1 -4`3 I

"1

REVIEW OF LITERATURE 1 .ptroduction

T

he family Cyprinodontidae comprises of many ornamental fishes.

Cyprinodontidae includes 50 genera with 300 species. The members of the family are egg laying toothed carps or minnows. The genera found in India are Aplocheilus and Aphanius. Four species of Aplocheihis (A. lineatus, A. blockii, A. dayi and A. panchax) are being reared as ornamental fishes. The most popular one is Aplocheilus lineatus.

1. 1. Reproductive characteristics of ornamental fishes Reproductive strategies of ornamental fishes have been reviewed by Wallace and Selman (1981), de Vlaming (1983), Wootton (1984), Mann et al. (1984), Balon (1990), Aida (1990) and Mills (1991). Rutilus rutilus spawned once in a year for several years. Alburnus alburnus spawned several batches within a year and Etheostoma raJlnesquei reproduced at 2 to 3 year intervals (de Vlaming, 1983; Bye, 1984; Weddle and Burr, 1991; McEvoy and McEvoy, 1992).

Spawning in cyprinodont fish is synchronized by semilunar tidal cycles (Taylor, 1984). Lunar or semi-lunar spawning is a feature of the reproductive cycle in many small cyprinodonts like F. olivaceus and F. euryzonus (Blanchard, 1996), F. parvipinnis (Espana et al., 1998), F. diaphanus (Chippett, 2003) and F. luciae (Kneib, 1978; Hardy, 1978). Wallace and Selman (1981) suggested that rise in temperatures triggered spawning for F. heteroclitus in Massachusetts. Cypnnodonts followed multiple and extended spawning strategy which was found in Fundulus heteroclitus (Taylor et al., 1979), F. grandis (Greeley and MacGregor, 1983), F. pulverus and Adinia xenica (Greeley, 1984), F. majalis (Taylor, 1984), F. similis (Greeley et al., 1986), and F. grandis (Greeley et al., 1988).

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1. 1. 1. Size and age at first sexual maturity The size and age at sexual maturity are the fundamental biological parameters used in stock assessments (Wang et al., 2003). Reyes and Ortega (2002) reported the initial sexual maturity of Betta splendens and Trichogaster trichopterus. Jacob and Nair (1983) reported that the minimum size at maturity of Macropodus cupanus was 18mm. The mean size at maturity of six Barbus sps viz Barbus nigrofasciatus was 37mm, B. bimaculatus 30mm, B. cumingi 40mm, B. titteya 22mm, B. dorsalis 53mm and B. vittatus 27mm had been reported by DeSilva etal., (1985). Popma and Masser (1999) reported the age at maturity of Oreochromis niloticus to be 5-6 months. Variation in the size between the sexes had also been reported. In Cichia monoculus, the male was 262mm at maturity whereas the female was 214 mm (Chellappa et al., 2003) whereas in Gambussia hoibrooki the male was 2.9mm compared to the female having a length of 13.2mm (Specziar, 2004). Some of the killifishes, in which the size/age at maturity was studied is listed in Table -1. Table I.

Published information on the size / age at maturity of some killifishes

'Species

Family

Adinia xenica

Fundulidae

Size / age at Study area!Reference maturity Gulf of Koenig and Livingston, Mexico

2OmmSL

1976

Fundulus luciae

Fundulidae

North Carolina

Aphyosemion gardneri

Aplocheilidae

Bloomington

Aphanius iberus

Cyprinodontidae South-west Spain

Males 1.7-2.4cm females 2.3-2.8cm.

Delgado et a/.,l988

Cynopoecilus melanotaenia

Rivulidae

Brazil

6-8weeks

Arenzon et al., 2002

Fundulus diaphanus

Fundulidae

Canada

+lyear, at 6cm,

Chippett, 2003

Notobranch ius furzeri

Aplocheilidae

Italy

0.08 to 0.13 yrs,

Female 3cm.

Kneib, 1978

9Odays

Kroll, 1984.

Valenzano et al.

Faster growing individuals matured earlier, than slower growing individuals (Alm, 1959). The correlation between the growth rate and age at sexual maturity had a negative relationship (Bilton etal., 1982; Saunders etal., 1982; Stearns, 1983; Gjerde and Refstie, 2

1984; McCormick and Naiman, 1984; Tveranger, 1985). Males of the family Poecilidae greatly reduced growth upon attainment of sexual maturity (Turner, 1941; Hughes, 1985). The males of Xiphophorus nigrensis matured at a large body size (Ryan and Causey, 1989; Morris and Ryan, 1990). Fundulus heteroclitus males attained sexual maturity at 30mm SL (Schmeltz, 1964; Kneib and Stiven, 1978). The diamond killifish Adnia xenica attained sexual maturity at about 20mm SL (Hastings and Yerger, 1971) and the maximum size was about 50mm (Koenig and Livingston, 1976). It was noted from the literature that the killifishes in general matured at an early size /age as 30mm in Fundulus luciae (Kneib, 1978) , 90days in Aphyosemion gardneri (Kroll, 1984), 6-8weeks in Cynopoecilus melanotaenia,(Arenzon et al., 2002), and 0.08 to 0.13 yrs in Notobranchius furzeri (Valenzano et al., 2006). In fishes like Aphanius iberus males (17mm) matured earlier than females (28mm) (Delgado et al., 1988).

