Early development and larval rearing of the exotic ornamental fish Carassius auratus
R. Linsha,G. Sreelekshmi,S. Amina, *L. Bindu
Post Graduate Department of Zoology,M.S.M.College,Kayamkulam,Alappuzha, Kerala, India – 690502.
* Corresponding authore-mail:
Abstract
Among the commercially important ornamental fishes traded in Kerala the exotic cyprinid Carassius auratus commonly known as Gold fish fetch a very high price in the international market. The present study provides the embryonic and larval rearing of this species. Carassiusauratus is an egg scatterer.The fertilized eggs are adhesive and spherical with an average diameter of 1.3 mm. Egg collectors made of polythene strips were provided for collecting the eggs. Hatching occurred in 38 h after fertilization, producing larvae with a mean size of 4.7mm. Mouth developed and prominent in 2 day old larvae. Yolk absorption was completed five days after hatching and the larvae attained a size of 6.3 mm by the 6th day. The larvae accepted exogenous particulate feed by fifth day onwards. The larvae achieved better growth (2.52 ± 0.71 cm) in 45 days. This technology can be utilized for the women entrepreneurs in their backyard hatcheries.
Keywords: Ornamental fish, Carassius auratus, embryonic development, tank rearing
Introduction
Ornamental fish culture is emerging as one of the most promising enterprises for providing economic security to rural population. India’s contribution to world ornamental fish trade is negligible. Gold fish,belongs to the familyCyprinidae, is the most popular freshwater fish species in the aquarium trade industry due to its elegance, reproductive capacity and adaptability to captivity with high economic value. It is an omnivorous fish, feeds on planktonic crustaceans, phytoplankton, insect larvae, fish eggs and fry, benthic vegetation, and detritus (Scott Crossman 1973; Courtenay Hensley 1980; Robison Buchanan 1988; Moyle 2002). This is very good fish for the community tank due to its compatibility and non aggressiveness.Larval rearing is the major bottleneck in its culture. Studies on larval development are useful in directing the husbandry efforts of fish farmer about the requirement of each larval stage(Wittenrich et al. 2007). The technique of larval rearing assumes significance in this context and will be helpful in the optimization of mass culture of this species. The proposed study aims to evaluate the early developmentand larval rearing aspects ofC.auratus), the prime candidate in the aquarium trade.
Materials and methods
Live and mature specimens of C.auratus were collected from the ornamental fish farm near Thalayazham, Kottayam district, Kerala. The seeds for the present study were produced by breeding these fishes in 1000 liters capacity silpolin tank filled with 650 liters of filtered rain water. As the eggs of C.auratus are adhesive in nature, 120 gaugepolythene strips (width 3.5 to 4.0 cm and length 45 to 50 cm) made into a bunchwas used as egg collector. The breeding set comprised one female weighing 35 g and three males weighing 28g, 26g and 22.5 g (since male is smaller than female, 3 males were used to obtain better result). Eggs collected from the polythene strips and their embryonic developments observed. Temperature, Dissolved Oxygen (DO) and pH of the experimental tankwere also monitored using standard methodology (APHA1998).Random samples of 5-10 eggs were collected and observed continuously under a trinocular microscope at 10x magnification. Egg sizes were measured to the nearest 0.01mm and the mean size was calculated. Embryonic and larval development stages were monitored. Dead eggs were pale yellow in colour and were removed carefully.Larval size was measured by taking the mean total length of 10 individuals on each day.
One week old larvae were shifted to cement tanks (1.02x 0.45 x0.29 m) and silpolin tank (1.02 x0.90 x0.38 m) after measuring initial length in mm and weight in mg. The rearing experiment (in duplicate) was conducted for 40 days for C.auratus (n=30), at the end of which the final length and weight of the juveniles were recorded. During this period the larvae were fed twice a day with powdered commercial pellets Meenoottu (Regional Agricultural Research Station, Kumarakom), with25% crude protein (fat 9%, mineral 7%, fibre 2%).
Result and Discussion
Fish farmers especially the women entrepreneurs are much less familiar with the breeding and rearing techniques of goldfish and non-availability of seeds similar to other cyprinids like koi carp (Meehan 2002). C.auratus was observed to be a broadcast spawner and the eggs were adhesive in nature. Spawning occurred, on the next day of broodfish transfer into the breeding tank, at a water temperature of 270 C (Table 1). A total of 276 eggs were observed with 73% fertilization and 60% hatching. The eggs were deposited singly and were highly adhesive throughout the incubation period. Due to the adhesive nature of the egg, considerable debris adhered to the capsule of the egg and the incubation period depends largely on the quality of water (Haniffa et al.2007).The embryonic developmental stages were observed and their characters were given in table 2.
Table 1. Water quality parameters in Carassius auratus breeding
Parameters / Breeding tank / Rearing tankpH / 7 / 7.5
Temperature 0C
(water)
(air) / 27
30 / 27
29
Salinity (ppt) / 0.155 / 0.218
DO (mg/L) / 3.4 / 3.6
Table 2. Embryonic development of Carassius auratus
Time (h:min.) / Description28 .30 / 50% of the yolk sac is covered by embryo, twitching movement occurs in a regular interval of time. Optic vesicles and notochord visible.
29.00 / Embryo covered 60% of the yolk sac, heart beat started and is 68/ min.
29 .15 / Heart beat is 72/min. 85% of yolk sac is covered by the embryo
29.30 / Heart beat is 74/min., movement of the embryo became faster
30 .00 / Size of egg enlarge, outer membrane disappear, tail movement increases
30.30 / Embryo covers 90% of yolk , heart beat is 96/min
32 .00 / Heart beat at 120/min , caudal region visible, vigorous tail lashing
32.30 / Heart beat at 128/min.
