Catfishes

Taxonomy:
The catfish are a monophyletic group. This is supported by molecular evidence. Catfish belong to a
superorder-Ostariophysi, which also includes the Cypriniformes, Characiformes,
Gonorynchiformes and Gymnotiformes, a superorder characterized by the Weberian apparatus.
Currently, the Siluriformes are said to be the sister group to the Gymnotiformes. There are about
36 extant catfish families, and about 3,093 extant species have been described. This makes the
catfish order the second or third most diverse vertebrate order.
Order - Siluriformes has the following families:
Extant families -
Ailiidae; Akysidae; Amblycipitidae; Amphiliidae; Anchariidae; Ariidae; Aspredinidae;
Astroblepidae; Auchenipteridae; Austroglanididae; Bagridae; Callichthyidae; Cetopsidae;
Chacidae; Clariidae; Claroteidae; Cranoglanididae; Diplomystidae; Doradidae; Erethistidae;
Heptapteridae; Heteropneustidae; Horabagridae; Ictaluridae; Kryptoglanidae; Lacantuniidae;
Loricariidae; Malapteruridae; Mochokidae; Nematogenyiidae; Pangasiidae; Pimelodidae; Plotosidae;
Pseudopimelodidae; Schilbeidae; Scoloplacidae; Siluridae; Sisoridae; Trichomycteridae;
incertae sedis - Conorhynchos
– Extinct family - Andinichthyidae
Distribution and habitat:
Living catfishes constitute nearly 2,900 species placed in about 35 families. The majority of species inhabit fresh
water, but a few, belonging to the families Ariidae and Plotosidae, are marine. Freshwater catfishes are almost
worldwide in distribution and live in a variety of habitats from slow or stagnant waters to fast mountain streams; marine
catfishes are found in the shore waters of the tropics. Catfishes are generally bottom dwellers, more active by night
than by day. Extant catfish species live inland or in coastal waters of every continent except Antarctica. Catfish have
inhabited all continents at one time or another. They are most diverse in tropical South America, Asia, and Africa, with
one family native to North America and one family in Europe. More than half of all catfish species live in the Americas.
They are the only ostariophysans that have entered freshwater habitats in Madagascar, Australia, and New Guinea.
They are found in fresh water environments, though most inhabit shallow, running water. Representatives of at least
eight families are hypogean (live underground) with three families that are also troglobitic (inhabiting caves). One such
species is Phreatobius cisternarum, known to live underground in phreatic habitats. Numerous species from the
families Ariidae and Plotosidae, and a few species from among the Aspredinidae and Bagridae, are found in salt water.
In the Southern United States, catfish species may be known by a variety of slang names, such as "mud cat", "polliwogs",
or "chuckleheads". These nicknames are not standardized, so one area may call a bullhead catfish by the nickname "
chucklehead", while in another state or region, that nickname refers to the blue catfish.
As invasive species: Representatives of the genus Ictalurus have been introduced into European waters in the hope of
obtaining a sporting and food resource. However, the European stock of American catfishes has not achieved the
dimensions of these fish in their native waters, and have only increased the ecological pressure on native European fauna.
Walking catfish have also been introduced in the freshwaters of Florida, with the voracious catfish becoming a major
alien pest there. Flathead catfish, Pylodictis olivaris, is also a North American pest on Atlantic slope drainages.
Pterygoplichthys species, released by aquarium fishkeepers, have also established feral populations in many warm waters
around the world.
Physical characteristics: External anatomy of catfish:
Most catfish are bottom feeders. In general, they are negatively buoyant, which means that they will usually sink
rather than float due to a reduced gas bladder and a heavy, bony head. Catfish have a variety of body shapes,
though most have a cylindrical body with a flattened ventrum to allow for benthic feeding.
A flattened head allows for digging through the substrate as well as perhaps serving as a hydrofoil. Some have a
mouth that can expand to a large size and contains no incisiform teeth; catfish generally feed through suction or
gulping rather than biting and cutting prey. However, some families, notably Loricariidae and Astroblepidae, have
a suckermouth that allows them to fasten themselves to objects in fast-moving water. Catfish also have
a maxilla reduced to a support for barbels; this means that they are unable to protrude their mouths as other fish
such as carp.
