Embryonic and Larval Development of the Striped Snakehead Channa Striatus
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Taiwania, 52(1): 84-92, 2007 Embryonic and Larval Development of the Striped Snakehead Channa striatus K. Marimuthu(1,3) and M. A. Haniffa(2) (Manuscript received 4 February, 2006; accepted 28 May, 2006) ABSTRACT: The present study elucidated the embryonic and larval development of snakehead Channa striatus from fertilization until metamorphosis. The snakehead was successfully bred in the laboratory by injecting ovaprim, a synthetic hormone (0.5 mL/kg body weight). Spawning took place 24-26 hrs after the hormone injection. The fertilized eggs were floating, non-adhesive and straw yellow in color. The average diameter of fertilized eggs ranged from 1.20-1.40 mm. Incubation periods was about 23-24 hr at a temperature of 29 ± 1°C. The percentage of hatching varied from 80-85. The newly hatched larva was 3.4 ± 0.2 mm in length. The yolk absorption was completed within three days after hatching. The larvae metamorphosed into juveniles within 20 days after hatching. KEY WORDS: Channa striatus, early embryonic, larval development, metamorphosis. INTRODUCTION ponds at densities of 40-80 fish/m2 with annual yields ranging from 7-156 tonnes ha-1 (Wee, 1982), The primary concern of any fish hatchery system although snakehead culture, is not practiced in a well is to produce the maximum number of the highest defined way in India as Indian Major Carps. Existing quality seeds and fingerlings from the available reports on larval development and behavior of C. broodstock. This is particularly important in the striatus are scarce with the exception of its biology farming of snakeheads because their wild seed and life history (Parameshwaran, 1975; collection is very much limited due to monsoon Parameshwaran and Murugesan, 1976a, b). The failure (Haniffa et al., 2000; Marimuthu et al., 2001a, larval development of other air breathing fish species b). Embryonic development and larval development viz., Channa marulius (Mookerjee, 1945) Channa studies besides providing interesting information in punctatus (Banerji, 1974; Marimuthu., 2002); itself are imperative and consequential to the Anabas testudineus (Moitra et al., 1987; Hughes et successful rearing of larvae for large scale seed al., 1986); Clarias batrachus (Thakur, 1976 and production. The observations made after studying 1980); Heteropneustes fossilis (Thakur et al., 1974) fish eggs, embryonic and larval development in Monopterus albus (Singh et al., 1990); Clarias fisheries sciences, aquaculture, taxonomy and gariepinus (Bruton, 1979; Verreth et al., 1992; ecology have been much highlighted (Blaxter, 1974). Segner et al., 1993); C. macrocephalus (Mollah and The striped snakehead Channa striatus, a Tan, 1982) have been reported. The embryonic and carnivorous air breather, is one of the valuable food larval stages are considered very sensitive indicators fishes in the inland regions of India and hence has a of environmental disturbances. They are also good culture potential. The candidate species can indispensable in the study on ontogeny and survive in harse environments with low dissolved phylogeny of their families (Legendre and Teugels, oxygen and high ammonia (Ng and Lim, 1990; Qin et 1991; Verreth et al., 1992). In addition such studies al., 1997) and therefore are often cultured in grow out on larval development of any cultivable species can __________________________________________ be useful in directing the husbandry efforts of fish 1. Department of Biotechnology, Faculty of Applied Sciences, farmer to the specific state and requirements of each Asian Institute of Medicine, Science & Technology, 2, larval stage. This is necessary to optimize larval Persiaran Cempaka, Amanjaya, 08000 Sungai Petani, Kedah Darul Aman, Malaysia. growth and survival. Therefore the present study has 2. Centre for Aquaculture Research and Extension, St. Xavier's been conducted and provides detailed information College, Palayamkottai, Tamilnadu, 627 002, India. about the embryonic and larval development of 3. Corresponding author. Email: [email protected] / striped snakehead C. striatus. [email protected] *This article is adopted from Zoological Taiwanica which was joined into Taiwania since 2006. MATERIALS AND METHODS March, 2007 Marimuthu and Haniffa: Channa striatus 85 The fertilized eggs of C. striatus were obtained The yolk is capped by a distinct blastodisc and from induced breeding of both male and female by an contains an oil globule liable to disintegration to 4-6 intramuscular injection of ovaprim at 0.5 mL/kg body globules, unequal in size (Fig. 2). The detail of the weight. Each breeding set consists of two males and development of fertilized eggs until hatching is one female. Hormone administered fishes were elaborated in Table1. released into earthen breeding pond (3×3×1 m). Aquatic macrophytes like Eichhornia crassipes and Embryonic development Hydrilla verticillata were provided into the breeding The first cleavage that divides the blastodisc