Aquarium Fish

Angling ... In many parts of the world, size limits apply to certain species, meaning fish below and/or above a certain size must, by law, be released... Among the many species of salt water fish that are caught for sport are swordfish, marlin, tuna, salmon and halibut... In Europe a large number of anglers fish for species such as carp, pike, tench, rudd, roach, European perch and barbel (especially in stillwaters)...

Aquaculture ... The reported output from global aquaculture operations would supply one half of the fish and shellfish that is directly consumed by humans; however, there are issues about the reliability of the reported figures... Further, in current aquaculture practice, products from several pounds of wild fish are used to produce one pound of a piscivorous fish like salmon... Particular kinds of aquaculture include fish farming, shrimp farming, oyster farming, algaculture (such as seaweed farming), and the cultivation of ornamental fish...

Fish Marketing ... It can be dedicated to wholesale trade between fishermen and fish merchants, or to the sale of seafood to individual consumers, or to both...

Fish (food) ... The modern English word for fish comes from the Old English fisc (plural: fiscas) which was pronounced as it is today... There are issues with fish contaminated with heavy metals such as mercury and lead, or by toxic chemicals such as those containing chlorine or bromine, dioxins or PCBs... Mercury Fish products have been shown to contain varying amounts of heavy metals, particularly mercury and fat-soluble pollutants from water pollution...

Fish Locomotion ... Body/caudal fin propulsion There are five groups that differ in the fraction of their body that is displaced laterally : Anguilliform locomotion In some long, slender fish – eels, for example – there is little increase in the amplitude of the flexion wave as it passes along the body... Sub-carangiform locomotion Here, there is a more marked increase in wave amplitude along the body with the vast majority of the work being done by the rear half of the fish... Ocean sunfish, for example, have a completely different system, and many small fish use their pectoral fins for swimming as well as for steering and dynamic lift...

Recreational Fishing ... Other devices, commonly referred to as terminal tackle, are also used to affect or complement the presentation of the bait to the targeted fish...

Fish ... Commercial and subsistence fishers hunt fish in wild fisheries (see fishing) or farm them in ponds or in cages in the ocean (see aquaculture)... Fish have had a role in culture through the ages, serving as deities, religious symbols, and as the subjects of art, books and movies...

Disease In Ornamental Fish ... Due to their generally small size and the low cost of replacing diseased or dead fish, the cost of testing and treating diseases is often seen as more trouble than the value of the fish... Issues in diagnosis and treatment Due to the artificially limited volume of water and high concentration of fish in most aquarium tanks, communicable diseases often affect most or all fish in a tank... An improper nitrogen cycle, inappropriate aquarium plants and potentially harmful freshwater invertebrates can directly harm or add to the stresses on ornamental fish in a tank...

Fishkeeping ... In the tropics, tropical fish can be kept in garden ponds, but in the temperate zone species such as goldfish, koi, and orfe work better... Marine aquaria can be exceedingly beautiful, due to the attractive colors and shapes of the corals and the coral reef fish they host... Temperate zone marine fish are not as commonly kept in home aquaria, primarily because they do not thrive at room temperature...

Scale (anatomy) ... They come in two forms: Cycloid scales have a smooth outer edge, and are most common on fish with soft fin rays, such as salmon and carp... Ctenoid scales have a toothed outer edge, and are usually found on fish with spiny fin rays, such as bass and crappie...

Cleaner Fish ... The symbiosis does not break down because the abundance of these parasites varies significantly seasonally and spatially, and the overall benefit to the larger fish outweighs any cheating on the part of the smaller... Mimicry Many cleaner fish have a distinctive combination of a long narrow body, a longitudinal stripe, a blue colour, and small size... "Convergent signalling among cleaners, using size, stripes and colour, should facilitate their recognition by fish clients." The sabre-toothed blenny Aspidontus taeniatus is a blenny that mimics the ritualised dance the cleaner wrasse makes when passing fish swim by...

Mercury In Fish ... The presence of mercury in fish can be a health issue, particularly for women who are or may become pregnant, nursing mothers, and young children... This results in the bioaccumulation of mercury, in a buildup in the adipose tissue of successive trophic levels: zooplankton, small nekton, larger fish etc... Anything which eats these fish within the food chain also consumes the higher level of mercury the fish have accumulated...

Vision In Fishes ... The ratio of rods to cones depends on the ecology of the fish species concerned, e.g., those mainly active during the day in clear waters will have more cones than those living in low light environments...

Fish Farming ... There is an increasing demand for fish and fish protein, which has resulted in widespread overfishing in wild fisheries... However, farming carnivorous fish, such as salmon, does not always reduce pressure on wild fisheries, since carnivorous farmed fish are usually fed fishmeal and fish oil extracted from wild forage fish... The global returns for fish farming recorded by the FAO in 2008 totalled 33.8 million tonnes worth about $US 60 billion...

Animal Navigation ... William Tinsley Keeton (1933-1980) studied homing pigeons, showing that they were able to navigate using the earth's magnetic field, the sun, as well as both olfactory and visual cues. Donald Griffin (1915-2003) studied echolocation in bats, demonstrating that it was possible and that bats used this mechanism to detect and track prey, and to "see" and thus navigate through the world around them...

Live Fish Trade ... The live food fish trade is a global system that links fishing communities with markets, primarily in Hong Kong and mainland China... Consumer demand Within the live food trade there are certain types of fish demanded more often by consumers, particularly smaller and medium-sized fish... According to the book While Stocks Last: The Live Reef Food Fish Trade consumer demand has caused the fish captured on coral reefs to be the most valued fish in the trade...