LITERATURE REVIEW

Introduction to Catf'ish

Catfish have unique structural and functional differences and adaptations that

help them survive even in highly adverse environmental conditions. Families such as

Clariidae and Heteropnercstidae have air-breathing organs arising from the bronchial

arches. They can withstand water of poor quality and can respire in air. Hence they

are able to survive for hours or even for a few days in land (Day 1989, Jayaram

1999).

They do not have scales except the armored forms (e.g. - Doradids,

Loricariids), which are covered by skin with hard plates (Goulding 1980, Sabaj et a / .

1999). Most of the genera contain adipose dorsal fin that lies between the dorsal and

caudal fins. The first pectoral and last dorsal fin rays are modified as hard pungent

spines or thick rays, which may or may not be pisonous. These spines are used as

organs of defense. They have harbels in their maxilla and mandible usually one to

four pairs that are used as sensory organs. Many species are detritivorous bottom

feeders and are provided with pharyngeal. pterygoid, palatine and vomerine teeth in

their gill arch and mouth (Jayaram 1999).

The species. Hora~lanis krishnai in Kerala, which belongs to the family

Clariidae, is small, subterranean and hlind. The other hlind catfish species across the

world are, Clarias mvernic.ola of South West Africa Clariallabes of Lower Congo,

G.~na l lahes of Lower Niger and Old Calahar, Channallabes of Congo and Angola.

Dolich//ahps of Kunungu, B. Congo and Ve~itglanis of Italian Somaliland (Menon

1950). Some fishes (E.g. - Parasilurrts asot~rs) have electro reception capacity, thus

can ncognize earthquakes in advance (Munshi 2003). The males of Ariid species and

few other marine forms carry the eggs inside their mouth until they hatch out (Day

1989). Tht bagrid catfish Aorichrhys m r and the loricariid fish Ancisrrus sp. exhibit

can and build nest for their young ones (Jayaram 1999).

The giant catfish, Pangasinnrdon ~ i ~ r r s is distributed in the Mekong River of

South East Asia including Cambodia, Tha~land, Laos and Vietnam. The Guinness

Book of World Records lists this as the earth's largest freshwater fish. It grows up to

3m in length and 300 kg in weight (Hogan et (11. 2004). In India, the size varies from

5 cm to 3 m (Talwar and J h inpn 199 1 ).

Fishes of the genera. Clarias and Heteropneusres are highly nutritive. The air

bladders of some marine catfish are exported to Chna for their valuable Isinglass

(Day 1989).

2.1 TAXONOMY

There iire ahout 30 families of catfisheh distributed in the world and two of

them including Ar i ihe and Plornsidue iire secondarily marine. Ariidue is distributed

in dl tropical region5 including Australia, and Plotosidur is distributed in countries

located near the Indo-Pacific. There are 14 endemic families of purely freshwater

catfishes seen in South America. eight In Asia and three in Africa. The families such

as Ba,qridae, Schilhidue and Cluriidue are found in Asia and Africa. (McConnell

1987).

In his study on the classification of the Oriental and Palaearctic family

Siluridue. Haig (1950) has listed about 53 species belonging to 9 genera. When

quoting the history of the catfish families. he says 'The catfishes as a whole

(Nemu~ognuthi or Siluroidea) have been recognized as a natural group since early

times. For many years all of them with the exception of the armoured foms, were

p h e d in the family Siluridae, named after the type genus Silurccs". Bleeker. Gunther

and others variously subdivided these catfishes. Regan (191 1 ) was the first to

separate the Old World catfish groups on the basis of thorough osteoiogicd study.

* monomic studies on the hdian fish fauna were done in the 19" century

(Hamilton-Buchanan 1822. McClelland 1839, Sykes 1839, Jerdon 1849, Day 1875-

1878. Gunther 1859-70). the 2ofh century. Hora (1920-52). Mukerji (1936). Misra

(1947. 1952, 1953. 1962). Tilak (1987). Menon (1987, 1992). Talwar and Jhingran

(1991) conducted taxonomic stud~es. Among these, extensrve fish surveys were by

Hora (19361, Misra (1947-19621, Day (1986). Talwar and Jhlngran (1991), Jayaram

(1976, 1978, 1999) and Menon (1999)

In India, the inltral Catfish descriptions were made m the 19" century by

lchthyolopists such a\ Hamilton-Buchanan (1822) and Jerdon (1849). In the 20"

century catfish specier were described by Datta et al. (1987). Remadevi and

Raghunathan (19991, and Vishwanath and Kosygin (1999).