1. 1. 2. Reproductive cycle The reproductive behaviour is geared to take advantage of environmental and other physiological factors which offer the greatest opportunities for survival and development of the new generation (Jacob and Nair, 1983). Ovarian weight was used by Nikolsky (1963) and De Vlaming et al., (1982) to index fish reproductive cycles since, before egg release, ovarian weight usually increased. Most fishes were seasonal breeders like Fundulus luciae (Kneib, 1978), Aphanius iberus (Delgado et al., 1988), Fundulus heteroclitus (Hsiao et al., 1994) Fundulus olivaceus and Fundulus euryzonus (Blanchard, 1996) Fundulus parvipinnis (Espana et al., 1998) and Fundulus diaphanous (Chippett, 2003)

This seasonality in breeding is regulated by the environmental factors through the endocrine glands, which results in synchronized maturation and spawning (Sehgal and

3

Sundararaj, 1970; Poston, 1978). Ozturk and Ikiz (2004) reported that Gambussia affinis bred during March to October in Turkey .Delgado and Rossomanno (1997) reported that breeding of Gambussia affinis occurred during May to September in Hungary. Jacob and Nair (1983) reported that Macropodus cupanus bred from September to April in Kerala. In tropical waters, climatic changes associated with the monsoon rains stimulated spawning (Pandian, 1970; Qazim, 1973; Siddiqui etal., 1976; Jacob and Nair, 1983; Van Oordt et al., 1987). According to Bennet (1967), the sexual cycle was adjusted in both sexes so that the spawning acts coincided. In killifishes, studies on various species showed that the breeding season exhibited different patterns. Fundu!us heteroclitus (Hsiao etal., 1994) and F. parvipinnis (Espana etal., 1998) bred during February to May. F. luciae reported by Kneib (1978) had the longest breeding season from January to August. Aphanius iberus bred from February to July (Delgado et al., 1988), F. olivaceus and Fundu!us euryzonus bred from March to August (Blanchard, 1996) whereas April to August was reported to be the breeding season for F. diaphanous (Chippett, 2003).

Reports of several workers showed that many freshwater ornamental fishes such as Poeci!ia mexicana (Monaco et al., 1978), Hyphessobrycon pulchripinnis (Nakatsuru and Kramer, 1982), Pterphy!lum scalare(Schewmann, 1990), Betta splendens (Sakurai et al., 1993) and Cichia monoculus (Chellappa et al., 2003) exhibited multiple spawning pattern. Several killifishes were also found to be multiple spawners such as Cynopoecilus melanotaenia (Arenzon et al., 2002) Lucania goodie(Fuller, 2001; 2002) Fundulus diaphanous(Chippett, 2003) and Fundulus heteroc!itus(Able and Hagan, 2003).

1. 1. 3. Gonadal cycle The cyclic development of gonads in fishes is influenced by photoperiod and temperature (Hyder, 1970; Siddiqui et al., 1976). Both male and female gonads

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underwent regular seasonal cyclical changes in size and weight (Delgado and Herrera, 1995). The development of gonads is used as an index of sexual maturation in fishes (Katano, 1990). Patterns of egg production (oogenesis) varied widely among fish species (Wallace and Selman, 1981). Ovary development began much earlier than the beginning of spawning (McDowall and Eldon, 1997). Spawning stage is characterized by the presence of the follicular epithelium around maturing and mature oocytes (Caramaschi et al., 1982).

In most teleosts, the testes are paired (Swarup and Srivastava, 1979; Kaul and Rishi, 1986; Joshi and Joshi, 1989), although in the Poecilids, they are combined into a single sac. The structure of the teleost testis may vary, but two main types were characterized; the lobular and the tubular type. The lobular type was the most common one which was present in the killifish A. lineatus. Spermatogenesis was explored in several fishes including C/arias batrachus (Lehri, 1967; Thakur, 1978), Channa guchua (Sanwal and Khanna, 1972), Labeo calbasu (Sehgal, 1971) and Labeo rohita (Mukhopadhyay and Sinha, 1986). In a majority of the Indian teleosts, spermatogenesis was controlled by temperature and photoperiod (Das and Subla, 1963; Rai, 1965b; Nayyar and Sundararaj, 1970; Sanwal and Khanna, 1972; Dixit and Agarwal, 1974; Kaul, 1975). Jacob and Nair (1983) reported five stages in the ovarian development in the larvivorous fish Macropodus cupanus viz, immature virgin, recovered spent, ripening, ripe and spent depending on the external appearance of the ovary. Treasurer (1990) observed nine ovarian stages: virgin, maturing virgin, developing early, developing late, gravid, spawning, spawning /spent, recovering/spent in the pike Esox lucius. DeSilva et al. (1985) observed six ovarian stages in six Barbus sps. Danson (1992) observed six ovarian and four testicular stages during the gonadal development in Synnodontis sps. under macroscopic examination. Joshi and Joshi (1989) reported four stages (resting

5

phase, early maturing phase, advanced maturing phase, in the testicular cycle of Puntius dukai on the basis of hi stomorpho logical characteristics. Ha and Kinzie (1996) reported five stages of gonadal maturation (ovaries with immature pre-vitellogenic oocytes, ovaries with vitellogenic oocytes, ovaries with hydrated oocytes, ovaries with atretic oocytes and post-spawn 'recuperating' ovaries) in Awaous guamensis based on microscopic observations. Testis was categorized in three maturation stages (immature, intermediate, mature). Palmer etal. (1995) observed seven stages of oocyte development (Chromatin nucleolus stage, early perinucleolus stage, late perinucleolus stage, yolk vesicle stage, rimary yolk stage, secondary yolk stage and tertiary yolk stage) in the freshwater drum Aplodinotus grunniens. Some of the killifishes, in which the spawning pattern was studied is listed in Table -2. Table -2.

