Aspects of the reproductive biology of two archer fishes Toxotes chatareus, (Hamilton 1822) and Toxotes jaculatrix (Pallas 1767)

Abstract

Various aspects of the reproductive biology of two archer fishes Toxotes chatareus and Toxotes jaculatrix were studied to describe gonad development, spawning season, sex ratio, and fecundity. Spawning season was assessed using monthly changes in gonadosomatic index (GSI) and histological inspection of the gonads. Both species exhibit two modes of oocytes; a mode of small primary growth oocytes and a single mode that increases with size as oocytes sequester vitellogenin and undergo maturation, showing the synchronous oocyte development typical of total spawners. Based on GSI values and advanced stages of oocyte maturity, T. chatareus and T. jaculatrix, females appear to spawn from November to December. The average fecundity of female T. chatareus was 55 000±5538 eggs, and T. jaculatrix was 50 000± 3440 eggs; fecundity ranged from 20 000 to 150 000 eggs for both species, with relative fecundities of 600 to 1100 eggs/g body weight, and a mean value of 800±32 for T. chatareus; relative fecundity ranged from 500 to 1100 with a mean value of 700±23 for T. jaculatrix. Sex ratio, defined as the proportion of males to females, was 2.2 and 2.5 in T. chatareus and T. jaculatrix, respectively. The apparent abundance of males in samples could be due to females being positioned lower in the water column and therefore being sampled less frequently. Our results indicate that in both species, spawning occurs between the months of November and December during the monsoon season, which provides the mangrove coastal waters inhabited by these species with an abundance of food resources and additional floodplain nursery habitat for larvae and juveniles.

温度和喂食影响摩拉吧笛鲷体长体重关系和肥满度的研究

“…The fish were then deprived of food for two days and anesthetized with α-methyl quinoline (TransmoreR; Nika Trading, Puchong, Malaysia; 0.22 ml/L in 3 L of sea water as an aneasthetic medium for 10-15 min) prior to the initial measurement of total length (cm) and body weight (g). The total length was measured to the nearest 0.01 cm with a measuring board (Simon et al, 2010a) and weighed to the nearest 0.01 g (Simon et al, 2010b) using an electronic balance Model KD-300KC (Simon et al, 2012). After the starvation period, the fish were fed to satiation (Das et al, 2014b;Mazumder et al, 2015a) and offered two different diets, pellet or shrimp (four compartments for pellet and four compartments for shrimp), the leftovers after 2 min of feeding.…”

A spitting image: specializations in archerfish eyes for vision at the interface between air and water

“…Recently, archerfish have become a model for investigating learning (Timmermans & Vossen 2000;Schuster et al 2004Schuster et al , 2006, as well as neural coding and circuitry in the visual system (Segev et al 2007). Yet, surprisingly little is known about archerfish basic biology Simon et al , 2009) let alone their vision (Lü ling 1956(Lü ling , 1958Braekevelt 1985a,b;Plotkin et al 2008), which is central to foraging and predator evasion both above and below the water's surface. We report on two basic parameters of archerfish vision; visual pigments and spatial resolving power, which were found to be tuned to life at the interface between air and water with specializations for spitting at targets above the water's surface.…”

REPRODUCTIVE ASPECTS OF SCALLOPED PERCHLET, Ambassis nalua (HAMILTON, 1822) IN PABEAN BAY INDRAMAYU, WEST JAVA

“…Kondisi yang sama juga ditemukan beberapa ikan pesisir seperti pada ikan Micropogonias furnieri di Teluk Sepetiba, Rio de Jeneiro (Vicentini and Araujo, 2003), Parambassis ranga di perairan Haebaru, Okinawa (Ishikawa and Tachihara, 2011), akan tetapi berbeda dengan Ambassis nigripinnis yang memiliki nisbah kelamin dengan pola 1 : 1 sepanjang tahun (Milton and Arthington, 1985). Vazzoler (1996) menjelaskan bahwa jika dianalisis berdasarkan jumlah kelas panjang, dominasi ikan betina terjadi pada selang kelas yang lebih besar dan ikan jantan berada pada selang kelas yang kecil seperti pada ikan Toxotes chatareus dan Toxotes jaculatrix di perairan pesisir Johor (Simon et al, 2012) dan Plagioscion squamosissimus di estuari Amazon (Barbosa et al, 2012), hal ini dikarenakan taksa pertumbuhan ikan betina lebih tinggi dibandingkan ikan jantan. Perbedaan nisbah kelamin juga dipengaruhi oleh ketersediaan makanan dan laju pertumbuhan Vicentini and Araujo (2003); tingkat kematian antara ikan jantan dan ikan betina (Bedoui and Gharbi 2008).…”