Major reviews on the Indian Catfish fauna were camed out by Day (1889).

Hora ( 1936,19491, J a y m ( 1966. 1972. 198 1.1982) and Misra ( 1976). Some of the

other reviews include Chaudhun ( 1912. 191 3), Rosrell ( 1964). Rohens ( 1982).

Virwanath and Sinph ( 1986). Munshr and Snvastava ( 1988). and Talwar (1971 ).

The systematics and geograph~cal distnhution of the Asian Sllund Catfish of

the genus, Wullugo was done by Robens (1982). In 1992, he has reviewed the ctnped

catfishes of Thailand. The systematics of some catfish genera such as Akvas. Olvra,

Wullugo, He~eropneustes. Clur[us. Sllunrs, Call~c~hrous. Erethlstes, Erethrstoldes.

Conru and Ham was reviewed hy Hora ( 1936. 1949) Jayaram ( 1976) expluned the

1ntemlationsh1p of the Indo-Afncan Bagnd catfishes. The mmne catfish family

Auldue w a reviewed based on the structure\ and body parts of the fishes by Jayarm

and Dhanze (1978). Few other taxonomrc studies on the Indran Catfish have been

conducted by Motwanr and Saipal(1974). Daniels (2000.2002). Jayaram and Sanyal

(2003).

Recently, m y lchthyolopists have listed the status of Indian Catfish species.

Day (1986) recorded about 1 16 species of catfishes representing 30 genera under the

family Siluridoe and order Physostomi. Talwar and Jhingran (1991 ) reported 158

species of catfishes from 50 genera and 13 families. In his study, Jayaram (1999)

listed about 158 species from 51 genera belonging to 13 families. He has further

classified the genus Rama into Chandramara. Menon (1999) recorded about 74

species of purely freshwater catfishes from 37 genera belonging to 10 families. But

he has left out the marine / estuarine-visiting catfishes of the families Ariidae and

Plorosrdae.

The recent surveys and new records have been carried out from various states

of India. However, most of them were concentrated on Kerala and Northeastern

states. Fish surveys in Kerala State include, Menon (1950). Zacharias er a / . (1995,

Easa and Shaji (1997). Kumar el a / . (1999) Biju et a/. (19991, and Thomas et of .

(2002). Catfish surveys of the Northeastern states are, Barman (1994). Keishing and

Vishwanath (1999), Selim and Vishwanath (1999). and Vishwanath and Kosygin

(1999).

2.2 DISTRIBUTION

Although, there were many studies conducted on the systematics, feeding,

breeding ecology and morphometrics of catfishes in India, studies on their

distribution including species richness, abundance and composition are limited,

(Kumar and Mittal 1993; Kumar el (11.1995; Kumar et a/. 1999). Some of the catfish

surveys and records fmm a few states include Tilak (1969) in Uttar Pradesh,

Ramakrishniah ( 1986) in Andhra Pradesh and Kumar el 01. (1995) in Rajasthan. Fish

surveys have been conducted from different parts of Tamil Nadu (Raj 1916,

Venkateswarlu et al. 1975. Singh 1976, Raghunathan 1978, lndra 1992. and

Remadevi cr al. 1999).

The habitat preference and distribution of air breathing fishes including

Heteropncllstes fossilis and Clarias barraducs were studied among the wetlands of

Keoladeo National Park, Rajasthan by Kumar and Mitutl (1993). Kumar et al. (1995)

studied the composition, abundance and distribution of a few species of catfish from

Banganga Gambhir River system. in 1999, they studied the cat fish fauna, their

abundance and distribution along with the other fish species in Chalakudy river

system, Kerala and reported Ompok malaharicus for the first time from the river and

also found the second most abundant genus was Mystus.

In India, catfish diversity is high in the Northeaqt followed by the Western

Ghats and its neighboring States. The highest number (33) of species was recorded

from the rivers of Tripura (Barman 1994) and (17) species have been recorded from

Southern Kerala (Thomas et al. 2002).

In and around Kancheepuram, many studies have recorded catfishes. Raj

(1916) recorded 8 species, and more recently Venkateswarlu et al. (1975) recorded

18 from 6 families. Chembararnpakkam Lake is an important water body for

catfishes in Kancheepuram district. Remadevi et al. (1999) listed 6 species from 3

families. Daniels and Rajagopal (2004) recorded 4 species from 2 families.

