GENERAL INTRODUCTION

ornamental fish keeping is one of the most popular hobbies in the world.

The growing interest in aquarium fishes has resulted in a steady increase in the aquarium

fish trade globally. The aquarium fish trade with a turn over of US $5 billion and an

annual growth rate of 8 % offers a lot of scope for development. The top exporting

country is Singapore followed by Hong Kong, Malaysia, Thailand, Philippines, Srilanka,

Taiwan, Indonesia and India. The largest market of ornamental fish is USA followed by

Europe and Japan. Over US $ 500 million worth of ornamental fishes are imported into

USA every year.

Ornamental fishery

The ornamental fish sector is an extensive component of international trade,

fisheries, aquaculture and development. Global statistics reported to FAO from Member

States indicate that the world export value of ornamental fish in1998 was US $174

million, with imports valued at US $257 million. Developing countries account for 63

percentage of the export potential (www.fao.org/news/ 1999/990901 -e.htm).

India's share of the ornamental fish trade is estimated to be Rs.158.23lakhs which

is only 0.008 percentage of the global trade. The major part of the export trade is based on

wild collection. There is very good domestic market too, which is mainly based on locally

bred unusual species. The overall domestic trade of ornamental fish has crossed the Rs. 10

crore mark and is growing at the rate of 20 percent annually. The earning potential of this

sector has hardly been understood and the same has not being exploited using modern

technology.

Presently, Indian export almost entirely depends on freshwater species of

ornamental fishes, the major exporting centres being Kolkata, Chennai and Mumbai.

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About 90% of Indian exports go from Kolkata followed by 8% from Mumbai and 2%

from Chennai (Ghosh et al., 2000). USA, Europe and Japan are the largest markets for

ornamental fish but more than 65% of the exports come from Asia. Although India is still

in a marginal position, its trade is developing rapidly. An estimate carried by MPEDA

shows that there are one million fish hobbyists in India. The internal trade is estimated to

be about US $3.26 million and the export trade is in the vicinity of US $0.38 million. The

annual growth rate of this trade is 14% (Ghosh et al., 2000). Potentially, the inland fish

resources of India are the richest in the world.

About 80% of Indian market for ornamental fishes is of freshwater origin and the

rest are marine and brackish water fishes and invertebrates. Export from Asian countries

accounts for nearly 60% of the total export trade in ornamental fishes (Thakur, 1997).

Ninety five percent of our ornamental fish export is based on wild collection. A major

portion of the indigenous ornamental fish trade in India is from the North Eastern states

and the rest is from Southern states, which are the hot spots of fish biodiversity in India.

This capture based export is not sustainable and it is a matter of concern for the industry.

In order to sustain growth, it is absolutely necessary to shift the focus from capture to

culture based development since most of the fish species grown for their ornamental

importance can be bred in India successfully. Organized trade in ornamental fish depends

on assured and adequate supply of demand, Which is possible only by mass breeding.

Young ones were fed mainly with Infusoria, Artemia, Daphnia, Mosquito larvae, Tubifex

and Chironomus in captivity. For rearing formulated feeds were used. At present, no

indigenous prepared feed for aquarium fish is available. Ornamental fishery resources

face a range of challenges: the need for their conversion and sustainable use; the need to

ensure that benefits are equitably shared; problems caused by habitat loss and

degradation, harmful fishing practices (over-fishing and destructive fishing, such as by

xlv

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the use of cyanide); and changes in international trade patterns and concerns about the

introduction of exotic species.

Ornamental fishes are called 'live jewels' for their beautiful colours and playful

behaviour (Thakur, 1997). Ornamental fish keeping and its propagation has been an

interesting activity for many, which provided not only aesthetic pleasure but also

financial openings. About 600 ornamental fish species have been reported worldwide

from various aquatic environments. Indian waters possess a rich diversity of ornamental

fish, with over 100 indigenous varieties, in addition to a similar number of unusual

species that are bred in captivity. Among the indigenous species and exotic freshwater

species, the varieties having a good demand can be bred and reared for commercial

purpose. Species that can be produced easily and popular commercial varieties come

under egg layers and live bearers. Among the livebearer species, guppies (Poecilia

reticulata) are the simplest to start with since they can tolerate great variations in water

quality and accept all types of foods. The other popular live bearers are molly (Mollinesia

sp.), sword tail (Xiphophorus sp.) and small species like platy.

The most important group of the egg layers comes under the family Cyprinidae,

which include carps, barbs, rasboras, danios, tetras, catfishes, etc,. Goldfish (Carassius

auratus) has been very famous aquarium fish for decades throughout the world. Koi carp

(Cyprinus carpio var koi) has been getting importance for aquariums and garden pools, in

recent years with different colour combinations. India is a land of barbs and many

varieties of barbs are being bred here. Indigenous danios like zebra danio (Brachydanio

rerio), tetras like window tetra (Cymnocrocynbus sp.), neon tetra (Hyphessobrycon

innesi), serpae tetra (Hyphessobrycon callistus) etc are available. A group of fish referred

to as bubble-nest builders are a novelty to aquariums with their wonderful colours. They

xv

are air-breathers. Cichlids such as angelfish (Pterophyllum scalare) are another major

group of aquarium breeding fishes. Some indigenous fishes like red-line torpedo fish

(Pun tius densoni), loaches (Botia sp.), leaf-fish like Nandus nandus, snakehead (Channa

orientalis) and a few ornamental catfish have a good demand in foreign markets and can

be tried for breeding and propagation (www.ornamentalfish.org/) . The egg layers lay

sticky (Aploch el/us lineatus) or non sticky eggs on the glass wall or aquarium plants.