36.00 / Hatching started; whole eggs hatched out in 5-6 hours
In C.auratus, yolk occupied 80 % of the egg mass. As the development advances, the embryo appears more and more elongated and the tail appeared overlapping the head. In the present study the eggs hatched 38 hours after fertilization at 270C. By this time, the egg membrane becomes conspicuously thinner and tail emerged out first by its vigorous twitching movements. Mean size of the hatchling was4.7 mm (range:4.6 to 4.9 mm), retained the remnant yolk and is similar to that of other cyprinids (Haniffa et al. 2007; Udit et al. 2014). Hatchling appeared swimming in the water column with their attached spherical yolk sac on the ventral side.The hatchlings were slender and transparent with unpigmented eyes and without a distinct mouth. Morphological features of the larvae up to 7 days after hatching were provided in table 3.
Table 3. Larval development of Carassius auratus
Days after hatching / Size (mm) / Morphological DescriptionNewly hatched larva / 4.7 / dark eyes, transparent body, mouth not visible, auditory vesicles clear, pulsating tubular heart, heart rate 135/min., blood circulation upto the caudal fin clearly visible, chromatophores scattered in the anterior part of the body, head region attached to the yolk sac
2nd / 4.9 / Mouth visible, head appeared free from the yolk mass and yolk size reduced, dorsal and caudal fins developed
3rd / 5.2 / Size of larva increased, yolk reduced , mouth and operculum movements faster, pectoral fin movement visible
4th / 5.9 / Distinct mouth, jaw movement faster
5th / 6.1 / Yolk completely absorbed, started to feed external food
6th / 6.3 / Upper and lower jaw become well developed
7th / 6.5 / Fantail developed, operculum and pectoral fin became highly functional
As the hatchling development proceeds, the yolk sac gets fully reabsorbed by the third day. Pigmentation appeared on the dorsal portion of the head from the second day onwards. After the absorption of yolk the larvae began wandering in search of food. At this time they were fed with freshly prepared egg custard in the first 4 days and then with pellet feed. Growth of young ones in the first week after hatching was showed in Figure 1. Autonomous feeding and morphological changes characterized the larval stage. By this time the yolk was completely absorbed. In one week the hatchling reached 6.5 mm and transferred to culture tanks and fed on pellet feed.Fish meal is the major ingredient of this commercial pellet. Growth of cyprinids increase with increasing protein content upto 40% (Manivannan Saravanan 2012). They showed differential growth patterns, i.e., variation in sizes within the population. After 45 days of rearing their size ranged between 2 and 2.6 cm with a mean of 2.52 + 0.7076 (Table 4). Better growth and survival was obtained in the silpolin tank than that of the cement tank.
Figure 1. Post embryonic developmentof gold fish in the first week of hatching
The results of the present study could help the entrepreneurs in ornamental fish farming especially women in rural area to start backyard units for breeding goldfish, the most beautiful candidate in the ornamental fish industry.
Table 4. Growth performance of Carassius auratus
Parameters / Cement Tank / Silpolin TankT1 / T2 / T1 / T2
Initial length(cm) / 1.28 / 1.45 / 1.34 / 1.21
Initial weight(g) / 0.018 / 0.024 / 0.019 / 0.02
Stocking density / 30 / 30 / 30 / 30
Culture duration(days) / 40 / 40 / 40 / 40
Final length(cm) / 2.11 / 2.41 / 2.52 / 2.34
Final weight(g) / 0.183 / 0.217 / 0.298 / 0.286
Weight gain(g) / 0.165 / 0.192 / 0.279 / 0.267
Survival (%) / 48.97 / 42.62 / 51.63 / 66.66
Acknowledgements
The authors thank the Principal, M.S.M.College, Kayamkulam, Kerala, India for encouragement and providing facilities for the study. The authors are grateful to the University Grants Commission (UGC), India for funding the project (MRP(S)-1397/11-12/KLKE011/UGC-SWRO)
References
APHA 1998. Standard methods for examination of water and waste water. American Public Health Association, New York. 522pp.
Courtenay WRJr., Hensley DA.1980.Special problems associated with monitoring exotic species.In C.H. Hocutt and J.R. Stauffer, Jr. Biological monitoring of fish. Lexington Books, Lexington, Massachusett. pp 281-307.
Haniffa MA, Allen PSB,Arockiaraj AJ, Nagarajan M, Siby P. 2007. Breeding Behaviour and Embryonic Development of Koi Carp (Cyprinus carpio). Taiwania, 52(1): 93-99.
Manivannan S, Saravanan TS. 2012. Impact of formulated protein diets on growth of the Indian major carp, Labeo rohita (Hamilton). Fish.Aqua. Journ.,57: 1-6
Meehan WE. 2002. Fish culture in ponds and other inland waters. 1st ed. H. R. publishing house, Pilani, India. 285pp.
Moyle PB.2002.Inland fishes of California.Berkely University of California press.p 502.
Robinson HW,Buchanan TM. 1988. Fishes of Arkansas. University of Arkansas press.536pp.
Scott WB, Crossman EJ. 1973. Freshwater Fishes of Canada. Bulletin 184. Fisheries Research Board of Canada. 966pp.
UditUK, Reddy AK, Kumar P, Rather MA, DasR, Singh DK.2014.Induced breeding, embryonic and larval development of critically endangered fish Puntius sarana under captive condition. J.Animal Plant Sci., 24(1): 159-166
Wittenrich MW, Turingan RG, Creswell RL. 2007. Spawning, early development and first feeding in the gobiid fish Priolepis nocturna. Aquaculture,270:132-141.
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