The catfish records from Kanyakurnari region include that of Singh (1976).

who listed 1 I species of catfish. of which 4 were marine and 7 were freshwater. lndra

(1992) recorded 5 species of catfishes from the same district. Four species belonging

to the genus Mvstur and one belonging to the genus Heteropneustes of the families

Bagridae and Heteropneustidae respectively.

2.3 FOOD AND FEEDING ECOLOGY

The feeding ecology of catfish has been studied in different parts of the world

(Saul 1975, Gouldine 1980, Baras and Laleye 2003. Trajano 2003). Study done by

Saul (1975) in the Upper Amazonian Ecuador shows that many species of catfishes

eat a large quantity of insects, mostly ants. The Aspredinid catfishes eat insect

debris, plant debris and fly larvae, Callichthvid catfishes eat sand, and plant debris,

diatom., insect debris, fly larvae and Chironomids. The Loricariid catfishes eat sand

and detritus.

Few other catfishes in Amazon are generalist feeders, feeding on fruits,

seeds, insects, crustaceans, mollusks, fish and plankton. Fishes of the family

Pimlodrdae prefers fish, crabs, fruits, seeds and some vegetative matter. The fishes

of the family Doradidae eat fruits, vegetation, snails, zooplanktons and crustaceans

(shrimps) and Auchenipferid fishes eat fruits, beetles, termite nest and invertebrates.

(Goulding 1980).

Loricariid fish feed on wood, Pimelodids on fish and the Trichomycterid

species swive as parasites on the other larger fish (Baras and Laleye 2003). Food

preferences of different species from these regions show that most of the catfish

species are generally omnivores with inclination towards insectivorous and

detntivorous feeding habits.

The subterranean catfishes are mostly omnivorous. generalist carnivores

feeding on crustaceans such as copepods and crayfish, aquatic insects, mollusks

mainly gastropods, annelid. nematode worms, arachnids and terrestrial insects

(Trajano 2003 1.

The feeding ecology of catfish in lndia has been widely studied. (Rajan 1963.

1965. Bhatt 197 1, Ramakrishnaiah 1983, Piska et al. 1989 & 90. Devi el al. 1992,

and Yusuf and Majumdar 1993). The food and feeding studies on a few species of

catfish from Chilka Lake show the fish Tachysurus orius of the family Ariidae is

omnivorous and a detritus feeder, Tach~surus fnlcarius is piscivorous, Tachysurus

satporanus and Mvsrus rava,~ius are detritus feeders, and Mystus gulio is omnivorous

(Rajan 1965).

Feeding studies in lndirt have been conducted mostly on Bagrid catfishes.

(Bhatt 1971) studied specimens of Mystus virtatus collected from the Aligarh fish

w e t and observed insect larvae, copepods. daphnids, rotifers etc in their put, food

intake was lower during summer months before spawning. Individuals of Mystus

"inatus from lower Manair reservoir, Karim Nagar was an omnivorous column

feeder with a tendency towards carnivorous feeding habit. The food items were

mainly insects and their larvae and included crustaceans, rotifers, bryozoans,

oligochaetes, algae and plant material (Plska er 01. 1989 & 90). Study on the feeding

habit of B a p d catfish, Rita rita. from Yamuna river shows that it is a bottom feeder.

feeding on insects, crustiiceans, shrimps, ga..tropods, and lamellibranchiates (Devi et

ul. 1992). The morphology of the alimentary canal and food habits of Mvstus gulw

from saline sewage-fed wetlands at Minakhan shows the fish tends to be carnivorous.

Its diet includes crustaceans, small fish and plankton (Yusuf and Majumdar 1993).

The study on the biology of Pseudeutrnpius taakree. a Schilbeid catfish from

Nagarjunasagar reservoir shows the fish is carnivore. Their diet includes insects,

fishes, mollusks and crustaceans (Ramakrishnaiah 1983).

A few studies in the laboratory have been conducted in India (Sahoo er a/.

2002, Srinivsasachar et a / . 1976. and Nayak er a/. 2003). Few of these are on the

catfishes of Tamil Nadu. Some of them are by Kaliamurthy and Rao (1970).

Santhanakumar and Job (1983). Sampath and Muthukrishnan (1985). Raj ( 2 0 0 2 ) and

Raghunathan et ul. ( 2 0 0 3 ).