Catfish may have up to four pairs of barbels: nasal, maxillary (on each side of mouth), and two pairs of chin barbels,
though pairs of barbels may be absent depending on the species. Catfish barbels always come as pairs. Many larger
catfish also have chemoreceptors across their entire bodies, which means they "taste" anything they touch and "smell"
any chemicals in the water. "In catfish, gustation plays a primary role in the orientation and location of food".
Because their barbels and chemoreception are more important in detecting food, the eyes on catfish are generally
small. Like other ostariophysans, they are characterized by the presence of a Weberian apparatus.[5] Their well-
developed Weberian apparatus and reduced gas bladder allow for improved hearing as well as sound production.
Catfish do have thin scales; their bodies are often naked. In some species, the mucus-covered skin is used in cutaneous
respiration, where the fish breathes through its skin. In some catfish, the skin is covered in bony plates called scutes;
some form of body armor appears in various ways within the order. In loricarioids and in the Asian genus Sisor, the
armor is primarily made up of one or more rows of free dermal plates. Similar plates are found in large specimens
of Lithodoras. These plates may be supported by vertebral processes, as in scoloplacids and in Sisor, but the processes
never fuse to the plates or form any external armor.
By contrast, in the subfamily Doumeinae (family Amphiliidae) and in hoplomyzontines (Aspredinidae), the armor is
formed solely by expanded vertebral processes that form plates. Finally, the lateral armor of doradids, Sisor, and
hoplomyzontines consists of hypertrophied lateral line ossicles with dorsal and ventral lamina.
All catfish other than members of Malapteruridae (electric catfish), possess a strong, hollow, bony leading spine-like
ray on their dorsal and pectoral fins. As a defense, these spines may be locked into place so that they stick outwards,
which can inflict severe wounds.
In numerous catfish species, these fin rays can be used to deliver a stinging protein if the fish is irritated; as many
as half of all catfish species may be venomous in this fashion, making the Siluriformes overwhelmingly the vertebrate
order with the largest number of venomous species. This venom is produced by glandular cells in the epidermal tissue
covering the spines. In members of the family Plotosidae and of the genus Heteropneustes, this protein is so strong it
may hospitalize humans who receive a sting; in Plotosus lineatus, the stings can be lethal.
Juvenile catfish, like most fish, have relatively large heads, eyes, and posterior median fins in comparison to larger, more mature
individuals. These juveniles can be readily placed in their families, particularly those with highly derived fin or body shapes; in some
cases identification of the genus is possible. As far as known for most catfish, features that are often characteristic of species such as
mouth and fin positions, fin shapes, and barbel lengths show little difference between juveniles and adults. For many species, pigmentation
pattern is also similar in juveniles and adults. Thus, juvenile catfish generally resemble and develop smoothly into their adult form without
distinct juvenile specializations. Exceptions to this are the ariid catfish, where the young retain yolk sacs late into juvenile stages, and
many pimelodids, which may have elongated barbels and fin filaments or coloration patterns.
Sexual dimorphism is reported in about half of all families of catfish. All species are egg layers and may exhibit various types of parental
care. The brown bullhead (Ictalurus nebulosus), for example, builds and guards a nest and protects its young, while male sea
catfishes (Ariidae) carry the marble-sized eggs, and later the young, in their mouths.The modification of the anal fin into an intromittent
organ (in internal fertilizers) as well as accessory structures of the reproductive apparatus (in both internal and external fertilizers) have
been described in species belonging to 11 different families.
Catfish have one of the greatest ranges in size within a single order of bony fish. Many catfish have a maximum length of under 12 cm
(4.7 in). Some of the smallest species of Aspredinidae and Trichomycteridae reach sexual maturity at only 1 centimetre (0.39 in).
The wels catfish, Silurus glanis, and the much smaller related Aristotle's catfish are the only catfish indigenous to Europe: the former
ranging throughout Europe, and the latter restricted to Greece. Mythology and literature record wels catfish of astounding proportions, yet
to be proven scientifically. The average size of the species is about 1.2–1.6 m (3.9–5.2 ft), and fish more than 2 metres (6.6 ft) are rare.
However, they are known to exceed 2.5 metres (8.2 ft) in length and 100 kilograms (220 lb) in weight. In July 2009, a catfish weighing
88 kilograms (194 lb) was caught in the River Ebro, Spain, by an 11-year-old British schoolgirl.