Published information on the spawning patterns of some killifishes

Species

Family

Not hobranchius guentheri

Aplocheilidae

Stiid

Aiea Zanzibar

Spawning pattern

R "eference

Substrate spawner,, Multiple spawner

Haas, 1976

Epiplatys bfasciatus Aplocheilidae

Southern Sudan Prolonged spawning Guma'a, 1982

Fundulus grandis

Fundulidae

Alabama Gulf Coast

Repetitive spawning

Greeley and MacGregor, 1983

Adinia xenica

Fundulidae

Gulf of Mexico

Multiple spawner

Able, 1984

Fundulus zebrinus

Fundulidae

Kansas

Multiple spawner, batch spawning

Schmeidler and Brown, 1990

Rivulidae

New Jersey

Batch spawning

Scheel, 1990

Fundulidae

Maryland

Spawn year round

Hugg, 1996

Fundulus luciae

Fundulidae

North Carolina

Multiple spawner, batch spawners

Hugg, 1996

Cynopoecilus melanotaenia

Rivulidae

Brazil

Repeated spawner

Arenzon et al., 2002

Lucania goodie

Fundulidae

Peninsular Florida

Fundulus diaphanus

Fundulidae

Canada

Batch spawner and Multiple spawners Multiple and batch spawner

Fundulus heteroclitus

Fundulidae

New Jersey

Simpsonichthys constanciae Fundulus waccamensis

Multiple spawner

Fuller, 2001; 2002 Chippett, 2003 Able and Hagan, 2003

The ovaries of such multiple spawners passed through a series of stages like maturing, mature and ripe (Hems and Rabito, 1986). Oviparous fishes with group-

synchronous oocyte development spawned multiple clutches of eggs periodically in the reproductive season (Wallace and Selman, 1981; Hems and Rabito, 1986). Yolk deposition ceased as oocytes attained their full mass and began to ripen (Masui and Clarke, 1979; Wallace and Selman, 1985). However, in cyprinodonts yolk loading continued as oocytes began to ripen as in Funduizis heteroclitus (Wallace and Selman, 1985). In F. heteroclitus, oocytes ovulated continuously in an asynchronous ovary during the spawning season (Selman and Wallace, 1986).

1. 1. 4. Gonadosomatic Index The involvement of gonadal maturation in the spawning rhythm of both males and females was investigated by measuring the Gonadosomatic index (GSI). This index normalized gonad weight (Pickford, 1953) with respect to body weight (Gonad wt I Body wt) x 100 (Taylor et al., 1979). The Gonadosomatic index was used successfully to determine the reproductive season (Kanabashira et al., 1980; Agostinho et al., 1986; Azevedo et al., 1988; Arruda et al., 1993) in fishes. The GSI was used as an indicator of the seasonal reproductive cyclicity in neotropical species (Barbieri and Barbieri, 1983; Agostinho etal., 1986; Azevedo etal., 1988; Barbieri, 1989).

The seasonal change in the GSI corresponded to the abundance of egg-containing nests in the field (Kanabashira et al., 1980). In cyprinodonts GSI changes in male was parallel to the female. However males were not obviously cyclic during the breeding season (March to August) as in Fundulus grandis and Fundulus olivaceus (Greeley and MacGregor, 1983) and (February to May) in Fundulus heteroclitus (Hsiao et al., 1994) and Fundulus parvipinnis (Espana et al., 1998). In F. heteroclitus males with a GSI greater than 2.0 were designated as ripe (Kneib and Stiven 1978; Taylor, 1986; Leblanc et

7

al., 1997). In Aphanius iberus, the GSI of females ranged between 6.5 to 15.0 % and that of males from 0.5 to 2.0% (Delgado etal., 1988).

In F. grand/s the hydrated oocytes showed the maximum GSI of 7.5% whereas the mature female showed 3.04 to 7.39% (Hsiao and Meier, 1988). In general in killifishes there was an increase in GSI which resulted from an increase in the formation of hydrated oocytes anci ovulated eggs as in F. grand/s (Hsiao and Meier, 1988) Cynopoecilus melanotaenia (Arenzon et al., 2002) Lucania goodie (Fuller, 2001; 2002) F. diaphanous (Chippett, 2003) and F. heteroclitus (Able and Hagan, 2003).

1. 1. 5. Fecundity Fecundity was calculated as the number of eggs per female (Nikolsky, 1963; Lambert et al., 2003; Murua and Saborido-Rey, 2003). It is dependent on various factors like size, age and condition (Lagler et al., 1967). A large number of relatively small eggs appeared to be the favoured strategy among marine and freshwater teleosts (Jennings et al., 2001; Reyes and Ortega, 2002). The mean relative fecundity of the larvivorous fish Macropodus cupanus was 841 eggs (Jacob and Nair, 1983). The relative fecundity of the pike Esox lucius was observed by Treasurer (1990) to be 10-24 eggs. The fecundity of six Barbus species viz.: Barbus nigrofasciatus - 151-638, B. bimaculatus - 82-2366, B. cumingi - 233-1366, B. titteya - 28-201, B. dorsalis - 100-767 and B. vittatus - 86-825 eggs (De Silva et al., 1985). The number of eggs laid by the female was highly variable in different ornamental fishes like Betta splendens (Sakurai et al., 1993), Pomoxis nigromaculatus (Baker and Heidinger, 1994), Oreochromis niloticus (Popma and Masser, 1999), Cichla monoculus (Chellappa et al., 2003) and Gambussia affinis (Ozturk and Ikiz, 2004).

8

Fecundity in fishes was usually related to size (Bagenal, 1978; Kneib, 1986)) and various size (age) classes of fish did not contribute equally to population fecundity (Nikolsky, 1976). (Krumholz, 1948; Wilbur, 1977; Travis, 1983; Cheong etal., 1984). In multiple spawners such as mummichog, fecundity fluctuated during the reproductive period with peaks immediately before spawning events (Taylor etal., 1979; Kneib, 1986). Schmeidler and Brown (1990) reported the mean fecundity of Fundu!us zebrinus to be between 18 and 74 eggs. Annual, semiannual and non-annual killifishes laid their eggs in batches for two to three weeks in a spawning season (Hsiao and Meier, 1989; Hsiao et al., 1994). Some of the killifishes, in which the fecundity was studied is listed in Table -3.