The freshwater catfishes of different families vary in their feeding habits. The

fishes of the family Sisoridae are omnivorous and bottom feeders, eating debris,

insect larvae. worms, plankton and plant material. The Bugrid fishes which are

carnivorous, feeding on endogenous arthropods including aquatic insects, prawns,

small fish and detritus. They dso eat fish, decapods and crustacea. Silurids are

carnivorous eating endogenous arthropods such as aquatic insects, prawns, small

fish, detritus, and large predators such as fish, decapods and crustacea. Clariid fishes

are dso c ~ i v o r o u s , fetdinp on fish, decapods and crustacea. The fishes of the

families Schi/beidae, Pangassidae and Heteropneusridae are carnivorous eating

endogenous arthropods including aquatic insects, prawns, small fish and detritus aS

the Silurgs do (Raghunathan et a1 2003).

Feeding study on a few catfish species from the Puiicat Lake shows the fish

Plotosus canius. My.~tus ~ u l i o and Tuchysurus nenga an: benthic feeders eating

amphiopods, polychaetes, mollusks and others (Kaliamunhy and Rao 1970). The

feeding biology of Mystus kelerius from Tambaraparani River shows the fish mainly

consumes organic debris and feeds throughout the year including breeding season

(Santhanakumar and Job 1983). Another study of Mystus montunus from

Tarnbarabarani river in Timnelveli reveals the fish as omnivorous that feeds on

algae, copepods, rotifers. insect larvae, cladocerans, crustaceans, mollusks, annelid

worms, small fish, fish scale, detritus and some unknown items (Raj 2002).

2.4 BREEDING ECOLOGY

Various authors have studied the breeding ecology of catfish both in the wild

and in aquaria. (Mollah 1988. Sabaj et al. 1999. Maehata 2001. 2002. Baras and

Laleye 2003, Power 2003 and Trajano 2003).

Studies on the influence of environmental factors on the spawning of Silurus

hin~uensis. in Lake Biwa, Japan show the changes in water level and temperature

critically affects its spawning.

Maehata (2002) observed the reproductive ecology of Silurus lirhophilus and

confirmed the spawning occurred at midnight at shallow roiky places on the shoal

from early May to mid-July, earlier than that of Silurrts hiwaensis in low water

temperature wd in low densities. Ln the same year he studied the mating behaviour of

Silurus asotus from M e Biwa and found the species has similar kind of mating

behaviour as that of Silurus hiw~aensis and Silrrrus lirhopltilus but different from

those of the Ooi river system in Kyoto Prefecture.

The seasonal reproduction is most common in subterranean catfishes.

Vegitglanis mmmorunoi reproduces during the dry, hot season (January to March).

Few catfish from Brazil reproduce at the end of the rainy season (March). Some fish

lay large number of eggs (Ancistrus cryptophthalmus and Rhamdiu sp.) and some lay

small number of eggs (Horagliznis krishnai) to withstand the unfavorable conditions,

conditions are favorable only for a limited period (Ercolini et a/. 1982, Mercy er

al. 1982, Weber 1996. Trajano 2003).

In India, a few studies have been conducted on the breeding of catfish. (Bhan

197 1. Saxena 1972. Thakur 1978, Ramakrishnaiah 1983, Roy and Pal 1986, Raj

2002). Seasonal changes in the gonad maturity of Myvtus tittatus reveals the fish

spawns only once during the breeding season (August to September, Bhatt 1971).

The maturity and fecundity of Rita rita of Ganga River system was studied by

Saxena (1972). He concluded that the spawning takes place more than once in a

season with a peak in July and August. (Thakur 1978) experimented with the

maturity and spawning of Clarias harraclrus collected from the wild and found that

the species has a very shon spawning period during the months of July- August. It

spawns only once during a year probahly only once during a breeding season and the

fish matures at the end of the first year of its life.

The study on breeding hehaviour of Pseuderctrc~pius tuakree in

Nagarjunasagar reservoir. Andhra Pradesh shows the fish breeds in the river, whch

is located above the reservoir during June-September (Ramakrishnaiah 1983).

Karamchandani and Motwani (1955). Saxena (1972) have stated that the

collection of larvae and juveniles of Riru ritu from River Ganga during July and

Au@s~ months shows that the breeding season for this species might be from March

to August.