into pond for hiding purposes. Spawning behavior of two blastomeres occurred within 15-20 min after hormonally induced fishes was closely observed. fertilization. The segmentation was typically After spawning, the fertilized eggs were carefully meroblastic. The second cleavage followed within 15 collected from the breeding tank using a 500 ml min and within another 30 min the 16 celled stage beaker and transferred to a glass aquarium containing was reached. As successive cleavages occurred the 15 L of water under gentle aeration. The water quality blastomeres decreased in size and the morula stage parameters including temperature 29 ± 1°C; was reached between 1.30-2.0 hr after fertilization dissolved oxygen 5.2 ± 0.5 and pH 7.0-7.3 were (Fig. 3). At about 5-6 hrs of fertilization the embryo recorded in the breeding pond and larval rearing tank attained blastula stage. After half an hour, the spread throughout the experimental period. After yolk sac of blastoderm was evident and 6 hrs after fertilization absorption the larvae were fed adlibitum twice per it was flattened at the top resulting in the formation of day with zooplankton (predominantly rotifers and the germinal ring (Fig. 4). Embryonic shield moina). Developing eggs were sampled every hour appeared within next 2 hrs and by that time more than during the first 24 hours and every 4 hours during the half of the yolk was invaded and at this stage the head next three days and then only once a day until and tail ends of the embryo became clearly metamorphosis. The sampled eggs and larvae were distinguishable. Gastrulation was in progress fixed in 4% formalin for further observations. In the approximately 9.30 hrs after fertilization and the present study, the developmental stages were divided blastopore was evident. In another 30 min yolk into embryonic, larval and post larval development. invasion was completed and the blastopore was The embryonic stage occurs inside the chorion and almost closed. ends in hatching. The larval stage is characterized by nutritive contribution by the yolk sac and the stage Differentiation of embryo ends when the larva becomes capable of exogenous Neural stage feeding. The post larval stage begins immediately on Observation made at 10.30-11.00 hrs revealed that absorption of the yolk sac and is characterized by antero-posterior axis was distinguishable, cephalic autonomous feeding. The age of the larvae was portion being broader and embryonic rudiment denoted as hours after activation. Measurements of became distinct with two somites. The anterior egg diameter and standard length were made using protuberance formed a head fold and the posterior ocular micrometer. The total lengths of 10 part elongated further to form tail fold. By the time individuals were measured at each sampling time (TL maximum diameter of the coiled embryo was 0.958 is the length from the tip of snout to the end of the mm. The eye vesicles were demarcated. About 6-8 caudal fin; Crawford, 1986). The mean total length somites were formed after 14 hrs and optic cups were was also calculated and recorded. The observation of clearly distinguished (Fig. 5). In the 15-16 hr embryo, the larvae was carried out under a binocular more than three fourth of the egg peripherical space microscope (Nikon Eclipse E400) till the end of the was occupied by the embryo. Number of mesodermal larval period. somites gradually increased from 8 to 10 and pigmentation was noticed in somites. Notochord was RESULTS more clearly seen and the fore mid and hind brain region were also noticed. Cephalic portion was Description of fertilized eggs broadened and embryo was embedded in the yolk The spawning was noticed within 24-26 hrs after mass all over its length. At 18 hr old embryo, the the hormone injection. Fertilized eggs of C. striatus whole space inside the egg was fully occupied by the were free floating, spherical, non-adhesive embryo. The mesodermal somites ranged from 12-15 translucent and straw yellow in color (Fig. 1). The in numbers. Blood circulation was observed. diameter of the fully swollen fertilized eggs varied Ectodermal thickening to form lens of the eye was from 1.20-1.40 mm. The egg proper is brownish in indicated. The caudal tail region started to detach color having an average diameter of 850 ± 10 μm. from the yolk mass. Embryonic fin fold appears, and 86 TAIWANIA Vol. 52, No. 1 Table 1. Embryonic development of Channa striatus. Time after Stage Description spawning 0 min Fertilized egg Eggs were free floating, spherical, non adhesive, transparent and straw yellow in color. The diameter of the fertilized eggs varied from 1.20 mm-1.40 mm. 15 – 20 min 2 Cell stage First cleavage 30 – 50 min 16 Cell stage Fourth cleavage 1.30 – 2.0 hr Morula Blastulation progresses to form a multicellular blastodisc. 5.00 – 6.00 hr Blastula Embryonic shield formed, more than half the yolk invaded, anterior and posterior differentiation evident. 8.00 – 9.00 hr Gastrula Gastrulation converts the embryo into a two- layered structure, with an outer epiblast and inner hypoblast.