Table 3.

Published information on the fecundity of some killifishes

Species

Family

Not obranchius guentheri

Aplocheilidae Zanzibar

Epiplatys bfasciatus

Aplocheilidae Southern Sudan absolute 15-35

Fundulus zebrinus

Fundulidae

Kansas

Fundulus luc,ae

Fundulidae

North Carolina

Rivulus marmora tus

Aplocheilidae Southeast Brazil 368425eggs

Lucania goodei

Study Area

Fecundity

Reference

2540eggs/ female/day

Haas, 1976

Mean fecundity I 8-74eggs 235eggs/female, 9-21 eggs/batch

Gumaa ,1982 Schmeidler and Brown, 1990 Hugg,1996 Davis, 1988

Peninsular eninsular Florida

1 0-20eggs/day for 7-Odays

Fuller, 2002

Fundulus diaphanus

Fundulidae

Canada

250-420eggs

Chippett, 2003

Fundulus heteroclitus

Fundulidae

New Jersey

10-25 eggs/batch

Able and Hagan, 2003

In killifishes too the number of eggs produced by a female was highly variable. Haas reported that Notobranchius guntheri produces 25-40 eggs /female/day. As many as 368-425 eggs/female were produced in Rivu!us marmoratus (Davis, 1980) whereas Fundu!us diphanus produced 250-420 eggs/female (Chippett, 2003).

1. 1. 6. Condition factor Condition factor (CF) is the individual deviation from the hypothetical ideal fish having an isometric growth (Weatherley, 1972); it permits a comparison between

individuals, populations and both sexes (Ricker, 1975). Different formulations of the condition factor based on somatic weight and gutted weight were reported (Miliner et al., 1991; Lambert and Dutil, 1997a, b; Bolger and Connolly, 1989; Blackwell et al., 2000; Lambert et al., 2003). The variability in the length-weight relationship over seasonal cycles and in relation to the spawning cycle in fishes was described by Heincke (1908). Value of K changed in plaice with length and during the spawning season (Thompson, 1917). The relationship between K and length varied seasonally due to spawning (Thompson, 1942). Prior to the spawning season the value of K increased with length and also K decreased with maturity. Thompson (1942) called K the ponderal index and suggested that variations in K reflected not only the spawning state but also changed in appetite and general condition.

1. 1.

7.

Courtship behaviour

Different patterns of reproductive behaviour among fishes have been described both in aquaristic (Meder, 1955; Foersch, 1956) and in scientific literature (Costa and Belote, 2002). A sequence of reproductive behaviours was defined, which includes five distinct stages: 1) Courtship displays; 2) Invitation; 3) Submerging; 4) Spawning! Fertilization; 5) Emerging (Costa and Belote, 2002).

Herb et al. (2003) described gill cover erection as the courtship display in the males of Betta splendens (Jaroensutasinee and Jaroensutasinee, 2001; 2001a; 2003). Courtship behaviour in Nothobranchius guntheri includes looping, steering and herding (Echelle, 1973; Haas, 1976). Barlow (1961) and Liu (1969) described the contacting movements and contacting patterns of Nothobranchius guntheri. Haas (1976) classified the reproductive behaviour of Nothobranchius guntheri as courting approach, nuzzle-

FD

sidle, clasp and jerk. Fuller (2001) observed the breeding behaviour in Lucania goodie (Breder and Rosen, 1966; Foster, 1967).

1. 1. 8. Spawning sex ratio The male and female ratio during spawning is the spawning sex ratio (Shapiro et al., 1993). Doutrelant and Gregor (2000) reported that when two males and a female of Betta splendens were left in an aquarium, both the males had aggressive interactions and started fighting. The female visited the winner for courtship. He reported the spawning ratio as 1: 1. Constantz (1989) initiated cross with 1 female: 2 males (Poeciliopsis sps.) in 10 gallon aquaria with one-inch gravel substrate. Female topminnows can be fertilized by multiple males, even within a single brood (Hurt and Hedrick, 2003; Hurt et al., 2004). Ankley etal. (2001) used 1 female for 2 males for breeding zebra fish.

1. 2. Early life history 1. 2. 1. Fertilization Success of fertilization depends on clutch size (Buckley et al., 1991; Solemdal et al., 1995), but not on male size (Rakitin et al., 1999). Fundulus heteroclitus exhibited reduced fertilization success in freshwater and low salinity waters. The fertilization success in freshwater was only 9% (Rao, 1971). Chippett (2003) reported that the fertilizable life of a Fundulus heteroclitus egg is 1 5-20minutes. Beyond this time the percentage of successfully fertilized eggs becomes very small, because eggs became artificially activated, developing a perivitelline space after about 20 minutes in seawater. In teleost fertilization, the sperm entered the ovum through a micropyle, which in Fundulus consisted of a single opening in the chorion (Brummett and Dumont, 1981) at the bottom of a slight depression.

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1. 2. 2. Egg characteristics Most freshwater fishes, particularly cyprinids (carps etc.), produced demersal eggs. In the freshwater forms the eggs (ova) either adhered to aquatic plants (phytophilic) as in killifishes, some to foreign body or they were deposited in nets (Shafi, 2000). Mature eggs of Fundulus luciae were big and translucent with a pale yellow colouration, lipid droplets at one pole, and chorionic filaments (Kneib, 1986). Some of the killifishes, in which the egg size was studied is listed in Table -4. Table 4.