In North America the largest Ictalurus furcatus (Blue catfish) caught in the Missouri River on 20 July 2010, weighed 59 kilograms
(130 lb). The largest flathead catfish, Pylodictis olivaris, ever caught was in Independence, Kansas, weighing 56 kilograms (123 lb).
These records pale in comparison to a giant Mekong catfish caught in northern Thailand on 1 May 2005 and reported to the
press almost 2 months later that weighed 293 kilograms (646 lb). This is the largest giant Mekong catfish caught since Thai
officials started keeping records in 1981. Also in Asia, Jeremy Wade caught a 75.5 kilograms (166.4 lb) Goonch following three
fatal attacks on humans in the Kali River on the India-Nepal border. Wade was of the opinion that the offending fish must have
been significantly larger than this to have taken an 18-year-old boy as well as a water buffalo.
Piraíba (Brachyplatystoma filamentosum) can grow exceptionally large and are native to the Amazon basin. They can occasionally
grow to 200 kg (440 lbs), as evidenced by numerous catches. There are also reports in the region of deaths from being
swallowed by these fish.
Sound production and interpretation:
Catfish can produce different types of sounds and also have well-developed auditory reception used to discriminate between
sounds with different pitches and velocities. They are also able to determine the distance of the sound's origin and from what
direction it originated. This is a very important fish communication mechanism, especially during agonistic and distress behaviors.
Catfish are able to produce a variety of sounds for communication that can be classified into two groups: drumming sounds
and stridulation sounds. The variability in catfish sound signals differs due to a few factors: the mechanism by which the sound is
produced, the function of the resulting sound, and physiological differences such as size, sex, and age. To create a drumming
sound, catfish use an indirect vibration mechanism using a swimbladder. In these fishes, sonic muscles insert on the ramus Mulleri,
also known as the elastic spring. The sonic muscles pull the elastic spring forward and extend the swimbladder. When the muscles
relax, the tension in the spring quickly returns the swimbladder to its original position, which produces the sound.
Catfish also have a sound-generating mechanism in their pectoral fins. Many species in the catfish family possess an enhanced
first pectoral fin ray, called the spine, which can be moved by large abductor and adductor muscles. The base of the catfishes'
spines has a sequence of ridges, and the spine normally slides within a groove on the fish's pelvic girdle during routine movement;
but, pressing the ridges on the spine against the pelvic girdle groove creates a series of short pulses. The movement is analogous
to a finger moving down the teeth of a comb, and consequently a series of sharp taps is produced.
Sound-generating mechanisms are often different between genders. In some catfish, pectoral fins are longer in males than in
females of similar length, and differences in the characteristic of the sounds produced were also observed. Comparison between
families of the same order of catfish demonstrated family and species-specific patterns of vocalization, according to a study by
Maria Clara Amorim. During courtship behavior in three species of Corydoras catfish, all males actively produced stridulation
sounds before egg fertilization, and the species' songs were different in pulse number and sound duration.
Sound production in catfish may also be correlated with fighting and alarm calls. According to a study by Kaatz, sounds for
disturbance (e.g. alarm) and agonistic behavior were not significantly different, which suggests distress sounds can be used to
sample variation in agonistic sound production. However, in a comparison of a few different species of tropical catfish, some fish
put under distress conditions produced a higher intensity of stridulatory sounds than drumming sounds. Differences in the
proportion of drumming versus stridulation sounds depend on morphological constraints, such as different sizes of drumming muscles
and pectoral spines. Due to these constraints, some fish may not even be able to produce a specific sound. In several different
species of catfish, aggressive sound production occurs during cover site defense or during threats from other fish. More
specifically, in long-whiskered catfish, drumming sounds are used as a threatening signal and stridulations are used as a defense
signal. Kaatz investigated 83 species from 14 families of catfish, and determined that catfish produce more stridulatory sounds
in disturbance situations and more swimbladder sounds in intraspecific conflicts.
Economic importance: Aquaculture:
Catfish are easy to farm in warm climates, leading to inexpensive and safe food at local grocers. About 60% of U.S. farm-raised
catfish are grown within a 65-mile (100-km) radius of Belzoni, Mississippi. Channel catfish (Ictalurus punctatus) supports a $450
million/yr aquaculture industry. The largest producers are located in the Southern United States, including Mississippi, Alabama,
and Arkansas.
