fish into an immature aquarium, with the result that large numbers of fish sicken and die. This has given the hobby a bad reputation among some animal welfare groups, such as PETA, for treating aquarium fish as nothing more than cheap toys that are simply replaced when they die [4].

Marine fish in particular tend to be less resilient during transportation than freshwater fish, and relatively large numbers of them die before they are finally sold to the aquarist. Although the trade in marine fish and corals for aquaria probably represents a minor threat to coral reefs when compared with habitat destruction, fishing for food, and climate change, it is a booming trade and may be a serious problem in specific locations such as the Philippines and Indonesia where most of the collecting is done [5], [6].

Goldfish and bettas in particular have often been kept in cramped bowls or aquaria that are really far too small for their needs [7]. In some cases fish have been installed in all sorts of inappropriate objects such as the AquaBabies Micro Aquaria, Bubble Gear Bubble Bag and Betta in a Vase, all of which contain live fish housed in unfiltered entirely too small quantities of water [8], [9]. These types of products are not really aimed at aquarists but rather at people looking for a novelty gift, and in fact most aquarists abhor them. Similarly, the awarding of goldfish as prizes at funfairs is traditional in many parts of the world, but has been criticised by aquarists and animal welfare charities alike as cruel and irresponsible, and giving away live-animal prizes such as goldfish was made illegal in the UK in 2004 [10].

Controversy

Modifying fish to make them more attractive as pets is an increasingly divisive issue. Historically, artificially dyeing fish was fairly common, with glassfish for example being injected with fluorescent dyes. The major British fishkeeping magazine, Practical Fishkeeping, has been effective in its campaign to remove these fish from the market by educating retailers and aquarists to the cruelty and health risks involved [11]. On the other hand, genetically modified fish like the glofish are likely to become increasingly available, particularly in the United States [12], [13].

Invasive Species

Serious problems can occur when fish originally kept in ponds or aquaria are released into the wild. While tropical species of fish will not live for long in temperate zone climates, fish released into places with similar climatic conditions to those that they originally came from can survive and potentially form viable populations. Species that have established themselves in place that they are not native to are called exotic species. Examples of exotic fish that have become established outside their normal range are the Asian snakeheads in Hawaii, African walking catfish in Florida, and goldfish in Australia. Some of these exotic species can become extremely disruptive preying on, or competing with, the native fish (see invasive species).

References and further reading

• Aquarium Atlas, vol. 1, by Hans A. Baensch and Rudiger Riehl
• Brackish Water Fishes, by Frank Schäfer
• The Conscientious Marine Aquarist, by Robert Fenner

See also

• Aquarium

See also

• Aquarium Fishdeals.com - Large web site covering all areas of fishkeeping.
• Tropical Fish Hobbyist - Popular American fishkeeping magazine.
• Wet Web Media - Large web site covering different aspects of fishkeeping.
• Aquarium Setup - Setup and maintenance guide for freshwater aquariums.
• Planet Catfish - Web site devoted to catfish in aquaria