Published information on the egg size of some killifishes

Species

Family

Study area

Egg size (dia) Reference

Adinia xen:ca

Fundulidae

Gulf of . Mexico

1.5-2.5mm

Fundulus luciae

Fundulidae

North Carolina 1.7-2.2 mm

Hardy, 1978

Fundulus majalis

Fundulidae

California

2-3mm

Able, 1984

Notropis nubilus

Cyprinidae

Southwest Missouri

Fertilized egg 2.1mm

Fowler et al., 1984

Aphyosem ion gardneri

Aplocheilidae

Bloomington

1.3-1.6mm

Kroll, 1984.

Fundulus grandis

Fundulidae

Southern Louisiana

1.5-1.9mm

Hsiao and Meier, 1988

Aphanius iberus

Cyprinodontidae South-west Spain

0.45-1.75mm

Delgado et al., 1988

Fundulus heteroclitus

Fundulidae

New Jersey

1.5-2.04 mm

Hsiao etal., 1994

Fundulus olivaceus Fundulus euryzonus

Fundulidae

Southeastern United States

0.5-2.1mm

Blanchard, 1996

Fundulus parvipinnis

Fundulidae

Mexico

2.3-2.8mm

Espana et al., 1998

Fundu/us diaphanus

Fundulidae

Canada

Cynolebias viarius

Rivulidae

Uruguay

Fertilized egg 2mm Fertilized egg 1.7mm

Koenig and Livingston, 1976

Chippett, 2003 Arezo et al., 2005

The chorion of the eggs of Japanese medaka Oryias latipes was transparent with many filaments that caused them to cluster together at the vent of the female (Albert, 1981; Britz and Canbrat, 2001). The yolk was golden yellow with several small oil droplets that eventually coalesce into a large single globule in Oryias latipes (Albert, 1981). The eggs of Pygmy angelfish were spherical and contained a single oil globule and

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eggs hatched after 18 hours at 24°C (Holt and Riley, 1995). Zona radiata and jelly coat with fibrils were described in Fundulus heteroclitus by Eigenmann (1980). Kaighn (1964) found four to five layered chorion in F. heteroclitus, 6-8.im thick with 0.56 jim pores Follicles of the gulf killifish Fundulus grandis 1.9 mm in diameter or larger were considered "ripe" (the average diameter of ovulated eggs was 2.0mm) (Greeley and MacGregor, 1983). Blanchard (1996) reported that hydrated eggs of F. euryzonus were more transparent, contained oil droplets concentrated at one pole of the egg, and had long adhesive filaments attached to the external surface. Morin and Able (1983) reported the presence of a number of oil droplets in the egg of Fundulus heteroclitus. Fowler et al. (1984) reported that fertilized eggs of Notropis nubilus were spherical, translucent, demersal and non-adhesive. Adhesive eggs occur in Notropis analostanus, N chalybaeus, N galacturus and N. whipplei (Carlander, 1969), N. macu/atus (Cowell and Barnett, 1974) and N rube//us (Reed, 1958). Harrington (1947a, b) reported that N. bfrenatus eggs are adhesive when unfertilized but non-adhesive after fertilization.

1. 2. 3. Early life history The embryonic and post-embryonic development of Aphanius fasciatus was studied in relation to different environmental conditions (Leonardos and Sinis, 1997b). Greeley and MacGregor (1983) reported that the incubation period for F. grandis was 14 ± 1 day. Kneib and Parker (1991) reported in F. heteroclitus and Taylor etal. (1977) in F. luciae that embryonic development was completed in 7-8days (at 25°C), and hatching occurred 12-14 days after the eggs were spawned (Radtke and Dean, 1979). Yamamoto (1967) reported the embryonic development of Oryzias latipes. Koenig and Livingston (1976) reported the embryonic developmental stages of the diamond killifish Adinia xenica 13

Cyprinodontid fishes, were characterized by a reversible developmental arrest of variable duration (diapause) at one or more points (Wourms, 1972a; 1972h; 1972c) and (Matias and Markofsky, 1978). In Aphyosemion gardneri the young developed rapidly and reached sexual maturity in less than 90 days (Kroll, 1984). Arezo et al. (2005) reported a different developmental pattern in Cynolebias viarius. The embryos of Cynolebias viarius showed reversible arrests (diapauses) at different stages (Wourms, 1972a, b, c; Ballard, 1981). Developmental studies, including cell behaviour during early development, were reported for three species: Cynolebias constanciae Myers, Cynolebias whitei Myers and Cynolebias nigripinnis Regan (Wourms, 1972b; Carter and Wourms, 1991). Some of the killifishes, in which the incubation period was studied, is listed in Table -5. Table 5.

Published information on the incubation period of some killifishes

Species

Family

Study area

Incubation Period

Fundulus heteroclitus

Fundulidae

New Jersey

6.95 days

Austrofundulus myersi

Fundulidae

Australia

33 days

Wourms, 1972a

Fundulus grandis

Fundulidae

Alabama Gulf Coast

14 ± 1 day

Greeley and MacGregor, 1983

Nothobranchius korthausae

Aplocheilidae

17 days

Van Haarlem, 1983

Aphyosemion gardneri

Aplocheilidae

Bloomington 17 days

Cynolebias nigripinnis

Rivulidae

Cynolebias viarius

Rivulidae

32 days Uruguay

40 days

Reference Armstrong and Child, 1965

Kroll, 1984 Carter and Wourms, 1991 Arezo et al., 2005

Among killifishes, the shortest incubation period of 14±1 day was reported in Fundulus grandis by Greeley and MacGregor (1983). In Notobranchius korthausae and Aphyosem ion gardneri, the incubation period was found to be 1 7days (Van Haarlem, 1983). Austrofundulus myersi and Cynolebias nigripinnis had 32 days (Carter and

14

Wourms, 1991). The longest incubation period of 40days was reported in Cynolebias viarius by Arezo et al., (2005).