Catfish raised in inland tanks or channels are usually considered safe for the environment, since their waste and disease should
be contained and not spread to the wild.
In Asia, many catfish species are important as food. Several airbreathing catfish (Clariidae) and shark catfish (Pangasiidae)
species are heavily cultured in Africa and Asia. Exports of one particular shark catfish species from Vietnam, Pangasius bocourti,
have met with pressures from the U.S. catfish industry. In 2003, The United States Congress passed a law preventing the
imported fish from being labeled as catfish. As a result, the Vietnamese exporters of this fish now label their products sold in
the U.S. as "basa fish." Trader Joe's has labeled frozen fillets of Vietnamese Pangasius hypophthalmus as "striper."
There is a large and growing ornamental fish trade, with hundreds of species of catfish, such as Corydoras and armored
suckermouth catfish (often called plecos), being a popular component of many aquaria. Other catfish commonly found in the
aquarium trade are banjo catfish, talking catfish, and long-whiskered catfish
Catfish as food:
Catfish have widely been caught and farmed for food for hundreds of years in Africa, Asia, Europe, and North America.
Judgments as to the quality and flavor vary, with some food critics considering catfish excellent to eat, while others dismiss
them as watery and lacking in flavor. Catfish is high in vitamin D. Farm-raised catfish contains low levels of omega-3 fatty
acids and a much higher proportion of omega-6 fatty acids.
In Central Europe, catfish were often viewed as a delicacy to be enjoyed on feast days and holidays. Migrants from Europe and
Africa to the United States brought along this tradition, and in the Southern United States, catfish is an extremely popular food.
The most commonly eaten species in the United States are the channel catfish and the blue catfish, both of which are common in
the wild and increasingly widely farmed. Farm-raised catfish became such a staple of the U.S. diet that President Ronald
Reagan established National Catfish Day on 25 June 1987 to recognize "the value of farm-raised catfish." Catfish is eaten in a
variety of ways. In Europe it is often cooked in similar ways to carp, but in the United States it is popularly crumbed
with cornmeal and fried.
In Indonesia, catfish is usually served fried or grilled in street stalls called warung and eaten with vegetables, sambal, and
usually nasi uduk, the dish is called pecel lele or pecak lele. The same dish can also be called as lele penyet (squashed catfish)
if the fish is lightly squashed along with sambal in the stone mortar. The pecel/pecak version present the fish in separate plate
while the stone mortar is solely for sambal (Lele is the Indonesian word for catfish.)
In Malaysia catfish, called ikan keli, is fried with spices or grilled and eaten with tamarind and Thai chillies gravy and also is
often eaten with steamed rice.
In Bangladesh and the Indian states of Odisha, West Bengal and Assam, catfish (locally known as magur) is eaten as a favored
delicacy during the monsoons. In the Indian state of Kerala, the local catfish, known as thedu' or etta in Malayalam, is also
popular.
In Hungary catfish is often cooked in paprika sauce (Harcsapaprikás) typical of Hungarian cuisine. It is traditionally served with
pasta smothered with curd cheese (túrós csusza).
In Myanmar (formally Burma), catfish is usually used in mohinga, a traditional noodle fish soup cooked with lemon grass, ginger,
garlic, pepper, banana stem, onions, and other local ingredients.
Vietnamese catfish (Pangasius) cannot be legally marketed as catfish in the United States, and so is referred to as swai or basa.
Only fish of the family Ictaluridae may be marketed as catfish in the United States. In the UK, Vietnamese catfish is
sometimes sold as "Vietnamese river cobbler", although more commonly as Basa.
In Nigeria, catfish is often cooked in a variety of stews. It is particularly cooked in a delicacy popularly known as "catfish pepper
soup" which is enjoyed throughout the nation.
Fish must have fins and scales to be kosher. Since catfish lacks scales, they are not kosher.
Dangers to humans:
While the vast majority of catfish are harmless to humans, a few species are known to present some risk. Many catfish species
have "stings" (actually non-venomous in most cases) embedded behind their fins; thus precautions must be taken when handling them.
Stings by striped eel catfish have killed people in rare cases.