The spawning season is not so distinct for Dormitator larjfrons in the Chone

River Basin, Ecuador w d the presence of juveniles in the dry season indicates that its

reproduction occurs throughout the year (Chang and Navas 1984).

Sin@ and Agarwd (1986) have quoted that the rains and floods will change

the w a t a quality and this c h ~ g e may stimulate the fish for Imturation.

Comparisons on the population size structure and gonad condition of seven

common Serranochromis species during two different semns (falling water - May

to August and low water - September to December) in the Upper Zambezi River

floodplain indicates that these species initiates spawning near the end of the low

water period (Winemiller 1991 ).

2.5 OTHER STUDIES OF RELEVANCE

The relative abundance. sex ratio and population structure of the Japanese

Eel. An~ui l l a jupotticu wa9 studied in the Tanshui river system in Northern Taiwan

(Tzeng et ul. 1995).

Few studies were done on the influence of environmental factors on the fish

fauna (species richness) in 1980s (Boyle 1980, Bregazzi and Kennedy 1982. Nelson

1982. Joshi and Bhatt 1986. Angermeier and Schlosser 1989 and Hugueny 1989).

Recently similar types of studies have heen conducted (Gonzalez and Dunson 1991,

Lorenz and Taylor 1992, Matthews er 111. 1992. Das er (11. 1995. Amarasinghe and

Welcomme 2002 and Prasad 2002).

Morphometric studies have heen carried out on different fish species in India

and other countries (Rao and Rao 1972. Natarajan et ul. 1977. Chang and Navas

1984, Winemiller 1991. Tzeng er ~1.1995, komi and Okosuwei 1999).

The ecological studies conducted on the other fishes in India include,

spawning ecology of Schis)thorar plagiostomus hy Singh and Agarwal (1986) and

the breeding biology of Pwtti~~s,fi /an~mto.~u.r hy Vijaydumar (1986).

2.6 CONSERVATlON AND MANAGEMENT

Various authors have discussed the conservation of fish (Edwards e t a / . 2002.

Baras 2003. Fu el 01.2003, Raj 2002 and Hogan ct al. 2004).

In China, conservation of endangered and economic fishes has been

prioritized. The commercial fishing of endangered fish is banned. Chinese Sturgeon.

an e n d w e d f ~ h species is conserved by producing their young ones by mificial

propagation and restocking into rivers. The fishermen are also involved in protecting

the sturgeons; they release the incidental caches back into the river (Wei et aI.

1997). The other conservation measures include, restocking the economically

important species, establishing fishery sanctuaries, ordering closed seasons and

combining fisheries with aquaculture (Zhu et al. 1997 and Li 1999). According to Fu

ef a/ . (2003). environmental policies should include information on the role of

species diversity in the functioning of ecosystems. A database on inland water

organisms and information about their environment should be established and also

\haring the idea\ and collaboration between institutions and governmental agencies

are needed for the effective conservation of fishes.

Hogan er dl. (2004) has suggested a few tactics for the conservation of

Mekong's critically endangered giant catfish Pongasia~~odon gigas. They include,

purchasing the right to catch fish in a particular area and not implementing that.

Purchasing the fish from the fishermen in it5 live condition and release them back

into the river. He also says that catching the fish for artificial breeding should be

banned, instead the government fisheries department should breed the fish and

supply the fingerlings for aquaculture sector.

Edwards et a / . (2003) discussed about consenation of the fish fauna of

Chihuithuan Descrt ecosystem. According to him. a few remaining valuable faunas

of this region and their unmodified ecosystems need careful management for their

active conservation and the information on aquatic communities can also be used for

the management of this ecosystem.

Conservation of endangered fishes cannot he possible without protecting the

rcsoumes, which support the diversity and abundance. Non-sustainable managmen[

of the peninsular water resources threatens the survival and existence of mmY

commercially important native species of fishes (Chakrabmy 1996).

In India, a few of the rare species are protected and there are no reserves that

have been established for native fish conservation. Some of the conservation

measures for the endangered catfish'My~tus wtontanus, include, in situ conservation

(establishment of fish sanctuaries 1 marine parks). habitat restoration, stock transfer,

(obtaining sufficient number of fertilized eggs and the hatched larvae are introduced

into a new environment), ex situ conservation (cryopreservation of sperms, eggs or

embryos and storage of cell cultures represent alternative methods of maintaining

genetic variants) and captive breeding (Raj 2002).