There was considerable variation in the number of embryonic stages in killifishes. Arezo et al., (2005) and Arezo et al., (2002) have reported 13 embryonic stages in Cynolebias viarius and Cynolebias melanotaenia respectively. Kroll (1984) has reported 19 stages in embryonic development of Aphyosemion gardneri. The maximum numbers of stages were reported for Adnia xenica by Seegers (2000) to be thirty—six.

1. 3. Food and feeding habits Foraging patterns vary within and among species, and in response to changes in the food resource. Schoener (1974) suggested that factors influencing foraging include diet, time, space and group size. It was reported by most of the authors that insect and mosquitoes formed the major part in the diets of Cyprinodontiformes. Adult mummichogs primarily fed on a variety of prey, particularly small crustaceans (amphipods, tanaids, and copepods), juvenile fish shrimp, and polychaetes, as well as algal-detritus conglomerate, insects, small crabs, detritus of marsh grass Sapartina sp., and fecal pellets (Kneib and Stiven 1978; Radtke and Dean 1979; Gobell, 1998). Larval mummichogs fed on live, 24 hour post hatch brine shrimp nauplii (Boyd and Simmonds, 1974; Beck and Bengston, 1979; Radtke and Dean, 1979; Hirshfield, 1980; Black, 1995; Gobell, 1998). Harrington and Harrington (1961) studied the diet of the marsh killifish Fundulus confluentus and the Gulf killifish F. grandis and found that microcrustaceans were the most abundant food item for F. grandis (Rozas and LaSalle, 1990). F. confluentus had microcrustaceans and ploycheates to the maximum. The diets of F. luciae and F. heteroclitus consisted mainly of small crustaceans, mollusks and annelids (Hildebrand and Schroeder, 1928).

15

Campton and Gall (1988) reported that Gambussia affinis, a native of southeastern United States and North eastern Mexico, was the most widely distributed freshwater fish and was probably believed to be the most widely disseminated natural predator in the history of biological control (Nelson and Keenan, 1992; Bokiund, 1997; Rupp, 1997; Delgado and Rossomanno, 1997). Some of the killifishes in which the food and feeding habits were studied is listed in Table-6. Table 6.

Published information on the food and feeding habits of some killifishes Family

Species

Austrolebias nigripinnis Rivulidae

Interfrence

Reference

Mills and Vevers, Germany Mosquitoes, crustaceans, plankton, annelids 1989 Insect, prawn, shrimp, Minello et Texas crustaceans, zooplankton, al., 1989 ploychaetes, non-annelids

Fundulus grandis

Fundulidae

Fundulus heteroclitus

Fundulidae

Aplocheilus dayii

Aplocheilidae India

Early stages of fishes, zooplankton, fish eggs, insects

Taiwar and Jhingran, 1991

Fundulus grandis

Fundulidae

Insect, prawn, zooplankton

Ley etal., 1994

Aplocheilus sinensis

Aplocheilidae Korea

Mosquito (Anopheles), plankton

Kim et al., 2002

Fundulus heteroclitus

Fundulidae

NewBenthic micro algae Jersey

Currin et al., 2003

Fundulus heteroclitus

Fundulidae

America Grass shrimp

Kunz and Pung, 2004

Canada

Florida

Insects, mosquitoes, zooplankton Pauly, 1989

Introduction of Gambussia affinis in California rice fields in the rainy season caused considerable reduction in the larvae of Culex tarsalis and Anopheles freeborni (Hoy et al., 1972). Fundulus diaphanus fed in all levels of the water column despite the superior position of the mouth (Keast and Webb, 1966). Smaller individuals ate chironomid larvae, ostracods, cladocerans, copepods and small quantities of amphipods and some flying insects while larger individuals fed on the above and also took Odonata and Ephemoptera nymphs, molluscs, tubellarians and small crustaceans (Keast and Webb, 1966; Baker-Dittus, 1978; Chippett, 2003). Kneib (1978) reported that the gut content of Fundulus luciae showed small crustaceans (copepods, tanaids and amphipods) and insects

16

(hemipterans and small dipterans). Gut content analysis of Aplocheilus sinensis (Kim et al., 2002), Austrolebias nigripinnis (Minello et al., 1989) and Fundulus grandis (Mills and Vevers, 1989) revealed that the main constitution was mosquito larvae.

The diet of freshwater ornamental fishes and killifishes was varied including chironomid larvae, glass worms, krills, mosquito larva etc in Pterphyllum scalare (Wakes and Ben, 1991) Beita splendens (Sakurai et al., 1993) Synodontis macrostigma (Winemiller and Kelso-winemiller, 1996) Hyphessobrycon pulchripinnis (Cole et al., 1999) and Brachydanio rerio (Sawant etal., 2001).

1. 3. 1. Hepatosomatic index The Liver is an important storage organ for fuel reserves, which is used during reproduction. An analysis of the seasonal changes in Hepatosomatic Index (HSI) in relation to the annual gonadal cycle had become imperative (Patil and Kulkarni, 1994; Ruchon et al., 1995). The relative size of the liver tended to reflect the recent feeding history; a larger ration tended to produce a large liver (Heidinger and Crawford, 1977). Even though studies pertaining to the reproductive cycles of Indian freshwater fishes were available (Sinha and Rastogi, 1967; Sundararaj and Goswami, 1968; Guraya et al., 1975; Siddiqui et al., 1976; Malhotra et al., 1978; Srivastava, 1979, 1980; Jacob and Nair, 1983), the seasonal cycles of organic reserves in relation to the reproductive cycle were observed only in a few fishes (Piska and Waghray, 1989).

