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Editor-in-Chief Published under auspices of Dan Mires The Society of Israeli Aquaculture and Marine Biotechnology (SIAMB), Editorial Board University of Hawaii at Manoa Library Sheenan Harpaz Agricultural Research Organization and Beit Dagan, Israel University of Hawaii Aquaculture Zvi Yaron Dept. of Zoology Program in association with Tel Aviv University AquacultureHub Tel Aviv, Israel http://www.aquaculturehub.org Angelo Colorni National Center for Mariculture, IOLR Eilat, Israel Rina Chakrabarti Aqua Research Lab Dept. of Zoology University of Delhi Ingrid Lupatsch Swansea University Singleton Park, Swansea, UK Jaap van Rijn The Hebrew University Faculty of Agriculture Israel Spencer Malecha Dept. of Human Nutrition, Food and Animal Sciences University of Hawaii Daniel Golani The Hebrew University of Jerusalem Jerusalem, Israel Emilio Tibaldi Udine University Udine, Italy ISSN 0792 - 156X Israeli Journal of Aquaculture - BAMIGDEH. Copy Editor Ellen Rosenberg PUBLISHER: Israeli Journal of Aquaculture - BAMIGDEH - Kibbutz Ein Hamifratz, Mobile Post 25210, ISRAEL Phone: + 972 52 3965809 http://siamb.org.il The Israeli Journal of Aquaculture – Bamidgeh 57(3), 2005, 191-196. 191 EFFECT OF SALINITY ON GESTATION PERIOD, FRY PRODUCTION, AND GROWTH PERFORMANCE OF THE SAILFIN MOLLY (POECILIA LATIPINNA LESUEUR) IN CAPTIVITY K.P. Kumaraguru vasagam*, S. Rajagopal, and T. Balasubramanian Center of Advanced Study in Marine Biology, Annamalai University, Parangipettai 608 502, Tamilnadu, India (Received 5.1.05, Accepted 2.2.05) Key words: FCR, fry yield, gestation period, Poecilia latipinna, salinity Abstract Breeding and growth trials were carried out with Poecilia latipinna in different salinities (0.5, 10, 15, 25, and 35‰) and effects on gestation period, fry production, and fry growth (75 days) were examined. Results showed that while P. latipinna successfully spawned in all salinities, there was a significant difference in fry production among treatments. The minimum gestation period was 28 days in all salinities except fresh water (0.5‰); the maximum fry production was obtained in 25‰. Fry growth was highest in 10‰ and significantly differed (p<0.05) from the rest of treat- ments in terms of weight gain, specific growth rate (SGR), and feed conversion ratio (FCR). Maximum SGR was 3.35% per day in 10‰ salinity. FCR ranged 4.28-5.67. The results suggest that the optimum salinities for breeding and rearing P. latipinna are around 25‰ and 10‰, respectively. Introduction Livebearing Poecilia latipinna (Lesueur), com- fish breeding as it is hardy and very easy to monly called sailfin molly, is a popular orna- breed with simple water holding facilities; no mental fish bred commercially in many coun- hi-tech accessories or excessive human tries throughout the world including tropical efforts are required (Ramachandran, 2002). India (Ghosh et al., 2003). This fish is highly Many researchers demonstrated the remark- recommended for beginners in ornamental able tolerance of poeciliid fishes in wide * Corresponding author. Tel.: +95-4144-243223/070; fax: +95-4144-253555; e-mail: [email protected] 192 Kumaraguru vasagam et al. ranges of temperature (Bennett and Beitinger, brooders (3.12–3.17 g) were separated from 1997) and salinity (Kristensen, 1969; Nordlie the common holding tanks and stocked into and Mirandi, 1996; Haney and Walsh, 2003). 500-l circular fiberglass tanks at the rate of Sailfin mollies tolerate a wide range of salinity one female per tank. Two males were select- from 0 to 120‰ (Kristensen, 1969). Nordlie et ed and introduced into the tanks containing al. (1992) reported the occurrence of wild poe- the females every 20 days. The males were ciliid fishes (guppies and mollies) in fresh left in the tanks three days and kept separate- water and brackish waters. However, most ly in the same salinity for the rest of the cycle. aquarium hobbyists and ornamental fish farm- Each salinity treatment had six replicates. The ers keep and breed sailfin mollies in fresh tanks contained plastic plants to offer hide- water (Ramachandran, 2002; Ghosh et al., outs for the free-swimming fry and were 2003). closed with net screens to prevent brooders Salinity is a major influencing factor on from jumping out. reproductive physiology in fishes (Ellis et al., The breeding trial was carried out for six 1997; Watanabe et al., 1998; Claireaux and months excluding the initial acclimatization Lagardere, 1999). Although several investiga- period. Health and fertility of the fish were tors reported salinity tolerance