Some parents show parental care and some destroy their eggs and so different breeding

environments are needed. Live bearers release the young in batches and so they are easy

to breed.

Among the preferred fish, there are common exotic live bearers like guppy,

Poecilia reticulate; molly, Poecilia latipinna; sword tail, Xiphophorus he/len; platy,

Xiphophorus maculatus and egg layers like goldfish, Carrassius auratus; koi, Cyprinus

carplo; tiger barb, Puntius tetrazona; Siamese fighter, Betta splendens; serpae tetra,

Hyphessobrycon serpae; and some imported fish like silver shark, Ba/atocheilus

melanopterus; angel, Pterophyllum sca/are; red-tailed black shark, Labeo bicolor; red-

finned shark, Labeo erythurus. Sometimes the aquaculturists are collecting the fry of

native ornamental fish and selling them after rearing and domesticating them. The native

ornamental fish include honey gourami, Co/isa chuna; killifish Aplocheilus lineatus

(Menon, 2000); rosy barb, Puntius conchonius; zebra fish, Brachydanio renio; glass fish,

Chanda nama; reticulate bach, Botia lohachata. Presently only about 52 native fish

species from West Bengal have been earmarked as aquarium fish (Ghosh et al., 2003).

India has some of the finest ornamental fishes in the seas around Lakshadweep

and Andaman and Nicobar Islands besides Kerala, the Gulf of Mannar, Palk Bay and

xv'

Gujarat. Notable among these are a number of species of damsel fishes, parrot fishes,

surgeon fishes, wrasses and butterfly fishes.

Killifish fishery

Killifish (Cyprinodontidae-toothed carps) are a very diverse, gorgeously

multicoloured, interesting group of freshwater minnows found all over the world and

mainly in equatorial regions. Killifish are fairly widespread throughout Africa, Asia,

South America, North America and parts of Europe. These fishes are almost present in

every biotope in freshwater. Several species also inhabit brackish water but only a few are

found in saline water. Killifishes are well known for their adaptability. Many species

inhabit bodies of water that dry up during summer (Annual killifish). A few species even

spend part of their life under a layer of ice, while the Desert Pupfish (Cyprinodon sp.) is

found in water with a temperature of 116.6 ° F (47C). Most of the killifish are small,

ranging from 2 to 3.5" (9cm). A few rare species exceed 8" (20cm).

Killifish are the egg-laying cousins of live bearing fish such as mollies and

guppies. There are about 500 species of killifish. Like their live bearing counterparts,

killifish are usually mosquito larvae eaters. Many killifish species are as brightly coloured

as salt-water fish and have incredible finniage. Some killies known as annuals spawn

every day, because by nature, when the ponds dry up, the eggs go into a hibernation phase

known as diapause. Killifish are divided into three general breeding groups of annuals,

semi-annuals, and non-annuals (plant spawners). Annual fish are all substrate (peat) or

bottom spawning fish. With the advent of the rainy season, the annual killifish hatch from

eggs deposited in the mud and decaying leaves, the result of the daily spawning of the

previous generation. Spawning is performed every day, just in case in the next rainy

season, when the first rains are insufficient to fill the pool. Species of annual killifish

xvii

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therefore grow and mature quickly, and so they can repeat the process before the ponds

dry up again between rainy seasons.

Semi-annuals live in areas which sometimes dry out to moist mud, but at other

times retain water throughout the dry season. They are therefore substrate (in the mud,

leaves, etc.) spawners and tend to live a little longer than the annual species. The non-

annuals, such as Aplocheilus lineatus, Aphyosemion sp. of killifish live in permanent

bodies of water and, in some cases, will live for upto five years. The non-annuals, or plant

spawners, can be bred using spawning mop method for higher yield and with water

incubation of the eggs. Most non-annuals killifish eggs hatch on an average of 21 days.

The family Aplocheilidae consists of two sub-families, Aplocheilinae (Old World

Rivulines) and Rivulinae (New World Rivulines). Included among the sub-family

Aplocheilinae are the following genera: Aphyosemion, Aplocheilus, Epiplatys,

Nothobranchus, Pachypanchax, and Pseudepiplatys. The sub-family Rivulinae includes

fish of the genera: Cynolebias, Cynopoecilus, Pterolebias, Rivulus, and Simpsonichthys.

Now a days interest in killifishes is not restricted to scientists, but it has spread

internationally leading to the formation of various Killifish Associations like American

Killifish Association (www.aka.org), International Killifish Association (www.killi.net),

with various killifish web pages like www.aka.org; www.killifish.f9.co.uk ;

www.killi.co.uk ; www.killies.net; www.killi.net ; www.killifish.f9.co.uk ;

www.sfish.com/kf, www.thearkfoundation. org/SAA . etc.

The present study on the killifish Aplocheilus lineatus throws more light on its

spawning periodicity and spawning potential, gonadal and gametogenic cycles,

embryogenesis, food and feeding habits, population dynamics and parasitic infestations.

xviii