1. 4. Population dynamics Population dynamics is a division of the general theory, which deals with the laws of reproduction, growth and the causes of death of living organisms (Nilkolsky, 1969).

17

1. 4. 1. Lifespan Several cyprinodontiforms were short lived especially those small species that live in temporary waters and die after spawning (Margalef, 1983). Their relatively short longevity was characteristic of cyprinodonti forms (Nikolsky, 1963). Berthou and Amich (1992) reported the age of an Iberian cyprinodont, Aphanius iberus (Cuv and Val.) as two years. The cyprinodonti form fishes Cyprinidon macularis eremus and Fundulus heteroclitus (L.) lived up to four years (Kneib and Stiven, 1978; Samaritan and Schmidt, 1982; Miller and Fuiman, 1987).

Nothobranchius furzeri showed a more limited lifespan when reared under laboratory conditions than in the natural environment (Liu and Walford 1966; Markofsky and Perlmutter 1972, 1973; Genade et al., 2005). Valdesalici and Cellerino (2003) recorded the shortest ever the lifespan in Nothobranchius furzeri for a vertebrate. The annual fish N. furzeri had a maximum lifespan of only 12 weeks when cultured at 25°C under laboratory conditions. In nature N. furzeri had a life span of three months (Wood et al., 2004; Massingham and Goldman, 2005; Evason et al., 2005). Valdesalici and Cellerino (2003) reported that the life span of N furzeru was short even when compared with other species of annual fishes (Liu and Walford 1966; Markofsky and Perlmutter 1972; Wood et al., 2004; Massingham and Goldman, 2005; Evason et al., 2005; Genade et al., 2005). All fishes of the genus Nothobranchius were known for being fast growing and short lived, often living for less than one year (Scheel, 1990). N. furzeri represented the lower end of the lifespan spectrum in a taxon of organisms adapted for fast growth (Kirkwood, 2002; Wood et al., 2004; Massingham and Goldman, 2005; Evason et al., 2005; Genade et al., 2005). The lifespan of zebrafish Danio rerio was close to five years (Driever et al., 1996; Amsterdam et al. 1996; Nasevicius and Ekker, 2000; Gerhard et al.,

18

2002; Kishi et al., 2003; Murtha and Keller, 2003; Herrera and Jagadeeswaran, 2004; Muller, 2005).

1. 4. 2. Age and growth Age information formed the basis for calculations of growth rate, mortality rate and productivity (Campana and Thorrold, 2001). Several calcified structures produced periodic growth increments useful for age determination in fish. Though scales (Robillard and Marsden, 1996), vertebrae (Brown and Gruber, 1988), fin rays (Cass and Beamish, 1983), cleithra (Casselman, 1990) and opercula (Baker and Timmons, 1991) were used to determine annual age, otolith was frequently used for age determination (Secor et al., 1995). In the present investigation also otoliths were exclusively used for determination of age Aplocheilus lineatus. Campana and Thorrold (2001) estimated over one million fish worldwide in 1999, using scales and otoliths. Several reviews of age validation techniques suitable for annual (Cailliet, 1990; Beamish and McFarlane, 1987, Campana, 1999, 2001) and daily ages (Brothers, 1979; Campana and Neilson, 1985; Geffen, 1987, 1992) were published.

1. 4. 3. Length-weight relationship The length weight relationship is one of the standard methods yielding authentic biological information (calculating weight from length of fish, growth of fish and also evaluating the condition factor). Le Cren (1951) contended that the length-weight relationship was used to determine the mathematical relationship between two length and weight, and to measure the variations from expected weight for length of individuals or group of individuals or group of animals. Length-frequency analyses showed the significant difference between males and females and confirmed the sexual dimorphism in a species (Mazzoni and Caramaschi, 1995). Seasonal changes in the length and weight frequency distribution of fishes demonstrated the animal life-cycle and the exact 19

spawning season of the fish (Morgan et al., 1995). The trends executed by the monthly length-frequency distributions in Nannatherina baistoni (Morgan et al., 1995) and Galaxiella nigrostriata (Pen et al., 1993) demonstrated that they typically had a one year life cycle. The length-weight relationship was described in Rutilus rutilus (Papageorgiou, 1979), Zacco temmincki (Katano, 1990), Synodontis sp. (Danson, 1992), Z. pachycephalus (Wang et al., 1995) and Serrasalmus spilopleura (Lamas and Godinho, 1996).

1. 4. 4. Inter/intra specific relationship Schmeidler and Brown (1990) assessed the intraspecific variation in the lifehistory in Fundulus zebrinus from three rivers. Species composition and abundances were observed to change randomly with environmental fluctuation (Starrett 1950, Harrell 1978, Matthews and Hill 1980, Ross et al., 1981). Extensive variation in egg size was reported from populations of F. heteroclitus (L) along the Atlantic coast of North America (Marteinsdottir and Able, 1992). In general, F. heteroclitus macrolepidotus, occupying the northern coastal waters of the Chesapeake and Delaware Bays, had relatively smaller eggs than F. heteroclitus collected from more southern coastal locations (Marteinsdottir and Able, 1992). In addition, several authors had noted marked geographic variation in the chorion morphology in F. heteroclitus (Brummett, 1966; Boyd and Simmonds, 1974; Able and Castagna, 1975; Hardy, 1978; Dumont and Brummett, 1980).

