The ontogeny of agonistic behavior and the onset of sexual maturation in the paradise fish, Macropodus opercularis (linnaeus)

Abstract

Fish 20-100 days of age were observed in brief conflicts with a stimulus fish of similar size and age. Four stages of behavior development were identified, based on quantitative changes in behavior which occurred with increasing age. Relatively little aggressive behavior occurs in the larval stage which includes fish up to about 40 days of age. Juveniles, age 40-70 days, approach, chase, and attack each other much more than do the larva. In the adolescent stage, 70-100 days of age, the incidence of species typical displays increases paralleling the onset of puberal changes in the testis and ovary. No sex differences in behavior were seen in fish up to 100 days of age. Among adult fish of unknown age males performed lateral threat displays more frequently than females as has been previously reported.Previous investigations in paradise fish (Macropodus opercularis) 2 indicate that males and females behave differently in social conflicts. For example, Southwick and Ward (1968) report that attacks occur sooner in encounters between females than in inter-male encounters, and that females may attack more intensively than males. Davis, Harris and Shelby (1974) found that in 5-10 rain encounters males performed threat displays more frequently than did females. In addition, mirror image stimuli were stronger positive reinforcers in males. The sexes show qualitatively similar threat displays, patterns of attack, and submissive postures (Forselius

Development of agonistic behaviour and vocalization in croaking gouramis

“…A similar order can be found in members of other families such as cichlids (Fraley & Fernald, 1982). This sequence followed that observed in individual encounters between two mature fish in all belontiids investigated (Davis & Kassel, 1975;Tooker & Miller, 1980;present study). Obviously, this is not a general characteristic in fishes.…”

“…This might either be explained by the absence of sounds in young, or by different experimental set-ups, and/or a true lack of appropriate equipment and recording conditions. The order of the appearance of behaviour patterns in an agonistic context in croaking gouramis is similar to those of other family members such as the paradise fish M. opercularis (Davis & Kassel, 1975) and the blue gourami Trichogaster trichopterus (Pallas, 1770) (Tooker & Miller, 1980). Approach, flight and chase appear in the second or third week after hatching, while threatening displays as lateral display occur later (fourth to sixth week).…”

“…Frontal display differs to some degree in various Belontiidae. Contrary to that noted in croaking gouramis, it consists mainly of abduction of opercula in the paradise fish, and is obviously absent in the blue gourami (Davis & Kassel, 1975;Tooker & Miller, 1980). Retreat behaviour occurs simultaneously with frontal display and mouth biting at the age of 10 weeks in croaking gouramis, but earlier (seventh week) in the blue gourami (Tooker & Miller, 1980).…”

“…described sound production in an aggressive context in the adult cichlids Cichlasoma nigrofasciatum (Gü nther) and Pterophyllum scalare (Cuvier & Valenciennes), but ontogenetic studies did not record sounds in juveniles (Bergmann, 1971; Williams, 1972). The ontogenetic study on the anabantoids Macropodus opercularis (L.) (Davis & Kassel, 1975) did not mention sounds either, although adult fish vocalize occasionally (Kratochvil, 1985). This might either be explained by the absence of sounds in young, or by different experimental set-ups, and/or a true lack of appropriate equipment and recording conditions.…”

“…The development of social and agonistic behaviour has been studied in representatives of several fish families such as salmonids (Dill, 1977;Cole & Noakes, 1980;Ryer & Olla, 1991), poeciliids (Dwyer & Beulig, 1991), cichlids (Ohm, 1964;Bergmann, 1971;Williams, 1972), centrarchids (Brown & Colgan, 1985) and belontiids (Davis & Kassel, 1975;Tooker & Miller, 1980;Miklosi et al, 1992). Agonistic behaviour could be observed first as early as a few days after birth in Poecilia (Dwyer & Beulig, 1991), but in most species it starts at the age of 3-4 weeks, for example in Salmo (Wright & Huntingford, 1993), Pterophyllum (Bergmann, 1971) and Trichogaster (Tooker & Miller, 1980).…”