of poeciliid observed daily. For each spawning, the total fishes (Kristensen, 1969; Nordlie et al., 1992; number of fry (fry production), gestation peri- Arai et al., 1998), no scientific work on the od (number of days between two successive effect of salinity on breeding and growth per- spawnings), and weight of the newly released formance of P. latipinna has been done. The young were recorded. The newly released goal of the present study was to assess the young were regularly removed from the effect of salinity on breeding and growth per- brooder tanks and transferred to separate formance of P. latipinna in captive conditions. tanks. They were fed formulated feed in the form of paste 3-5 h after spawning. Materials and Methods Broodstock were weighed prior to stocking Fish and salinity acclimatization. Four hun- and after each spawning. Live fish were trans- dred 5-week-old P. latipinna were purchased ferred to a tarred vessel containing the same from a local ornamental fish farm, brought to habitat water and weighed on an electronic the laboratory in oxygenated bags, and accli- scale (Metler™) to the nearest 0.01 g. Several matized to laboratory conditions in fresh water fry from each spawning were sacrificed for (bore well). To avoid size and age differences, weighing. fry spawned on a single day were selected Growth trial. A separate growth trial (75 and stocked in a 4000-l concrete tank. After days) was conducted with young from the three days, five batches of 60 young fish were fourth spawning. The young (one week old) randomly restocked into five 1000-l circular were stocked in 100-l circular plastic troughs fiberglass tanks with fresh water. The fry were (at 25 young/trough) in the same salinity in gradually acclimatized to one of five salinities which they were spawned, with three repli- (0.5, 10, 15, 25, and 35‰) by increasing the cates per treatment. Experimental conditions salinity of the ambient water with sea water at and water quality parameters were similar to the rate of 2‰ per day until the final salinity those of the broodstock. Daily observations was reached. Fish kept in 0.5‰ salinity (fresh were made of survival and health. Samples of water) served as the control. Fish were raised fry were weighed fortnightly (as described to maturity and survival and behavior in the above) and weight increments were deter- respective salinities were observed. mined. At the conclusion of the growth trial, the Breeding trial. Fish were sexed according mean weight gain and survival of each salinity to the presence or absence of the male geni- treatment were determined. Analyzed parame- tal organ (‘gonopodium’, a modified anal fin). ters included: feed conversion ratio (FCR) = Fish lacking this organ were considered dry feed offered/weight gain and specific female (Dawes, 1991). At maturity, female growth rate (SGR) = [(lnWt – lnWi) x 100]/T, Kumaraguru vasagam et al. 193 where Wt = mean final weight, Wi = mean ini- Breeding performance. Fish released tial weight and T = total experimental days. young in all salinities (Table 1). The earliest Diet and feeding regime. Feed was formu- fry were released in the 15‰ salinity tanks lated to contain 451 g crude protein and 61 g after six days. During the second spawning, crude lipid per kg feed, with conventional feed the gestation period in all five batches was 28- ingredients as recommended by Kruger et al. 35 days. From the third spawning onwards, (2001). Broodstock and fry were fed ad libitum fish in all but the 0.5‰ salinity treatment in three rations per day (at 08:00, 13:00, and spawned once in 28 days. There were no sig- 18:00). Two hours after feeding, fecal matter nificant differences in gestation period among and unconsumed feed were siphoned from the the salt water treatments, but the difference tank bottom and discarded. In the growth trial, between brooders kept in fresh water (0.5‰) to calculate feed intake, uneaten feed was and those kept in salt water was significant. In manually sieved from fecal matter, washed the sixth spawning, fry production was highest with distilled water, dried in an oven (55°C), in the 25‰ treatment and lowest in the fresh- pooled for each replicate, and weighed. water treatment (Table 2). A few underdevel- Experimental conditions. The photoperiod oped young were obtained in the first spawn- was 12 h light:12 h dark. Continuous aeration ing in all salinities. There was a significant cor- was provided from an aquarium air compressor relation between the fry yield and weight gain through airstones. Water was exchanged at of the female brooders.