1. 4. 5. Sex ratio The sex-ratio of the population is analyzed to find out whether it deviates significantly from the hypothetical distribution of 1:1 or not (Siddiqui etal., 1976). The sex ratio can vary between populations, year-classes, and even within a single year-class. The first fish to mature and enter the spawning stock were males because they usually 20

matured earlier than females (Wang et al., 2003). Sex-ratio also revealed the preponderance and synchronized activity of females and males during spawning (Katano, 1990). Sex-ratio varied with the size of the fish (Babiker and Ibrahim, 1979). Leonardos and Sinis (1999) reported that the overall sex ratio ofAphaniusfasciatus in the Mesolong and Etolikon lagoons was 2.44: 1. Leonardos and Sinis (1997b) reported that the sex ratio for newly hatched fry was I :1. At Tar Landing Bay the sex ratio in F heteroclitus was 1:1 until maturity, then females were favoured (Kneib, 1986). The survival rate was greater for females than males (Leonardos and Sinis, 1999). Espana et al. (1998) reported that the natural mortality for Fundulusparvipinnis was 2.01 annually.

1. 5. Trematode infestation Parasitic infestations varied among geographic locations and habitats (Sogandares-Bernal and Lumsden, 1964; Addison et al., 1988; Mulvey et al., 1991, Faliex and Morand, 1994) and in a single location, across years (Dronen, 1978; Anderson and Gordon, 1982; McCallum and Anderson, 1984; Scott, 1987; Adler and Kretzschmar, 1992). Schroeder and Leigh (1965) reported the presence of Ascocotyle pachycystis in Cyprinodon variegatus (Heterophyidae) throughout the southeastern United States. Schulz and Schoonbee (1999) reported that the ecto and endoparasites in the shortfln minnow Barbus brevipinnis had annual infection cycle. The highest infection was recorded for trematode cysts in the liver of Barbus brevipinnis (Schulz and Schoonbee, 1999).

Landsberg and Lom (1991) observed specimens ofMyxobolousfunduli in gills of Fundulus heteroclitus, F. majalis and F. diaphnus. Other parasites observed on the gills of Chesapeake Bay mummichogs were the monogenean Gyrodactylus stephanus (Hargis, 1955) and digenean metacercariae of Phagicola diminuta (Stunkard and Uzmann, 1955).

21

Fournie and Overstreet (1993) reported the occurrence of sporocytes of Catlytospora funduli in Antheriformes which included Cyprinodontidae (killifishes; Fundulus spp. and Cyprinodon variegatus), Aplochei Iidae, Poeci Ii idae, Adrianichthyidae, and Antherinidae (Pellerdy, 1974; Dykova and Lom, 1981; Overstreet et al., 1984). Janovy and Hardin (1988) reported the prevalence of seven parasites in Fundulus zebrinus (Pisces: Cyprinodontidae) in the Platte River. Table 7.

Published information on the trematode infestation in some killifishes

Species

Family

Aphanius dispar Aplocheilus • melastigma Aplocehilus • melastzgma

Study area

Parasite

Reference

Cyprinodontidae Israel

As ymphylodora fishelsoki

Fischthal, 1979

Aplocheilidae

India

Kofoidella aplochezius:

Rama et al., 1979

Aplocheilidae

Central America

Allocread:umfasczatusz Madhavi, 1980

Hawkins et al., 1983 Calyptospora Foumieet al., Fundulus nottiz Fundulidae North America emprzstica 1985 Central Posthodiplostomum Madhavi and Aplocheiluspanchax Aplocheilidae America grayzz Rukumanj,1992 Coleman and Cyprinodon varzegatus Florida Ascocotyle pachycystzs Travis 1998 Not ho branchi us Lom and • . Aplocheilidae Czechoslovakia Nucleospora secunda rubrzpznnzs Dykova, 2002 Abdallah and Aphaniusfasciatus Cyprinodontidae Italy Bucephalus anguillae Maamoun, 2002 • Crassiphiala Ward eta L, Fundulus diaphanus Fundulidae Leeds (UK) bulboglossa 2002 Kunz and Pung, Fundulus heteroclztus Funduh dae America (GA) Mzcrocephalus turgzdus 2004 Fundulus grandzs

Fundulidae

North America Ezmerzafiindulz

• . Fundulus sciadzscus

Fundulidae

Western Nebraska

. Helt et al., PhyllodzstomumJiinduh 2003

Chandler et al. (1995) reported the presence of two digenean parasites Diplostomulum and Neascus in Poecilia gil/u. Eimeria funduli primarily infected hepatocytes of killifishes, required the grass shrimp Pa/aemonetes pugio holthuis to complete its life cycle, and sporulated within host tissues (Solangi and Overstreet, 1980). Duszynski et al. (1979) described some ultra structural features of Eimeria funduli oocysts isolated by sugar flotation from homogenized tissues (Hawkins et al., 1983).

22

Madhavi (1980) compared the parasitic fauna of Aplocheilus panchax and Aplocheilus melastigma and found 13 and 10 parasites respectively.

The infestation of killifishes by trematodes was reported by several workers. Aphanius dispar was infected by Asymphylodora fishelsoki (Fischthal, 1979), Aplocheilus melastigma by Kofoidella aplocheilusi (Rama et al., 1970), and Allocreadium fasciatusi

(Madhavi 1980), Aplocheilus panchax by Posthodiplostomum grayii. Other workers had also reported trematode infestation in killifishes (Lom and Dykova, 2002, Abdallah and Maamouri , 2002, Ward et al., 2002, Helt et al., 2003, Kunz and Pung, 2004).

23

OBJECTIVES OF THE PRESENT RESEARCH The objectives of the present research are to 1.

study the spawning periodicity and spawning potential (fecundity) of the killifish Aplocheilus lineatus.

2.

understand the pattern of gonad development cycles of A. lineatus.

3.

study the embryonic development of A. lineatus.

4.

identify the food and feeding habits of juvenile, pre-adult and adult

A.

lineatus.

5.

study the population dynamics of A. lineatus.

6.

study the parasitic infestations in A. lineatus.

26

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